Glossary

ABSOLUTE HUMIDITY

The mass of moisture (i.e. water vapour) present in one kilogram of an air/moisture mixture.  The measurement unit for absolute humidity is kg/kg.

ABSOLUTE PRESSURE

The pressure of a fluid measured above a perfect vacuum (which has zero absolute pressure).  If the pressure of the atmosphere is 101 kPa absolute, this is 101 kPa above absolute zero.  The pressure indicated on a pressure gauge can be converted to absolute pressure by adding atmospheric pressure to the gauge reading.

ABSOLUTE ZERO

The temperature at which all molecular motion ceases. This occurs at the zero point on the absolute temperature scale, which is at 0 Kelvin. This is equivalent to minus 273.16 degrees on the Celsius scale.

ABSORBENT

A substance that is capable of extracting into itself one or more of the constituents from another gas and/or liquid mixture. Usually, the absorbent undergoes a physical or chemical change during the extraction. An example is the chemical, amine, which can absorb hydrogen sulphide from raw natural gas.

ABSORBER

The area of the low side of an absorption system used for absorbing vapour refrigerant.

ABSORPTION

The process by which some of the atoms, molecules or ions of a gas or liquid mixture are brought into (i.e absorbed by) a different solid or liquid.  Absorption often involves a chemical reaction.

ABSORPTION REFRIGERATION

The process where exhaust steam and a pump is used in place of the refrigeration compressor.

ABSORPTION TOWER

A vertical, cylindrical pressure vessel in which two fluids contact each other and one fluid absorbs certain constituents from the other. An example is the contactor in a gas sweetening system, which uses amine to absorb hydrogen sulphide and carbon dioxide from raw natural gas.

ACCUMULATOR

A type of safety device, located between the evaporator and the compressor, used to reduce the liquid refrigerant carryover flow to the compressor suction.

ACETONE

A colourless, volatile, inflammable liquid (CH3COCH3).

ACETYLENE

A colourless gas (C2H2) prepared by the action of water with calcium carbide. Acetylene is used in gas welding and cutting.

ACID

A substance that, when dissolved in water, produces a solution containing hydrogen ions (H+). A substance capable of donating a proton (+) to another substance. The strength of an acid is determined by its pH value.

ACID (SULPHITE) PROCESS

A chemical pulping process that uses an acidic calcium sulphite solution plus heat to break the bonds in wood between the cellulose and the wood fibres.

ACID GAS

Any gas that contains a significant amount of constituents that may form acids when mixed with water. An example is the acid gas, consisting largely of hydrogen sulphide and carbon dioxide, created in the process of sweetening natural gas.

ACID PROCESS

A steel-making process that uses an acid type slag.

ACIDITY

In water: the excess of hydrogen ions (H+) over hydroxide ions (OH-) that occurs where the pH is less than 7.

ACTIVATED ALUMINA

A form of aluminium oxide that readily absorbs moisture and is commonly used as a drying agent. For example, wet instrument air may be passed through a bed of activated alumina pellets, where the alumina removes the moisture from the air.

ACTUAL AIR (FREE AIR) DELIVERED

The quantity of inlet air (i.e free air,  at the conditions of temperature and pressure existing at the inlet) delivered by an air compressor.  This quantity is expressed in cubic meter per minute.

ACUTE ANGLE

An angle that is greater than 0 degrees but less than 90 degrees.

ADJACENT ANGLES

Two angles that share a common vertex and a common line and do not overlap.

ADSORBENT

A solid substance with surface areas that are capable of extracting one or more constituents from a mixture of gases and/or liquids by the physical attraction of the extracted material onto the surface areas. No physical or chemical change of the adsorbent results.

ADSORPTION

The physical attraction and binding of atoms, molecules or ions of one substance onto the surface of another substance.

AFC

Alberta Fire Code.

AFTERCOOLER

A heat exchanger that removes the heat of compression from the air (or other gas) after it leaves the last stage of a compressor.

AGGLOMERATION

The coming together of small, scattered particles into larger, heavier particles, called floc, which are then able to settle easier and faster out of a liquid. Refer to *Floc*.

AIR CONDITIONING

The simultaneous control of the physical and the chemical conditions of the atmosphere within a structure. This is achieved by affecting some or all of the following air conditions: temperature, humidity, motion, distribution, pressure, dust, bacteria, odours, toxic gases, and ionization.

AIR DIFFUSER

A device, usually at the ceiling, used for the distribution of the conditioned air from the terminal of the air duct(s).

AIR GAP

In an electrical machine, the space between the rotor and stator across which magnetic lines of flux must travel through air.

AIR PREHEATER

A heat exchanger, located near the flue gas exit of a boiler, which transfers heat from the flue gas to the combustion air entering the boiler. This preheating of the air improves the combustion efficiency.

AIR-COOLED CONDENSER

A heat exchanger which uses a natural or forced flow of ambient air around the outside of a set of tubes to cool and condense a vapour contained inside the tubes.

AIR-TO-FUEL RATIO

The amount of combustion air, in kg, supplied to a boiler for each kg of fuel burned.  Expressed as a ratio it is "kg of air/kg of fuel".

ALIGNMENT

The position of one piece of equipment relative to another.  An example is the "alignment" of the shaft of motor with the shaft of the pump that the motor is driving.

ALKALI

A soluble salt, principally of sodium, potassium, magnesium, and calcium, that has the property to combine with acids to form neutral salts.

ALKALINE (SULFATE OR KRAFT) PROCESS

A chemical pulping process that uses an alkaline cooking liquor, caustic soda, plus heat to break the bonds in wood between the cellulose and the wood fibres.

ALKALINITY

The capacity of water to neutralize acids. This capacity is caused by the water's content of carbonate, bicarbonate, hydroxide, and occasionally borate, silicate and phosphate.

ALLOWABLE STRESS

The maximum internal stress that a structural metal may be subjected to under normal operating conditions.  This stress is determined by dividing the ultimate stress (i.e the stress at which the metal will break) by a factor of safety.

ALLOY

A metal that is produced by mixing certain metals with a base metal for the purpose of achieving improved qualities over the base metal. An example is stainless steel, which has more chromium in it than carbon steel.

ALTERNATING CURRENT

Electric current that reverses direction in a conductor with constant frequency.

ALTERNATION OF A CYCLE

That part of the sine wave cycle in which the emf or current value rises from zero to a maximum and reduces back to zero again in one direction. An alternation is one half of a cycle.

ALU

Arithmetic Logic Unit, a computer component where all arithmetic and logical operations are performed.

AMBIENT AIR

The air surrounding an object.

AMBIENT TEMPERATURE

Temperature of the surrounding air.

AMINE REGENRATION

The part of the gas sweetening process that separates the sour gas from the amine solution so the amine can be reused.

ANALOG

In computer terminology, analog means continuous over a range of values.

ANALOG COMPUTER

A computer in which numerical data are represented by continuously variable measurable physical properties, such as electrical signals.

ANGLE

The union of two lines with the same vertex.

ANGULAR MISALIGNMENT

A situation in which the center lines of the two shafts are at an angle to each other in either a horizontal or vertical position.

ANION

An ion that is negatively charged, i.e., Cl-.

ANTHRACITE

A coal with over 90% fixed carbon.

ANTI-FRICTION BEARINGS

Bearings composed of two pieces of metal separated by rolling elements.

APPLICATION PROGRAMS

A computer program designed for a specific task or use.

AQUASTAT

A hot water boiler fitting that controls the starting and stopping of the burner by sensing the temperature of the water.

ARC WELDING

A group of welding processes that produce the coalescence of metals by heating them with an arc with or without the application of pressure and with or without the use of filler metal.

ARGON

A colourless gas, chemically inactive used for shielding the weld from atmosphere in welding.

ARITHMETIC LOGIC UNIT

A computer component where all arithmetic and logical operations are performed.

ARMATURE

The conductors of a generator in which emf is induced or the conductors of a motor in which torque is produced.

ARMATURE REACTION

The effect caused by the interaction of the magnetic field of the current carrying conductors in the armature with the main magnetic field. The two magnetic fields combined cause a distortion in the overall magnetic field that results in a shift in the neutral plane in the direction of armature rotation.

ARTIFICIAL INTELLIGENCE

The ability of a machine to perform those activities that are normally thought to require intelligence; also the branch of computer science concerned with the development of machines having this ability.

ARTIFICIAL RESPIRATION

The manual technique of breathing for a non-breathing casualty. Also referred to as rescue breathing.

ASA

American Standards Association.

ASME

American Society of Mechanical Engineers.

ASME CODE

Codes developed by the American Society of Mechanical Engineers for use in design and construction in industry.

ASPIRATING PSYCHROMETER

A device consisting of two thermometers mounted side-by-side, one having a bare bulb and the other having a bulb covered with fabric. A fan is used to draw air over the thermometers.

ASTM

American Standard for Testing of Materials.

ATHEROSCLEROSIS

A cardiovascular condition in which there is an accumulation of cholesterol and fatty acids inside the arteries, which leads to a narrowing or hardening of the arteries.

ATMOSPHERIC PRESSURE

Air pressure at sea level. Taken as 101.3 kPa.

ATOM

The smallest part of an element that can exist and still retain the properties of the element; i.e. a nucleus and surrounding electrons.

ATOMIC NUMBER

A number that indicates both the number of the protons and number electrons in the atom.

ATOMIC SYMBOL

An abbreviated means of identifying an element. i.e. C is the chemical symbol for the element carbon.

ATOMIC WEIGHT (MASS)

The sum of the protons and neutrons in the atom.

AUSTENITE

A high temperature crystalline phase in steel in which the crystal structure is face centred cubic.

AUTOMATIC EXPANSION VALVE

An expansion valve actuated by changes in pressure in the evaporator to maintain a constant pressure in the evaporator.

AUTOMATIC FIRE DETECTION

Devices that automatically monitor for and sense the occurrence of a fire and, in some instances, will be used to extinguish the fire.

AUTOTRANSFORMER

A transformer that contains only one winding that serves as both the primary and the secondary winding.

AUXILIARY EQUIPMENT

All the equipment required, such as pumps, fans, fuel supply, and others, required for the efficient and safe operation of a system.

AWS

American Welding Society.

AXIAL

Refers to alignment with the axis of a machine. An axial force acting on a pump shaft would be acting along the shaft.

AXIAL FLOW COMPRESSOR

A compressor that uses rotor blades shaped like airfoils that give the air a high velocity and push it into subsequent stationary blade passages that convert the velocity energy into pressure. This process is repeated through several stages. The airflow movement is axial.

AXIAL FLOW PUMP

A type of vertical turbine pump that uses a propeller instead of an impeller. The water flow is axial.

BABBITT

Bearing metal of non-ferrous material, containing several tin-based alloys, mainly copper, antimony, tin and lead.

BACKFLOW PREVENTION DEVICE

A device that is installed to prevent the backwards flow of potentially contaminated water, gas, or other substance into any potable water supply or distribution piping.

BACKWASH

A flow through a vessel in the opposite direction of normal flow employed to clean the bed material.

BAFFLE

A wall or wall section located in the gas passage used to change the direction of the flue gas flow so maximum heat will be absorbed.

BALANCED DRAFT

The use of forced and induced draft fans to create a furnace draft at or just below atmospheric pressure.

BALANCING RESERVOIR

A holding basin in which variation in flow and composition of a liquid are averaged. Such basins are used to provide a flow of reasonably uniform volume and composition to a treatment unit.

BALL BEARINGS

Anti-friction bearings containing races and spherical rolling elements designed to support and locate rotating shafts or parts in machines.

BALLAST

An electromagnetic device used with a gas discharge lamp to control starting and operating conditions.

BALLAST GAS

The non-flammable portion of gas, such as carbon dioxide.

BARKING DRUM

A vessel used to remove the bark from incoming logs in a pulp mill.

BARRING GEAR

Refer to Turning Gear.

BASE

A substance, that when dissolved in water, produces hydroxide (OH-) ions.

BASE LOADING

When an electric generating system consists of several electric generating units and where the first unit is fully loaded at a constant load, and the second generating unit may control the load demand.

BASEBOARD HEATERS

Tubular hot water or steam heating elements that have aluminium fins mounted on exterior walls near the floor and covered with vented sheet metal casings.

BASIC PROCESS

Process of making steel using a basic type slag.

BATCH PROCESS

A treatment operation in which a vessel or reactor is filled, the process is treated, and the vessel is emptied. It may then be refilled and the process repeated.

BELLOWS

A corrugated metal tube that is designed to expand or contract when pressure is applied.

BELLOWS SEAL

A metal bellows used in place of packing for valves and compressor shafts.

BIMETAL ELEMENT

A strip or coil that consists of two different metals having different thermal expansion rates that are bonded together.

BIMETAL THERMOMETER

A temperature-sensing device employing a bimetal element.

BIOSPHERE

The life-supporting surroundings and its immediate atmosphere where interactions occur between the organisms and the environment.

BIT

In computer science, a single character of a language having just two characters, as either of the binary digits 0 or 1; a unit of information equivalent to the choice of either of two equally likely alternatives; a unit of information storage capacity, as of memory.

BITUMINOUS

A coal with approximately 60% fixed carbon.

BLADE FOULING

Contaminants, present in the air or the fuel, are deposited on the blades of a compressor or turbine.

BLAST FURNACE GAS

The waste product from furnaces used to smelt iron ores.

BLINDING

The clogging of filtering medium of a micro screen or a vacuum filter when the holes or spaces in the media become sealed off due to grease or the material being filtered. Also, insertion of blind flanges into a pipeline for isolation purposes.

BLOCK VALVES

Valves used simultaneously to isolate a specific section of a system for maintenance or inspection of that section.

BLOCK(S)

A group of pulleys on the same shaft. A continuous rope is wound over two such blocks to form a machine that will provide a mechanical advantage.

BLOW TANK

In a pulping process, a vessel that receives the solution of chips and chemicals before the solution is washed; where the steam from the digester is removed to atmosphere. The chips and chemical are blown into the vessel causing the break-up of the chips.

BLOW-OFF VALVES

Valves that are opened to remove sludge and impurities from, or drain, a boiler or vessel.

BOILER

A pressure vessel in which water is heated to produce steam.

BOILER AND PRESSURE VESSEL CODE

An ASME code, The Boiler and Pressure Vessel Code establishes rules of safety governing the design, fabrication, and inspection of boilers and pressure vessels, and nuclear power plant components during construction.

BOILER BLOWDOWN

The process of releasing a portion of the water continuously or intermittently from a boiler to remove impurities in order to maintain predetermined concentrations.

BOILER CAPACITY

The mass, in kilograms, of steam per hour that a boiler is capable of producing.

BOILER DRUM

A pressure vessel part of a boiler that consists of a shell and heads.

BOILING POINT

The temperature at which a phase change occurs between liquid and vapour.

BOND

A strong force of attraction that holds atoms together in a compound or crystal.

BOUNDARY LUBRICATION

Where a very thin film of lubricant separates the rubbing surfaces.

BRANCH

In electricity, one of the paths of a parallel circuit along which current may travel.

BRAYTON CYCLE

An ideal cycle in which compression and expansion take place at constant entropy, an ideal gas turbine.

BRINE

A concentrated solution of a salt (NaCl) and water used in the regeneration of sodium zeolite softeners.

BRINE COOLER

Evaporator for cooling brine in an indirect cooling system.

BUFFER

A solution or liquid whose chemical makeup neutralizes acids or base without great change in pH.

BUFFER ACTION

The action of certain ions in solution in opposing a change in hydrogen ion concentration.

BUFFER CAPACITY

A measure of the capacity of a solution or liquid to neutralize acids or bases. This is a measure of the capacity of water or wastewater for offering a resistance to changes in pH.

BUFFER SOLUTION

A solution containing two or more substances that, in combination, resist any marked change in pH following addition of moderate amounts of either strong acid or base.

BULK SHIPMENT

In WHMIS, a shipment of a controlled product that is contained without intermediate containment or intermediate packaging.

BURNERS

Devices used to mix fuel and air for combustion.

BYTE

A sequence of adjacent bits operated on as a unit by a computer; the amount of computer memory needed to store one character of a specified size, usually 8 bits for a microcomputer and 16 bits for a larger computer.

CALORIE

The heat required to raise the temperature of 1 gram of water 1 degree Celsius.

CALORIMETER

A device used to measure heat quantities.

CANADIAN REGISTRATION NUMBER (CRN)

A registration number that is allotted to pressure vessel designs by the regulatory agency of the province where the design is registered.

CANDU REACTOR

The Canadian version of the nuclear reactor; the main difference from other reactors is the use of heavy water as a moderator and heat transfer medium.

CANNULAR COMBUSTION CHAMBER

A type of combustion chamber composed of liners located circumferentially within an annular combustion chamber case.

CAPACITANCE

The property of an electric circuit to store energy by means of an electrostatic field and release it at a later time.

CAPACITOR

A device that has the ability to store electrical charge and is made of two conductive plates separated by a dielectric (insulator).

CAPILLARY TUBE

A tube of small internal diameter used as a liquid refrigerant flow control and pressure reducer between high and low pressure sides. Also used to transmit pressure from the sensitive bulb of some temperature controls to the operating element.

CAPLLIARITY

The force by which the liquid, in contact with a solid, is distributed between closely fitted surfaces of joints to be brazed or soldered.

CARBON

A non-metallic element, symbol C, atomic number 6, atomic mass 12.01. It is a main constituent of most fuels and is added to iron in the production of steel.

CARBON DIOXIDE EXTINGUISHERS

A fire fighting device consisting of a cylindrical vessel containing carbon dioxide under high pressure with a release trigger and discharge horn.

CARDIO PULMONARY RESUSCITATION (CPR)

Rescue breathing and chest compressions on a casualty in cardiac arrest.

CARRYOVER

The entrainment of water droplets in the steam leaving the boiler drum.

CASCADE EVAPORATOR

A heater that uses sensible heat from the flue gas of a recovery boiler to increase the black liquor concentration to 60%.

CAST IRON

Iron containing between 2 and 4 % carbon. Noted for its rigidity and brittleness.

CATALYST

Substances that will speed up or slow down a chemical reaction.

CATION

A positively charged ion, i.e. hydrogen (H+).

CAUSTIC EMBRITTLEMENT

The intercrystalline cracking of steel caused by the presence of free NaOH, stress, boiler water leakage, and concentration of NaOH.

CAUSTICIZER

In a pulp mill, a process used to convert the green liquor into white liquor by adding lime.

CAVITATION

Vaporising of liquid that occurs at any point when the liquid’s pressure falls below its vapour pressure, or boiling point.

CD-ROM

A compact disk that functions as a read-only memory.

CELLULOSE

Wood fibres used in the production of pulp.

CELSIUS

A temperature scale with gradients between the freezing and boiling points of water are divided into 100 equal parts.

CENTRAL PROCESSING UNIT (CPU)

The part of a computer that interprets and executes instructions.

CENTRALIZED AIR CONDITIONING

When all the necessary conditioning of the air occurs in one location for distribution to a wide area.

CENTRE OF GRAVITY

The point through which it is assumed that the force of gravity acts on a body.

CENTRIFUGAL COMPRESSOR

A compressor that compresses gases by centrifugal force.

CENTRIFUGAL FORCE

An apparent force that acts outward on a body moving about a center.

CENTRIFUGAL PUMP

A pump consisting of an impeller fixed on a rotating shaft and enclosed in a casing, having an inlet and a discharge connection. The rotating impeller creates pressure in the liquid by the velocity derived from centrifugal force.

CEO

Chief Executive Officer of a company.

CHARGING VALVE

Service valve used to charge or add refrigerant to the system, or add oil to the compressor crankcase.

CHECK VALVE

A valve that allows flow to occur in one direction only and will close automatically if a reversal of flow occurs.

CHEMICAL CHANGE

A change created when one or more new substances are produced with properties different from the original substance(s).

CHEMICAL ENERGY

Potential energy stored in elements or compounds and released through chemical reactions.

CHEMICAL FORMULA

Chemical symbols that represent a certain compound i.e. H2O = water.

CHEMICAL HAZARDS REGULATION

Developed under the authority of the Occupational Health and Safety Act, which establishes the fundamental principles of Alberta's occupational health and safety law.

CHEMICAL PROCESS

The process that uses chemicals to produce pulp from wood.

CHEMICAL REACTION

Any change that comes about through the chemical action of substances on each other, i.e. rusting and combustion are both chemical reactions involving the oxidation of a substance.

CHEMICAL SYMBOL

Refer to Atomic Symbol.

CHIPPER

A machine designed to reduce logs to small chips of wood to supply the digester in a pulp mill.

CIRCUIT BREAKER

A device designed to open a circuit and stop the flow of current when the current or voltage in the circuit exceeds a pre-set value.

CLARIFICATION

The process used to reduce the amount of suspended solids in water.

CLARIFIER

A settling tank used to remove sediment from water through sedimentation, coagulation or flocculation.

CLASS A FIRE

A fire fueled by solids, i.e. wood, paper, rags.

CLASS B FIRE

A fire fueled by flammable liquids, i.e. gasoline, oil, paint thinner.

CLASS C FIRE

A fire fueled by a live electrical current.

CLASS D FIRE

A fire fueled by a combustible metal, i.e. magnesium, potassium, sodium.

CLEARANCE PROCEDURE

A safety measure employed to ensure personnel are protected from hazards associated with dangerous equipment or areas.

CLOSED CYCLE

The gas turbine arrangement in which the working vapour exhaust is directed back again to the compressor without coming in contact with the atmosphere.

CLOSED LOOP

A control system that continually monitors the process, receives feedback of process changes, and then outputs corrections to a final control element to maintain a set point value.

CLOSED-TYPE EXPANSION TANK

A closed pressure vessel associated with a hot water heating system that absorbs the variations in water volume caused by changes in water temperature.

COAGULANT

A chemical that causes suspended matter to join together into larger particles. This makes it easier to remove the suspended matter from the liquid by settling, skimming, draining or filtering.

COAGULATION

The use of chemicals that cause suspended matter to join together into larger particles. This makes it easier to remove the suspended matter from the liquid by settling, skimming, draining or filtering.

COAL

A common boiler fuel comprised of hydrogen, oxygen, sulphur, nitrogen, moisture, and ash.

COEFFICIENT OF LINEAR EXPANSION

The change in length experienced by a solid of unit length per degree change in temperature.

COEFFICIENT OF PERFORMANCE

Ratio of the refrigeration produced to the work supplied.

COGENERATION

A term used to describe the combination of different thermodynamic cycles for the purpose of increasing all-over cycle efficiency.

COKE

A high quality coal used as a fuel and source of carbon in the refining of metal.

COMBINED CYCLE

Where heat from the exhaust gases of a gas turbine is used to generate steam to drive a steam turbine.

COMBUSTIBLE LIQUID

A product, material or substance that falls into Division 3 if it has a flashpoint of 37.8°C or more but less than 93.3°C.

COMBUSTION

A rapid chemical reaction in which oxygen combines with a fuel and releases heat and/or light.

COMBUSTION CHAMBER

The part of the boiler or furnace where fuel is mixed with air and combustion occurs.

COMBUSTION GAS PASS

Refers to the passage of combustion gases over or past the heating surfaces of a boiler.

COMBUSTION GASES

The hot gaseous products of combustion; may also be called flue gases.

COMFORT AIR CONDITIONING

The process of preparing the air for temperature, humidity, cleanliness and distribution to meet human comfort levels.

COMFORT COOLING

The use of a refrigeration system to provide comfort to human occupants, rather than refrigeration used for freezing, storage, etc.

COMFORT ZONE

A range of temperatures at which more than 50% of the occupants in that specified area feel comfortable.

COMMON FRACTION

Fraction expressed by two numbers separated by a line, i.e. 4/5, 1/12, 2/1.

COMMUNICATION

Transmitting knowledge and information back and forth between people.

COMMUTATOR

A device that converts the alternating current sine wave produced in all generator armatures into direct current at the dc generator terminals.

COMPLETE COMBUSTION

Where all of the combustible matter present in the fuel is oxidized and no combustible matter remains unburned.

COMPOUND

A pure substance made up of two or more elements combined in definite proportion.

COMPOUND GENERATOR

A generator in which the field contains two sets of windings; one connected in series and the other in parallel (shunt) with the armature.

COMPRESSION RATIO

The ratio of the volume at the beginning of a compression stroke to the volume at the end.

COMPRESSION STAGES

A term used to denote increase of pressure on a fluid by the use of mechanical energy in several steps or stages.

COMPRESSIVE FORCES

Forces that are acting toward each other and will tend to press together or compact the body.

COMPRESSOR

A machine designed for compressing air or vapour from a lower intake pressure to a higher discharge pressure.

COMPRESSOR SURGING

Instability of airflow in an axial or centrifugal compressor caused by conditions of low flow and high pressure.

COMPUTER PROGRAM

A series of instructions that a computer can interpret and execute; programs are also called software to distinguish them from hardware, the physical equipment used in data processing.

CONCENTRIC REDUCER

A device used to connect a large pipe to a smaller pipe such that the centre lines of both pipes are aligned.

CONDENSATE

Liquid formed from a vapour due to lowering of the temperature or increasing the surface pressure.

CONDENSATION

A process when a vapour forms a liquid after the withdrawal of latent heat.

CONDENSE

A process by which a vapour changes to a liquid.

CONDENSER

A heat exchanger that causes a vapour to change to a liquid by removing the latent heat.

CONDENSING TURBINE

A turbine in which the steam leaving passes into a condenser operating at a pressure below atmospheric.

CONDUCTION

Heat transfer that occurs via particle contact.

CONDUCTIVITY

A measure of the dissolved solids content of boiler water.

CONFINED SPACES

Areas that have limited entrance or exit opportunities.

CONSIGNEE

The person who is intended to receive the shipment.

CONSIGNOR

The person who provides a shipment of goods for transport.

CONTINUITY

Completeness. A circuit with continuity is a closed circuit.

CONTINUOUS PILOT

A manually ignited pilot that will burn continuously.

CONTROLLED PRODUCTS

Hazardous products that meet certain pre-determined criteria under WHMIS guidelines.

CONVECTION

Heat transfer via the movement of heated particles. I.e. circulation of water in a boiler.

CONVENTIONAL CURRENT DIRECTION

The convention that current flows from an area of positive charge to one of negative charge. In reality the electrons, and hence the current, travel from an area of negative charge to one of positive charge.

CONVERTER

A shell and tube heat exchanger where water flowing through tubes is heated by steam within the shell.

CORE

In electrical equipment, a material designed to conduct magnetic flux easily but offer high resistance to current. In a nuclear reactor, the area in which nuclear fission takes place and heat is produced.

CORROSION

The destruction of a metal by chemical or electrochemical reaction with its environment.

COULOMB

The unit of electrical charge; equivalent to the charge of 6.28 x 1023 electrons.

COUNTER EMF (CEMF)

An emf induced in a conductor by a change in current flow in the conductor. The cemf induced is in the direction opposite to the emf that caused the current flow.

COUNTER FLOW HEAT EXCHANGER

When the fluid to be cooled flows opposite to the direction of the coolant, the coldest condition of the fluid meeting the coldest condition of the coolant.

COUPLING

A device that connects and transmits power between two shafts.

CPR

Refer to Cardio Pulmonary Resuscitation.

CPU

Refer to Central Processing Unit.

CRITICAL PRESSURE

The pressure at which the specific volume of the liquid is equal to the specific volume of its vapour.

CRITICAL TEMPERATURE

The temperature above which it is impossible to liquefy a vapour regardless of how much pressure is applied.

CRN

Refer to Canadian Registration Number.

CSA

Canadian Standards Association.

CSA B-51 CODE

Canadian Standards Association Code for the Construction and Inspection of Boilers and Pressure Vessels. Its purpose is to provide for the safe design, construction, installation, operation, inspection, testing and repair of boilers, pressure vessels, and related equipment; and second, to promote uniform requirements among the Canadian jurisdictions.

CURRENT

The flow of electric charge through a conductor as a result of the movement of electrons. The symbol is I and unit is the ampere.

CUTTING TORCH (OXYFUEL)

A device used for directing and controlling a preheating flame and a supply of oxygen for cutting metal.

CYCLE

A complete sine wave form consisting of two alternations; first in one direction then in the other.

CYCLONE FURNACE

A type of furnace developed to burn lower grade coals, it is water cooled and insulated to maintain a high furnace temperature. Crushed coal enters with the primary air in the furnace tangentially, while the secondary air is supplied to the furnace chamber.

CYCLONE SEPARATOR

Separates entrained particles from the fluid steam by means of centrifugal force caused by changing direction.

DAMPER

A device used to control the flow of air or gases.

DANGEROUSLY REACTIVE MATERIAL

A product, material or substance that meets any one of three criteria: 1) undergoes vigorous polymerization, decomposition or condensation, 2) becomes self-reactive under conditions of shock, or increase in pressure or temperature, 3) reacts vigorously with water to release a highly toxic gas.

DATABASE

A collection of data arranged for ease and speed of search and retrieval.

DEAERATOR

A component used for removing dissolved oxygen or other noncondensables in boiler feed water.

DEBARKING

The process of removing the bark from the logs to facilitate further processing.

DEHUMIDIFIER

A device that removes moisture from the air.

DEHYDRATION

The removal of moisture from air, stored goods, or refrigerant.

DEMINERALIZATION

Removal of all ionisable salts using an ion exchange system

DENOMINATOR

The number below the line in a common fraction. If one is divided by five (1/5), then 5 is the denominator.

DESICCANT

Any absorbent or adsorbent, liquid or solid, that will remove water or water vapour from a material. In a refrigeration circuit, the desiccant should be insoluble in the refrigerant.

DEW POINT

The temperature at which the water vapour in the air is saturated; the temperature at which water vapour begins to condense out of the air.

DIAPHRAGM

A thin flexible plate held in place in a capsule in such a way that when pressure is applied to one side, the plate will bulge outward.

DIAPHRAGM PUMP

A pump in which a flexible diaphragm, generally of rubber or equally flexible material, is the operating part. When the diaphragm is raised suction is exerted, and when it is depress, the liquid is forced through a discharge valve.

DIFFUSER

An increasing cross-sectional area that is designed to convert high-speed fluid flow into low-speed flow at an increased pressure.

DIGESTER

A vessel used to cook the wood and chemicals to break down the lignin that binds the cellulose fibres together.

DIGITAL

In computer terminology, discrete, not continuous, as in analog.

DIGITAL COMPUTER

A computer that performs calculations and logical operations with quantities represented as digits, usually in the binary number system.

DIRECT CONNECTED

The driver and driven machines (e.g. Motor and compressor) are positively connected in line to operate at the same speed.

DIRECT CURRENT

Current that flows in one direction only in a circuit.

DIRECT EXPANSION COILS

Coils using the direct method of refrigeration.

DIRECT REFRIGERATION SYSTEM

A system in which the evaporator is either in direct contact with the material space to be refrigerated or located in the air circulating passages leading to the material space

DISPLACEMENT

Volume swept by piston per stroke.

DISSOLVING TANK

A vessel used to dissolve the smelt from the recovery boiler into a tank of water to produce green liquor.

DISTILLATION

A process where a liquid is vaporized to help separate the volatile portions.

DIVIDEND

A number to be broken down into smaller units by the divisor, i.e. *12* (dividend) / 4 = 3.

DIVISOR

The number by which the dividend is to be broken down, i.e. *12 / 4* (divisor) = 3.

DOMAIN

A group of atoms whose magnetic polarities agree and produce an overall magnetic field. A domain consists of 1014 to 1015 atoms; there are approximately 10 million domains per cubic centimeter.

DOS

Disk Operating System, an operating system that resides on a disk.

DOUBLE ACTING COMPRESSOR

A machine in which compression takes place on both strokes per revolution in each compressing element.

DOUBLE DIRECT SYSTEM

A system that uses flow of refrigerant from a secondary circuit to cool or condense the refrigerant of a primary circuit in an inter-cooler.

DOWN FEED SYSTEMS

A system where the incoming domestic water supply main provides suction to a booster pump that pumps water to a storage tank located at the top of the building. Water flows downward from the tank into the domestic water system.

DRAFT FANS

Mechanically driven fans used to either blow air into the furnace through the windbox or to draw the combustion gases from the boiler and expel them out the stack.

DRIFT ELIMINATORS

An arrangement of barriers within the cooling tower that removes condensate (water) from the air before the air exits to the atmosphere.

DRIP CONNECTION

The vertical length of pipe connecting the bottom of the steam supply main to the return piping.

DROP-FEED LUBRICATION

A system that feeds the lubricant in drops to the area required.

DRUM INTERNALS

Fittings located inside the boiler drum used to separate water and steam, distribute feed water and chemicals, and provide for removal of impurities.

DRY AIR

Air containing no water vapour.

DRY CHEMICAL EXTINGUISHERS

An extinguisher where the extinguishing agent is a dry powder and the propelling gas is either in the container in the upper chamber or on the side with a separate pressurized cartridge or canister.

DRY POWDER EXTINGUISHERS

These types of extinguishers are used only on metal, or class D, fires.

DRY RETURN

The portion of the return piping above the water line of the boiler.

DRY STEAM

Steam that does not contain water.

DRY TYPE EVAPORATOR

An evaporator of the continuous tube type where liquid refrigerant from a pressure-reducing device is fed into one end and the compressor suction line at the outlet removes the dry refrigerant vapour.

DRY-BULB TEMPERATURE

The temperature of a gas or mixture of gases indicated by an accurate thermometer when there is no heat flow to or from the thermometer bulb.

DRYER

A device used to remove moisture from a vapour.

DRYNESS FRACTION

The ratio of latent heat added in a mass of steam to the latent heat it could contain.

DUAL DRIVE

A pump or compressor having a turbine on one end and an electric motor on the other end.

DUAL SHAFT GAS TURBINE

A gas turbine connected to one shaft driving a compressor that directs discharged gas to a second turbine, connected to a separate shaft, to drive a load such as a generator.

DUCT HEATERS

In-duct heating elements that heat the air in warm air heating and ventilating systems.

DUCTILITY

A mechanical property that enables the metal to be drawn or lengthened without fracture.

DYNAMIC PUMP

A pump that increases the pressure of a liquid continuously by increasing its velocity energy and then changing it to pressure energy.

ECCENTRIC REDUCER

A fitting used to connect a large pipe to a smaller pipe so that one edge of both pipes is aligned.

ECONOMIZER

A heat recovery device used in a boiler to transfer heat in the combustion gases to feed water.

EDDY CURRENT

Currents caused by changing magnetic fields produced in armature and field cores of electrical machines that tend to interfere with the production of emf in the armature windings.

EFFICIENCY

The ratio of a machine’s energy output to energy input. It may be expressed as a decimal or a percent. Efficiency equals the work output divided by the work input or the actual mechanical advantage (AMA) divided by the ideal mechanical advantage (IMA).

EFFLORESCENCE

The powder or crust formed on a substance when moisture is evaporated from it.

EFFLUENT

The waste product of a process that is discharged to sewer or for further treatment.

ELASTIC LIMIT

The point on a stress-strain diagram where the curve starts to deviate from a straight line and after which the material will not return to its original shape.

ELASTICITY

The property that allows a material to deform under a load and return to its original shape after the load is removed.

ELECTRIC BOILERS

Boilers in which heat is produced by electricity rather than fuel oil or gas. Heat is produced either between two electrodes or by resistance to the flow of electricity through a coiled conductor.

ELECTRIC FURNACES

Furnaces in which the air is heated by passing directly over the electric heating elements. Electric energy is converted to heat using open wire resistance heating elements.

ELECTRIC INFRARED HEATER

Electric heaters consisting of long, slender tubes, similar in appearance to fluorescent lamp fixtures. The tubes fit into fixtures, which can be hung from the ceiling or wall, or mounted flush with the ceiling. A reflector is mounted behind each tube directs the radiant heat into the space to be heated.

ELECTRODE

A conductor that emits or collects electrons in a cell.

ELECTROLYSIS

The production of a chemical reaction by passing an electric current through an electrolyte.

ELECTROLYTE

A liquid or paste that conducts electricity as a result of the presence of positive or negative ions.

ELECTROMAGNET

A temporary magnet made of a ferromagnetic core wound with insulated wire through which is passed an electric current. The current flow through the windings causes a magnetic field to build that will attract magnetic material.

ELECTROMAGNETIC INDUCTION

The production of electromotive force (emf) in a conductor through relative motion of a conductor and a magnetic field, or by the change in the strength of magnetic flux around the conductor.

ELECTROMOTIVE FORCE (EMF)

The potential difference, expressed in volts, that is generated by a source of electric current.

ELECTRON

A small subatomic particle that contains a negative electric charge and is of negligible mass.

ELEMENT

A pure substance that cannot be broken down into simpler substances by chemical means.

EMF

Refer to Electromotive Force.

EMULSION

Where one liquid is trapped in another liquid, i.e. water and oil.

END PLAY

The amount of radial movement of a shaft.

END POINT

The point that a colour change occurs during titration, i.e. water testing - blue changes to clear.

END SUCTION CENTRIFUGAL PUMP

The most common style of centrifugal pump, either frame-mounted or close-coupled, where the centre of the suction line is centred on the impeller eye.

ENERGY

The ability to do work. Energy has the same units as work (Joules) and is convertible to many different forms such as heat, mechanical, chemical, nuclear.

ENTHALPY

Heat that is comprised of the internal energy plus the work done.

EQUILATERAL TRIANGLE

A triangle with three equal sides and three equal angles.

EQUIVALENT RESISTANCE

A theoretical resistance that is equivalent to two or more resistances in parallel.

ERROR

The difference in the amount between a measured or actual value of a variable and the desired or set point value

ETHYLENE GLYCOL

A substance injected in the gas steam to prevent the freezing of the condensed liquid to prevent the formation of hydrates.

EVAPORATION

The process of changing a liquid to a vapour state.

EVAPORATION LOSSES

The water losses from a cooling tower system to the air due to evaporation. Usually expressed in %.

EVAPORATIVE CONDENSER

A condenser cooled by the evaporation of water sprayed upon it.

EXCESS AIR

Air in addition to the amount of theoretical air needed for complete combustion.

EXCITATION

The production of magnetic flux by supplying electric current to the field poles of a generator to create a variable magnetic field.

EXCITER

A generator used to supply the field currents of a larger dc generator or alternator.

EXHAUSTION

The points in a process when the mediums used to perform purification are no longer able to perform their function.

EXOTHERMIC REACTION

A chemical reaction that will generate heat to produce a higher temperature.

EXPANSION JOINT

A device in piping designed to allow relative movement between two lengths of pipe.

EXPANSION VALVE

A device that controls the flow of refrigerant to the evaporator.

EXPLOSION

Uncontrolled rapid combustion.

EXPLOSIVES ACT

A federal law that regulates any substance that is made, manufactured or used to produce an explosion or detonation or a pyrotechnic effect and includes gunpowder, propellant powders, blasting agents, dynamite, detonating cord, lead azide, detonators, ammunition, rockets, fireworks, safety flares or other signals.

FACTOR

Two numbers multiplied together resulting in a product, i.e. 2 x 3 = 6 (2 and 3 are factors).

FACTOR OF SAFETY

The ratio of ultimate strength to allowable stress. It is used to ensure that a structural member is not subjected to excessive loads that would cause it to fail or not be able to perform the job it was designed for.

FAHRENHEIT

A temperature scale with graduations divided into 212 equal parts (Imperial/English system).

FAIL SAFE

Any device that either shuts down or prevents the start of a machine or system when there is a drop or loss of pressure, flow or level, etc.

FAN

A machine that causes energy to be added to air or other vapours to increase its pressure or velocity.

FAN

A machine that causes energy to be added to air or other vapours to increase its pressure or velocity.

FAUCET

Valves installed at the outlet connections of fixtures such as sinks, that are used to control the flow of water.

FBC

Fluidized Bed Combustion.

FEEDBACK

The part of a closed loop system which provides the controller with information about the controlled variable for comparison to its desired value.

FEEDWATER

Treated water that is supplied to the boiler to replace the boiler water that has been converted to steam and has been removed from the boiler.

FERROMAGNETIC MATERIAL

Material that contains magnetic domains that are relatively easily aligned to produce magnets. Ferromagnetic materials are iron, steel, cobalt, and alnico.

FERROUS METAL

A metal, the major component of which is iron.

FILTER

A device installed in a liquid or gas flow used to remove particulate matter.

FINAL CONTROL ELEMENT

The device that directly changes the value of the manipulated variable.

FIRE TUBE

Refers to the tubes of fire tube boilers through which combustion gases flow.

FIRE-TUBE BOILER

A boiler consisting of drum containing tubes through which hot combustion gases pass.

FIRST AID

Immediate care given to a casualty at the scene of an accident prior to obtaining advanced medical support.

FITTINGS

Devices fitted directly to a boiler or other piece of equipment that are used for safe and efficient operation.

FIXED OILS

Lubricants of animal or plant origin.

FLAME-OUT

A condition that occurs when the burner has lost its flame; also referred to as flame failure.

FLAMMABLE AEROSOLS

Any product, material or substance is included in Division 5 if it is packaged in an aerosol container and, when tested in accordance with the method set out in Schedule VI of the Controlled Products Regulations, produces a flame projection or a flashback.

FLAMMABLE GASES

A product, material or substance falls into this division if it is a Compressed Gas (Class A) and at normal atmospheric pressure forms a flammable mixture with air.

FLAMMABLE LIQUIDS

A product, material, or substance falls into Division 2 if it has a flashpoint less than 37.8°C when tested in accordance with the applicable method.

FLAMMABLE MATERIALS

A product, material, or substance falls into Division 6 of Class B if it meets either of two conditions; 1) It is spontaneously combustible under normal conditions of use and it emits a flammable gas or 2) it becomes spontaneously combustible on contact with water or water vapour.

FLAMMABLE SOLIDS

A product, material or substance is included in this division if it meets any one of four criteria that result in ignition.

FLOC

Groups or clumps of particles or coagulants and impurities that have come together and formed a cluster. Found in aeration tanks, secondary clarifiers and chemical precipitation processes.

FLOCCULATION

The gathering together of small particles to form larger particles.

FLUORESCENCE

The emission of light energy by a substance as a result of the absorption of energy from ultraviolet radiation.

FLUX

A material used to prevent, dissolve, or facilitate removal of oxides and other undesirable surface substances. Also, the measure of the quantity of magnetism, taking into account the strength and extent of the magnetic field.

FLUX DENSITY

The number of magnetic lines of flux per unit area in a magnetic field.

FOAM EXTINGUISHERS

These fire extinguishers use a cylindrical tank that is filled with sodium bicarbonate and an inner container with a solution of aluminium sulphate that combine to produce foam discharge.

FOOT VALVE

A one-way valve placed at the entrance of a suction line that is opened by the flow of water. The purpose of the valve is to prevent reverse flow.

FORCE

An action, a push or a pull, on a body that causes or tends to cause it to change its state of motion or rest, or to change its shape. (Symbol, F; unit, Newton)

FORCE OF GRAVITY

The net attraction between all masses. Gravity attracts all of the particles of a mass and the net effect of this attraction at the earth's surface is equal to 9.81 Newton’s per kilogram. The force of gravity is often called weight.

FORCED AIR TYPE FURNACE

A furnace that uses a fan to circulate the air in the system.

FORCED DRAFT SYSTEM

A boiler draft system in which combustion air is blown or forced into the combustion chamber by a fan.

FORCED FEED LUBRICATION

Where a lubricant is forced under pressure into the area to be lubricated.

FORGE WELDING

A welding process which produces the joining of metals by heating them in a forge and by applying pressure or blows.

FOUR STROKE INTERNAL COMBUSTION ENGINE

An engine that requires two revolutions of the crankshaft to complete one working cycle.

FRAME-MOUNTED PUMP

End suction centrifugal pumps designed so that the pump bearings and pump shaft are independent of the motor. This type of pump requires a coupling between the pump and the motor in order to transfer energy from the motor to the pump.

FREE BODY DIAGRAM (FBD)

A simple diagram showing all of the external forces acting on a body.

FREEZING POINT

The temperature at which a liquid will solidify or freeze upon removal of heat. The freezing point for water is 0ºC.

FREQUENCY

The number of oscillations or cycles of the sine wave produced per second expressed in Hertz (Hz).

FUEL

Material burned in a combustion chamber to release heat.

FUEL FILTER

A filter installed in fuel supply to remove dirt and other contaminants from the fuel.

FUEL INJECTOR PUMP

A plunger type pump designed to inject fuel at high pressure into the cylinder of diesel engines.

FULL SECTION

A method of cutting through the whole object in order to see one of the views (top, front, right side, left side, back or bottom).

FUSIBLE PLUG

A safety device that is made up of an alloy material that is designed to melt at a specific temperature to relieve pressure in a vessel.

GAGGING

The application of a clamp to a safety valve, during a hydrostatic pressure test, to prevent the valve from opening.

GAMMA RADIATION

Electromagnetic radiation emitted by atomic nuclei having less penetrating power than x-rays.

GAS TURBINE

A turbine that expands hot gases for the purpose of producing mechanical energy.

GAUGE GLASS

A fitting used to give a visual indication of the water level in the boiler or other vessel.

GAUGE PRESSURE

The pressure indicated by a pressure-sensing device.

GEAR-TYPE COUPLING

A mechanical coupling in which two shafts are connected through two gear hubs interconnected by a toothed sleeve.

GENERATOR

An electrical machine that converts mechanical energy into electrical energy. Also, a component of an absorption system where the refrigerant is released from the absorbent.

GOOD SAMARITAN LAWS

Laws that protect people acting in good faith when administering first aid to injured or sick casualties.

GRATE AREA

The surface upon which solid fuel (i.e. coal) rests while it is being burned.

GRAVITY TYPE FURNACE

A furnace where the heated air is circulated through the system by the force of gravity.

GREASE

A semi-solid lubricant in which oil is mixed with a thickener (i.e. soap).

GREEN LIQUOR

The smelt/water solution from the recovery boiler; the green colour comes from the combination of iron, sodium sulphide, sodium carbonate, and carbon.

GRID-TYPE COUPLING

A mechanical coupling in which a metal grid is meshed between the teeth of two shaft hubs.

GROUND WATER

All sub-surface waters, i.e., wells, springs.

HALF SECTION

Used when only half of the view is to be drawn in section and the other half is not.

HALOGEN

A compound consisting of chlorine, bromine, iodine and fluorine.

HALON EXTINGUISHERS

A gaseous extinguishing agent that does not leave residue after discharge. It works on the principle of removing the air for combustion thus extinguishing the fire.

HANDHOLE

An opening into a boiler drum or vessel that is much smaller than the manhole and is used for cleaning and inspection purposes.

HARDNESS

A property that causes the material to resist indentation or abrasion.

HAZARDOUS WASTE

Defined in WHMIS as a controlled product that is intended for disposal or is sold for recycling or recovery.

HEAD PRESSURE

The static pressure of a fluid expressed in terms of the height of a column of the fluid.

HEADER

A pipe that collects steam or water from or distributes it to a number locations.

HEADS

The ends which close off the ends of the boiler shell; may also be referred to as 'end plates' or, in fire tube boilers, as 'tube sheets'.

HEAT

A form of thermal energy due to the activity of the molecules in a mass and that can be transferred from one body to another.

HEAT EXCHANGER

Anything that transfers heat from one substance to another without allowing the substances to mix.

HEAT OF CONDENSATION

Latent heat given up in changing from a gas to a liquid.

HEAT OF FUSION

Latent heat absorbed in changing from a solid to a liquid.

HEAT PUMP

A heat transfer device that uses the heat rejected by a refrigeration process to provide heat. A combined cooling and heating unit.

HEAT RECOVERY SYSTEM

Equipment that is installed to reclaim heat that is normally lost during the blow-down process.

HEAT TRANSFER

The movement or transfer of heat from one medium to another.

HEATING LOAD

The amount of heat lost by a building through walls, roof, windows, doors, etc.

HEATING SURFACE

Parts of a boiler through which heat is transferred, from the combustion of fuel, to water or steam; the part of the boiler that has heat and combustion gases on one side and water or steam on the other.

HEATING VALUE

The amount of heat stored in a unit mass of fuel (kJ/kg).

HEAVY WATER

Water used as a cooling medium in a CANDU nuclear reactor; The hydrogen atoms that make up the water have an atomic weight of 2 due to the presence of a neutron in the nucleus.

HERMETICALLY SEALED UNIT

A refrigerating unit in which the compressor and compressor motor are sealed in the same housing, with no external shaft or shaft seal and the compressor motor operating in the refrigerant atmosphere.

HERTZ (HZ)

The SI unit of frequency equal to one cycle per second.

HIGH PRESSURE STEAM BOILER

A steam boiler operating at pressures above 103 kPa.

HIGH SIDE

The sections of a refrigeration system which operate at the high discharge pressure of a compressor or pump i.e. Condenser.

HIGHEST COMMON FACTOR (HCF)

The highest factor in which all numbers in a group can be divided into evenly without a remainder.

HOG FUEL

Waste wood used for fuel consisting mostly of bark and wood particles.

HOIST

A mechanical device used for raising and lowering heavy loads.

HORIZONTAL

Lines parallel to the horizon and at right angles to a vertical plane.

HORIZONTAL MISALIGNMENT

Parallel or angular misalignment between two shafts as viewed from above (plan view).

HOT DECK

The section of a mixed air zoning system containing the heating elements.

HOT WATER BOILER

A boiler completely filled with water, to which heat is applied to raise the temperature of the water, without generating any steam.

HOT WORK

Any task performed which may create the possibility of fire or explosion.

HOT-GAS LINE

The tube or pipe carrying the refrigerant vapour from the compressor to the condenser.

HUB

The portion of the coupling that attaches to the shaft.

HUMIDIFIER

A device that maintains the relative humidity in the building.

HUMIDIFY

To add water vapour to the air.

HUMIDISTAT

A moisture-sensing device that measures the amount of humidity in the air.

HUMIDITY

The presence of moisture in the air.

HYDRAULIC COUPLING

A coupling that connects two shafts through the motion of a fluid.

HYDROCARBON

A molecule comprised of atoms of carbon and hydrogen, i.e. a molecule of methane, CH4.

HYDROGEN SULFIDE (H2S)

A highly toxic gas that is invisible, colourless, and flammable and has an odour like rotten eggs (sulphur).

HYDROGEN-ION CONCENTRATION (H)

The weight of hydrogen ion, measured in moles per litre of solution, commonly expressed as the pH value, which is the logarithm of the reciprocal of the hydrogen-ion concentration.

HYDROSPHERE

The free water content of the planet in both solid and liquid state.

HYDROSTATIC PRESSURE

The pressure at the bottom of a column of liquid resulting from the height of the liquid in the column.

HYDROSTATIC TEST

A pressure test on a boiler or vessel to test for leaks or strength. The vessel is completely filled with water and the pressure is 1.5 times the normal working pressure.

HYGROSCOPIC

A substance that absorbs or attracts moisture from the air.

HYSTERESIS

The resistance of the magnetic domains to change direction under the influence of a changing magnetic field.

IMPELLER

The rotating element of a pump used to transfer mechanical energy from the pump to velocity energy in the water.

IMPELLER WEAR RING

A ring attached to the impeller designed to absorb wear instead of the impeller. Also provides a seal between high and low-pressure areas of the pump.

IMPINGEMENT

A situation where the flame in a boiler touches or contacts the tubes or other metal surfaces. This leads to erosion of the heating surfaces.

IMPROPER FRACTION

A common fraction with the numerator equal to or greater than the denominator. (i.e. 4/3).

IMPULSE TURBINE

A turbine that uses impulse action to change heat energy in the steam to mechanical energy.

INBOARD BEARING

The bearing closest to the impeller of an end-suction pump

INCANDESCENCE

The emission of light energy from a body as a result of raising it to a high temperature.

INCINERATION

The process of controlled burning to reduce combustible wastes to a non-combustible residue, carbon dioxide, and other gases.

INCINERATOR

A combustion chamber used to efficiently burn waste products. Also, in a gas processing plant, used to burn waste gases from the sulphur plant.

INCLUSION

Impurities enclosed within the filler material of a weld.

INCOMPLETE COMBUSTION

Combustion that is not complete; the products of combustion still contain combustible material.

INDIRECT SYSTEM

A refrigeration system in which a secondary solution, i.e. Brine, is circulated into the air or substance to be cooled, i.e. The secondary solution flows to and from the evaporator to release the heat absorbed from the air or substance being cooled.

INDUCED DRAFT

A boiler draft system where a fan at the boiler uptake is used to draw the flue gases from the boiler furnace.

INFILTRATION AIR

Air that flows into a building when exterior doors are open or when air leaks in through cracks in the building envelope.

INFLOW

Water discharged into a sewer system and service connections from sources other than regular connections. This includes flow from yard drains, foundation drains and around manhole covers. Inflow differs from infiltration in that it is a direct discharge into the sewer rather than a leak in the sewer itself.

INPUT

Information put into a communication system for transmission or into a computer system for processing; a position, terminal, or station at which input enters a system.

INPUT DEVICES

The devices at which or with the help of which, the information enters the computer system.

INSIDE SEAL

A mechanical seal whose sealing faces are placed inside of the stuffing box.

INSULATOR

A substance that is a poor conductor of electricity as a consequence of a lack of free electrons.

INTERCOOLED CYCLE

A gas turbine employing two compressors, the compressed air from the first compressor is cooled before being discharged into a second compressor.

INTERCOOLERS

Heat exchangers that remove the heat of compression from air or gas between consecutive stages of multistage compressors.

INTERCOOLING

Removal of heat from compressed gas between compression stages.

INTERLOCKS

Automatic safety switches incorporated into the boiler burner management system which will shut down the combustion process if an unsafe boiler condition exists.

INTERNAL COMBUSTION ENGINES

An engine in which the combustion process occurs within the engine itself.

INTERNAL FURNACE

Furnace that is located within the boiler and is surrounded by water.

INTERRUPTED PILOT

An automatically ignited pilot used to ignite the boiler main flame but is then automatically shut off while the boiler is running.

INVERT

To switch or reverse the numerator and the denominator, i.e., the invert of 5/9 would be 9/5.

ION

A particle, atom, or group of atoms carrying either a positive or negative charge, i.e. Na+2, SO4-2, PO4–3.

ION EXCHANGE

A process in which undesirable ions in water are exchanged with more desirable ions.

IONIZATION

The process of adding electrons to, or removing electrons from, atoms or molecules, thereby creating ions. High temperatures, electrically discharges, and nuclear radiation can cause ionization.

ISOSCELES TRIANGLE

A triangle with two equal sides and two equal angles.

JOURNAL BEARING

A type of bearing carrying a rotating shaft.

JUNCTION, COLD

The point where the wires of a thermocouple connect to the external circuit or indicating device.

JUNCTION, HOT

The joined ends of a thermocouple where heat is sensed.

KELVIN

A scientific temperature scale with graduations beginning from absolute zero, i.e. °C+273 = K

KEROSENE

A light hydrocarbon fuel or solvent.

KILOBYTE

A unit of information equal to approximately one thousand bytes.

KILOWATT (KW)

One thousand watts of power or one thousand joules of work done per second.

KILOWATT HOUR (KWH)

A unit of electrical work where one kilowatt of power is used for one hour (3600 seconds).

KINETIC ENERGY

The energy a body possesses by virtue of its motion. The kinetic energy of a body is directly proportional to its mass and its velocity squared.

KING VALVE

In a refrigeration system, a service valve located between the receiver outlet and the evaporator used to isolate either component.

KINGSBURY

A tilting pad type thrust bearing.

LABELS

In TDG, diamond shaped safety marks used on packages and small containers to indicate what type of dangerous goods are inside. Also, in WHMIS, information regarding the contents, applied to containers and packages of controlled products.

LAMINATIONS

Thin sheets of magnetic steel or iron that are used in armature and magnetic pole cores to reduce the production of eddy currents. The laminations increase the electrical resistance of the core material.

LAN

Refer to Local Area Network.

LANTERN RING

A metallic ring placed in a pump stuffing box that provides for the entrance of sealing and/or lubricating fluid to the packing.

LATENT HEAT

Heat, added or removed, from a mass that will cause a change of state at a constant temperature.

LATENT HEAT OF EVAPORATION

The heat required to change a liquid to a vapour without change in temperature.

LATENT HEAT OF FUSION

The heat quantity needed to convert a solid to a liquid without a change in temperature, i.e. 335 kJ/kg is the heat of fusion for ice.

LAY-UP

The preparation and storage of a boiler that will be out of service for an extended period of time.

LCM

Lowest common multiple. The lowest number that is evenly divisible by a group of numbers.

LEADER

A vertical drain line on multi-story buildings employed to drain storm water into the storm sewer system.

LEAK DETECTOR

A device used to detect refrigerant leaks in a refrigerating system.

LEAN AMINE

A solution of amine that has had the sour/acid gas removed.

LEL

Lower explosive limit.

LFL

Lower Flammability Limit - the minimum concentration of the refrigerant that is capable of propagating a flame through a mixture of refrigerant and air.

LIGHTING OFF

The initial ignition of fuel at boiler start-up.

LIGNIN

The binding part or glue that binds cellulose fibres together in wood.

LIGNITE

A coal with approximately 50% fixed carbon.

LIMESTONE

A sedimentary rock consisting mostly of calcium carbonate that is used to remove the impurities produced refining iron ore.

LINEAR VELOCITY

Velocity in a straight line. The units are metres /second (m/s).

LIQUID RECEIVER

A component within a refrigeration system that stores liquid refrigerant.

LITHOSPHERE

The outer layers of the earths crust and mantle.

LOAD

A force that a body or structure is subjected to. Loads may be as a result of weight such as snow on a roof, pressure such as in a boiler drum, impact such as the force on a piston during the power stroke.

LOAD CALCULATIONS

Determine the amount of heat or cooling that is required to maintain a constant temperature in a building.

LOAD TURBINE

The turbine that is directly coupled to the load in a multi-shaft gas turbine arrangement.

LOCAL AREA NETWORK (LAN)

A computer network dedicated to sharing data among several single-user workstations or personal computers.

LOW FIRE

Burning the minimum amount of fuel per unit of time.

LOW PRESSURE STEAM BOILER

A steam boiler operating at pressures at or below 103 kPa.

LOW SIDE

The section(s) of refrigeration systems that operate at the suction pressure of the compressor or pump.

LOW WATER

A condition of boiler water level in which the level is below the set point.

LOW WATER FUEL CUTOFF

A safety device that will shut off the boiler burner operation if the water level in the boiler becomes too low.

LOWEST COMMON MULTIPLE (LCM)

The lowest number that is evenly divisible by a group of numbers.

LOWEST PERMISSIBLE WATER LEVEL

The lowest water level in the boiler where the boiler can still be operated without damaging or overheating any part of the boiler.

LUMINAIRE

A device used to control the distribution of light from a lamp. Luminaries consist of the lamp, the socket, and diffusers or reflectors.

MAGNETIC COUPLING

A coupling that connects two shafts by means of a magnetic field.

MAGNETIC FLUX

A measure of the quantity of magnetism in a magnetic field.

MAGNETITE

A naturally occurring mineral (Fe3O4) that has magnetic properties such as the ability to attract other magnetic materials and is affected by the earth's magnetic field.

MAIN STEAM HEADER

The part of the system that collects steam from boilers and then distributes the steam to wherever it is needed.

MAIN STEAM STOP VALVE

The valve at the steam outlet of the boiler drum on the main steam line, used to isolate the boiler.

MAINFRAME

A large, powerful computer, often serving several connected terminals.

MAKEUP

Water added to a process to make up for losses due to leaks, blow-downs, etc.

MALLEABILITY

The property of a material that allows it to be hammered into shape without fracturing.

MANHOLE

An opening though which a person may enter the drum in order to do maintenance or inspections.

MANUAL PULL STATION

A fire alarm initiating device that requires manual activation.

MASS

The amount of matter in a body. Mass is a constant value no matter where the body is located. The mass of an astronaut in outer space remains the same as when on earth. (Symbol: m; units: kilogram, kg).

MATERIALS SAFETY DATA SHEET (MSDS)

Supplier prepared information that provides basic technical information about a product's physical characteristics and its hazardous properties.

MATTER

That which has mass and occupies space.

MAXIMUM ALLOWABLE WORKING PRESSURE (MAWP)

The maximum pressure permissible at the top of the vessel in its normal operating position, at the operating temperature specified for that pressure.

MECHANICAL ADVANTAGE

The multiplication of effort that a machine provides. It permits a heavy load to be lifted by a smaller effort.

MECHANICAL COUPLING

A coupling that connects two shafts mechanically.

MECHANICAL DRAFT

Combustion air supplied to a burner via mechanical means, such as a fan.

MECHANICAL EQUIVALENT OF HEAT

A unit of work is equal to a unit of heat (NM = J).

MECHANICAL PULPING PROCESS

In a pulp and paper mill, where grinders are used to shred wood to produce pulp that is used mainly for newsprint.

MECHANICAL REFRIGERATION SYSTEM

A term describing a refrigeration system using mechanical means to transfer energy from and to a cooling medium.

MECHANICAL SEAL

A sealing device used to control leakage from the stuffing box of a pump. Mechanical seals are usually made of two extremely smooth flat surfaces, one of which rotates on a shaft. The two flat surfaces are of such close tolerances as to prevent the passage of water between them.

MEGABYTE

In computers: a unit of information equal to approximately one million bytes.

MEGGER

An electrical instrument used to measure insulation resistance.

MELTING POINT

The temperature at which a solid changes to a liquid.

MEMORY

A unit of a computer that preserves data for retrieval; capacity for storing information.

MERCURY SWITCH

An electrical on-off switch using a pool of mercury to cover or uncover electrodes inside a glass tube as the tube is tilted.

METAL

Any of a class of chemical elements that are typically lustrous solids that are good conductors of heat and electricity.

METALLURGY

The science of production of metals from their ores.

METHYL ORANGE ALKALINITY

A test performed to measure total alkalinity of boiler water.

MICA

A silicate material having a layered structure that is flexible and elastic. It has excellent electrical insulating properties.

MICHELL THRUST BEARING

A bearing for locating the axial position of a turbine rotor. It consists of a collar on a shaft with white metal faced pads mounted on either side.

MICROCOMPUTER

A very small computer, such as a laptop or personal computer, built around a microprocessor and designed to be used by one person at a time.

MICROMETER

A measuring tool that measures inside and outside diameters, of pipe, shafts, etc.

MICRON

A unit of length. One millionth of a meter or one thousandth of a millimetre.

MICROPROCESSOR

An integrated circuit that contains the entire central processing unit of a computer on a single chip.

MIG WELDING

Also termed gas metal arc welding. An arc welding process that produces the coalescence of metals by heating them with an arc between continuous filler metal electrode and the work. Shielding is obtained from an external supplied gas source.

MINICOMPUTER

A small computer, usually fitting within a single cabinet, that has more memory and a higher execution speed than a microcomputer. It can be used by a several users at the same time.

MISALIGNMENT

A situation where the center line of two shafts do not form a perfectly straight line.

MIXED NUMBER

A whole number and a fraction combined together, i.e. 7 3/4

MIXING TANK

In a recovery boiler, a tank that combines salt cake with black liquor to replenish chemicals.

MODEM

Modulator/demodulator, a device used to transmit and receive digital data over normally analog communications lines, usually as an audio signal on telephone circuits. A modem attached to a computer performs a digital-to-analog conversion (modulation) of data and transmits them to another modem which performs a analog-to-digital conversion (demodulation) that permits its attached computer to use the data.

MODIFIERS

The basic elements are accompanied by words that describe, define, or limit other words.

MOISTURE SEPARATOR

Devices for collecting and removing moisture precipitated from steam or compressed air.

MOLECULE

A particle formed when two or more atoms are combined.

MOMENT OF A FORCE (TURNING MOMENT)

The product of the force and the perpendicular distance from the line of action of the force to the centre of rotation of the body. The moment causes or tends to cause the body to turn or rotate about a point. A rotating pump shaft is an example of a body experiencing a moment. (Symbol mom.; unit Nm)

MONOETHANNOLAMINE

A weak base solution used in the removal of sour constituents from natural gas. Referred to as amine.

MSDS

Refer to Materials Safety Data Sheet.

MUD DRUM

Lower drum of a water tube boiler.

MULTIPLE EFFECT EVAPORATORS

A series of heaters that are heated by steam to concentrate the weak black liquor into a more concentrated solution or strong black liquor of 50% concentration.

MULTIPLE-PASS BOILER

Boilers in which the flue gases make more than one pass over the heating surfaces.

NATURAL DRAFT

Where no mechanical means is used to provide air for combustion. Airflow into the combustion chamber is the result of warm air being less dense than cool air.

NATURAL GAS

A gaseous fuel comprised mainly of methane; it is found beneath the earth's surface.

NATURAL MAGNET

A naturally occurring mineral (Fe3O4) that has magnetic properties such as the ability to attract other magnetic materials and is affected by the earth's magnetic field

NEGATIVE VALENCE

Having a negative charge. Group V, VI, and VII elements on the periodic table form negative ions and tend to accept electrons.

NET POSITIVE SUCTION HEAD (NPSH)

The amount of pressure that is required on the suction side of the pump to prevent cavitation.

NETWORK

In computing, two or more computers connected for the purposed of exchanging messages and sharing data and system resources.

NEUTRALIZATION

Addition of an acid or alkali (base) to a liquid to cause the ph of the liquid to move towards a neutral pH of 7.0.

NEUTRON

A subatomic particle that has a mass almost equal to the proton but with no electronic charge, located in the nucleus of the atom.

NFPA

National Fire Protection Association.

NODE

A terminal in a computer network.

NON-FERROUS

Metal that does not contain iron.

NON-RETURN VALVE

A check valve that can be manually closed to prevent the back flow of steam from a header to a boiler.

NONCONDENSABLE GAS

Gas in a system that does not condense at the temperature and pressure at which it exists in the system.

NORMAL

In mechanics, perpendicular or at a right angle (90 degrees) to something. A normal stress is produced in a plane at 90 degrees to the force that is producing it.

NOUN

A word that names a person, place, object, event, idea, or activity.

NUCLEAR FISSION

The splitting of the atom or nucleus of the atom into subatomic particles resulting in the release of radiation and heat.

NUCLEAR WASTE

The by-product or waste from nuclear fission reactions.

NUCLEUS

The dense central core of the atom consisting of protons and neutrons.

NUMERATOR

The number above the line in a common fraction; the numerator is divided by the denominator. If four is divided by seven (4/7), then 4 is the numerator.

OBTUSE ANGLE

An angle that is greater than 90 degrees but less than 180 degrees.

OCCUPATIONAL HEALTH AND SAFETY BOARD

A provincial government board that is responsible for the regulation of workplace safety standards.

OEL

Occupational exposure limit.

OIL

A liquid form of fuel comprised of carbon, hydrogen, and varying amounts of sulphur.

OIL RING

In a bearing, a loose fitting ring that turns on a rotating shaft and hangs into an oil reservoir. As the ring turns it picks up oil and transfers it to the shaft and bearing.

OIL SEPARATOR

A device for preventing oil from entering the evaporator.

ON-OFF CONTROL

A control mechanism that has only two positions: on or off.

OPEN CIRCUIT

A circuit that is not continuous due to an open switch or a break in the conductor.

OPEN CYCLE

A gas turbine system where the gases exhaust to atmosphere.

OPEN-TYPE EXPANSION TANK

An open vessel that accommodates the expansion and contraction of liquid in a hydronic heating system as it is heated or cooled.

OPERATING SYSTEM

Software designed to control the hardware of a specific data-processing system in order to allow users and application programs to employ it easily.

ORE

A raw form of metal found in nature.

OUTBOARD BEARING

The bearing furthest from the impeller on an end-suction pump.

OVERSPEED TRIP DEVICE

A device that protects a turbine from reaching a speed higher than it is intended for by shutting off the steam (steam turbine) or fuel (gas turbine) supply.

OXIDANT

A substance that brings about oxidation in other substances.

OXIDATION

A chemical reaction with oxygen.

OXIDIZING MATERIAL

Oxidant. A product, material or substance is a controlled product within the meaning of Class C if it meets either of two conditions that causes or contributes to combustion.

PACKING

Braided or woven material placed in single rings in a stuffing box and around the pump drive shaft. It controls leakage from the stuffing box.

PACKING GLAND

A metal device placed around the drive shaft and at the rear of the stuffing box to hold the packing in place while providing enough pressure to control leakage.

PARALLEL

Lines in the same plane that are exactly the same distance apart at all points.

PARALLEL MISALIGNMENT

The misalignment of the centre-lines of two shafts so that they are not parallel. They are offset either vertical or horizontally.

PARALLELOGRAMS

Plane figures that have four straight sides; the two opposite sides are parallel, i.e., square, rectangle, rhomboid, and rhombus.

PARTICULATE MATTER

The tiny particles of solids or liquid that are in a fluid stream that may cause respiratory problems in humans and atmospheric haze (smog).

PASTEURIZATION

A process that involves the controlled heating of the milk to eliminate all pathogenic microorganisms carried in the milk that may transmit diseases to humans.

PERFECT COMBUSTION

A process that involves the controlled heating of the milk to eliminate all pathogenic microorganisms carried in the milk that may transmit diseases to humans.

PERIODIC TABLE

An organization of all the elements arranged in periods and groups that show major properties and similarities.

PERMANENT MAGNET

A ferromagnetic material whose domains have been aligned so that their magnetic poles agree and add together.

PERMEABILITY

The ease with which magnetic material will conduct lines of magnetic flux.

PERPENDICULAR

Two lines that intersect to form right angles.

PERSPECTIVE

The surfaces are shown in the same way as the eye would perceive them. Lines of an object are drawn in such a way that the parallel lines appear to converge towards one or more vanishing points.

pH

The measure of acidity or alkalinity of a substance, indicated as a number, i.e.7 = neutral, above 7 = alkaline, below 7 = acidic.

PHASE CHANGE

The change from a solid to a liquid and a liquid to a vapour or the reverse.

PHENOLPHTHALEIN

A solution which changes colour from white to red in solutions with a pH of 8.3 or greater.

PHENOLPHTHALEIN ALKALINITY

A measure of the hydroxide ions plus one half of the normal carbonate ions in aqueous suspension. Measured by the amount of sulphuric acid required to bring the water to a ph value or 8.3, as indicated by a change in colour of phenolphthalein.

PHOSPHORUS

A non-metallic chemical used to increase the mach inability of a metal.

PHOTOSYNTHESIS

A process in which organisms with the aid of chlorophyll (green plant enzyme), convert carbon dioxide and inorganic substances into oxygen and additional plant material, using sunlight for energy. All green plants grow by this process.

PHYSICAL CHANGE

A change in matter where no new type of matter is produced, i.e.; the processes of boiling, melting and freezing.

PIG IRON

A crude form of iron, combined with carbon, used to produce steel and cast iron.

PILOT

A small burner used to ignite fuel to the main burner.

PITCH

The slope of installed piping, usually given as millimetres per meter.

PITTING

Corrosion of the metal surface in a vessel often caused by the presence of oxygen.

PLACARDS

Large diamond shaped safety marks used on the outsides of vehicles or large containers to indicate what type of dangerous goods are being transported in the units.

PNEUMATIC

Any system using regulated compressed air as a working medium.

POLYPHASE

More than one phase or sine wave is generated. Some generators produce two, or more often, three phase power.

POPPING PRESSURE

Pressure at which a safety valve opens.

POROSITY

Having numerous holes or pores.

POSITIVE DISPLACEMENT COMPRESSOR

A compressor in which an increase in vapour pressure is attained by changing the internal volume of the compression chamber.

POSITIVE DISPLACEMENT PUMP

A pump in which pressure energy is added to a liquid by the action of the pump that causes a definite movement of the liquid into the discharge area.

POST PURGE

Blowing through the boiler furnace after the combustion process has been shut down in order to remove combustibles.

POTENTIAL ENERGY

In mechanics, energy of position. A body has potential energy because of its position relative to another location. For example, a rock on the edge of a cliff has potential energy relative to the ground at the cliff’s base.

POUR POINT

The lowest temperature at which a fluid will flow.

POWER

The rate of doing work measures in Watts or Joules/second.

POWER FACTOR

The ratio of true power to apparent power. A power factor of 100% is the most efficient electrical power

PPE

Personal protective equipment.

PPM

Parts per million.

PRECIPITATE

When one chemical constituent comes out of solution with another.

PRECIPITATION

The release of a material from a solution when the solubility level has been exceeded.

PRESSURE

A force applied over an area.

PRESSURE AND TEMPERATURE RELIEF VALVE

A safety device that will open if the system pressure rises above the maximum safe pressure or if the water temperature reaches 99ºCelsius.

PRESSURE DIFFERENTIAL

The difference in pressure between two pressure sources.

PRESSURE GAUGE

A fitting that indicates pressure in a system.

PRESSURE HEAD

The pressure produced by a column of liquid due to its height and density.

PRESSURE RATIO

The ratio of the absolute discharge pressure to the absolute inlet pressure in any compression cycle.

PRESSURE REGULATING VALVE

A fitting that maintains a system at a pre-determined pressure.

PRESSURE RELIEF DEVICE

A valve or rupture member designed to relieve excessive pressure automatically.

PRESSURE RELIEF VALVE

A valve held closed by a spring or other means and designed to automatically relieve excess pressure.

PRESSURE SWITCH

A pressure sensitive device that opens or closes an electrical circuit when the pressure reaches a set point, i.e. This switch may be used to start or stop a compressor when the system pressure reaches a low or high set point.

PRESSURE VESSEL

An unfired, closed vessel used for containing, storing, distributing, distilling, processing, or otherwise handling gas, vapour, or liquid exceeding the service and size limits as defined in CSA Standard B51.

PRESSURE, SATURATION

That pressure at which vapour and liquid, or vapour and solid, can co-exist in stable equilibrium.

PRESSURE-LIMITING DEVICE

A pressure responsive mechanism designed to stop automatically the refrigeration system at a predetermined pressure at a specific location.

PRESSURETROL

A boiler control device that affects the combustion process in the boiler according to the boiler steam pressure.

PRESSURIZED FURNACE

A furnace that operates above atmospheric pressure.

PREVENTATIVE MAINTENANCE

Maintenance that is carried out before a predicted malfunction or breakdown occurs.

PRIMARY AIR

Air supplied to the burner that is pre-mixed with the fuel before entering the burner.

PRIMARY WINDING

In a transformer, the winding connected to the supply circuit.

PRIME MOVER

A mechanical device that converts thermal energy directly into mechanical energy.

PRIMING

The filling of a pump with liquid before commencing pumping.

PROCESS HEAT

The heat energy taken from steam for the purpose of drying, cooking, etc.

PRODUCT

The result when two factors are multiplied together, i.e., 2 x 3 = 6; 6 is the product.

PRODUCTS OF COMBUSTION

Material formed as a result of combustion.

PROGRAMMING LANGUAGE

Syntax, grammar, and symbols or words used to give instructions to a computer.

PROPER FRACTION

A common fraction in which the numerator is a smaller number than the denominator, i.e. ½, 5/6.

PROPERTIES

Characteristics used to assist in describing or identifying substances.

PROTON

A subatomic particle, located in the nucleus of atoms, having a positive electronic charge and a mass of 1.

PSYCHROMETER (HYGROMETER)

A device used to measure humidity by comparing the wet and dry bulb temperatures of the air or space.

PSYCHROMETRIC CHART

A graph that gives the properties of air at various conditions of temperature, enthalpy, and humidity.

PSYCHROMETRY

The science dealing with air mixtures.

PULP

The cellulose material used to produce paper board and other paper products.

PULP WASHER

A device by which the lignin solution or weak black liquor is removed from the pulp.

PULVERIZED COAL

Coal that has been pulverized to a very fine consistency.

PUMP DOWN

In a Refrigeration system, the operation by which the refrigerant in a charged system is pumped into the liquid receiver.

PURGING

In a boiler, the act of blowing air through the furnace to remove any unburned fuel. In refrigeration, the act of blowing out gas from a refrigerant-containing vessel, usually for the purpose of removing non-condensables.

PUSH NIPPLE

A push nipple is a smooth piece of pipe, slightly tapered at both ends. Push nipples are used to connect radiator or cast iron boiler sections together, taking advantage of the nipple's taper to create a tight seal. Boilers and radiators whose sections are connected by push nipples make use of tie rods between the sections to hold them together.

QUADRILATERALS

Figures that have four sides, i.e., the square, rectangle, rhomboid, rhombus, trapezoid and trapezium.

QUICK-CLOSING VALVE

Valve that requires a one-quarter turn to be fully open or closed.

QUOTIENT

The result of the dividend divided by the divisor, i.e. 12 / 4 = 3 (quotient).

RADIANT HEAT

Heat transfer that uses electromagnetic waves that travel in straight lines.

RADIANT PANEL HEATERS

Panels that are embedded in the surfaces of the walls, ceilings and floors of a space for the purpose of heating. They may be electrically or hydronically heated.

RADIANT SUPERHEATER

An arrangement of tubes that absorb radiant heat from the furnace flame and transfers it to saturated steam.

RADIATION

Energy transmitted by wave motion without the need of intervening matter, i.e. Light waves.

RADIOACTIVITY

The decay of an unstable atomic nucleus or isotope.

RAM

Random Access Memory, a type of computer memory that can be accessed for both reading and writing, as opposed to ROM (Read Only Memory).

RANKIN

The absolute temperature of the imperial system with graduations beginning at absolute zero. i.e. F + 460° = °R.

RATE OF COMBUSTION

The amount of fuel being burned in the furnace per unit of time.

RAW WATER

Untreated water.

REACTION FORCE

Whenever a force acts on a body there is an equal and opposite reaction to the force produced by the body. A reaction is a force (Newton’s) that is equal to, and acts in an opposite direction to, the force. Examples of reactions are the ground supporting you by pushing back up or a rifle hitting your shoulder when it is fired.

REACTION TURBINE

A type of turbine that uses the reaction principle to convert heat energy into mechanical energy.

RECEIVER

Refer to Liquid Receiver.

RECIPROCATING COMPRESSOR

A compressor in which each compressing element consists of a piston moving back and forth in a cylinder.

RECIRCULATED AIR

The return air passed through a conditioner before being returned to the conditioned space.

RECORDER

A device that provides continuous records of measured variables with respect to time.

RECOVERY BOILER

In a pulp mill, a boiler that burns black liquor to recover the pulping chemicals and produce steam in the process.

RECTANGLE

A parallelogram with four right angles and equal opposite sides.

REFRACTORY

Temperature resistant material used in boiler furnaces for the purpose of protection around burners, lining fireboxes, sealing around openings, or making baffles.

REFRIGERANT

A fluid that is used to absorb heat at low temperature and pressure, with a change of state, and reject heat at high temperature and pressure, with a change of state.

REFRIGERATION

The process of reducing or maintaining the temperature of an area below that of the surrounding environment.

REFRIGERATION SYSTEM

A process using interconnected components that form a closed circuit in which refrigerant is circulated for the purpose of absorbing and then releasing heat for the purpose of cooling.

REGENERATIVE CYCLE

A gas turbine cycle employing a heat exchanger before discharging the gases from the gas turbine to the atmosphere.

REGENERATOR

A heat exchanger that recovers heat from exhaust fluids.

REHEATED AIR

The heating of air to a desired temperature before admittance to the air-conditioned space.

REHEATER

A tube bank used to reheat the steam to its original temperature after expanding through the high-pressure turbine before it is fed into the intermediate stage of the turbine.

RELATIVE HUMIDITY

The ratio of the amount of water vapour in the air to the amount water vapour that the air can hold at that temperature.

RELAY

A circuit device that uses a change in one electrical circuit to effect a change in another circuit by operating some control device such as a switch.

RELIEF VALVE

Refer to Pressure Relief Valve.

RELUCTANCE

The resistance that a material has to the passage of magnetic lines of flux.

RENEWABLE RESOURCES

These are sources that can be renewed at a rate higher than it is being consumed.

RESIN

A medium used to purify water.

RESISTANCE

Opposition to current flow due to the availability of valence electrons in a conductor.

REVERSE POLARITY

The arrangement of direct current arc welding leads with the work as the negative pole and the electrode as the positive pole of the welding arc.

RHOMBOID

A parallelogram with four congruent sides, opposite sides parallel, and the angles that are not 90 degrees.

RHOMBUS

A parallelogram with four congruent sides of the same length and angles that are not 90 degrees.

RICH AMINE

In a gas processing plant, a solution of amine and sour/acid gas leaving the absorption tower.

RIGGING

A method of lifting and moving heavy equipment.

RIGHT ANGLE

Angle that measures 90 degrees.

ROLLER BEARINGS

Anti-friction bearings containing rollers that are either cylindrical or spherical in shape.

ROM

Read Only Memory: a type of computer memory that can be accessed only for reading.

ROTARY PUMP

A type of positive displacement pump consisting of closely fitting elements rotating in a case. The rotation of these elements alternately draws in and discharges the liquid being pumped.

ROTATING ELEMENT

In rotary pumps these are usually called rotors, gears, screws or lobes, cam, wobble plate, sliding vanes. In centrifugal pumps they are known as impellers.

ROTOR

The rotating part of a generator that includes the shaft.

RUPTURE MEMBER OR DISC

A safety device that will rupture at a predetermined pressure.

SAFETY RELIEF VALVE

An automatic pressure-actuated relieving device suitable for use either as a safety valve or relief valve, depending on application.

SAFETY VALVE

An automatic pressure-relieving device actuated by the static pressure upstream of the valve and characterized by full-opening pop action due to the huddling chamber. It is used for gas or vapour service.

SAFETY VALVE BLOWDOWN

The difference in pressure between the popping pressure and the reseating pressure of a safety valve.

SAFETY VALVE CAPACITY

The amount of steam, in kilograms per hour, a safety valves can discharge.

SALIENT

Prominent. Salient pole rotors have multiple pairs of poles in which the pole piece and windings are prominent and obvious.

SANITARY LANDFILLING

The process of deposing of solid wastes in landfills by covering the waste with soil at the end of each day.

SANITARY SEWER

A pipe or conduit (sewer) intended to carry wastewater wastes from homes, businesses, and industries to the POTW (Publicly Owned Treatment Works). Storm water runoff or unpolluted water should be collected and transported in a separate system of pipes or conduits (storm sewers) to natural watercourses.

SANITARY SEWER SYSTEMS

A system of horizontal and vertical piping that collects wastewater from floor drains, sinks, toilets and urinals. The sewage flows through the drainage piping to a central point of disposal.

SATURATED AIR

Air that contains the maximum amount of moisture that it can hold at that temperature.

SATURATED STEAM

Steam that is fully saturated with latent heat and has no water particles present.

SATURATED VAPOR

The vapour at a certain temperature and pressure that will condense, if the pressure or temperature is lowered.

SATURATION PRESSURE

The pressure at which vapour and liquid can exist at equilibrium at a given temperature.

SATURATION TEMPERATURE

The temperature at which a liquid boils for a given pressure.

SCALAR

A quantity that has magnitude only. Mass is an example of a scalar.

SCALE

A deposit that forms on tubes reducing heat transfer efficiency.

SCALENE TRIANGLE

A triangle that has no congruent sides.

SCANNER

A device that monitors the pilot and main flame of a furnace.

SCBA

Self contained breathing apparatus.

SCOTCH MARINE BOILER

A fire tube boiler with an internal furnace.

SEAL WATER

Water applied to the stuffing box in order to seal out air and to lubricate and flush the packing.

SECONDARY AIR

Air needed to complete the combustion process, admitted near the combustion zone.

SECONDARY WINDING

In a transformer, the winding connected to the load circuit.

SECTIONAL BOILER

A boiler consisting of hollow cast iron sections bolted together.

SEDIMENT

Particles of foreign matter present in water.

SELF-PRIMING PUMP

An end-suction centrifugal pump with the suction mounted above the eye of the impeller, a recirculation port between suction and discharge, or a flap gate on the suction connection.

SEMICONDUCTOR

A solid of crystal form that has conductivity between that of a conductor and an insulator.

SENSIBLE HEAT

Heat added to or removed from a substance that will result in a change in temperature. It is heat that is sensed by a thermometer.

SEPARATOR

A pressure vessel installed in a steam pipe to separate and collect entrained condensate.

SERIES CIRCUIT

A circuit in which the parts are arranged in sequence so that the current flows through each of them in turn.

SERIES GENERATOR

A generator in which the field windings are connected in series with the armature windings so that the current induced in the armature also flows through the field windings

SET POINT

The condition (pressure, flow, temperature, etc.) that a control system is designed to maintain.

SET SQUARES

Triangular drafting tools used with a T-square to produce vertical or inclined lines.

SETTING

The brickwork surrounding the furnace in some older boiler designs. In modern boilers the setting includes the water walls, insulation, refractory and outer cladding that encloses the furnace.

SHAFT

A device used to transmit energy from the motor to its load.

SHAFT SLEEVE

A brass or stainless steel replaceable sleeve placed over the shaft where it passes through the stuffing box. Protects the shaft from wear by the packing.

SHEAR

An action that causes molecules of a body to be slid past each other. Scissors perform a shearing effect on paper. Shear force is used to punch out holes in a sheet of stainless steel. Shear stress is stress caused by a force that tends to cause particles to slide past each other.

SHELL

Consists of one or more steel plates rolled into a cylindrical form and welded together.

SHELL AND TUBE

A type of heat exchanger in which a nest or coil of tubes or pipes containing a fluid is inserted into a shell containing a second fluid. Heat is transferred from one fluid to the other through the tube or pipe walls.

SHOCK

A potentially life threatening condition that arises when there is an absence of adequate blood circulation throughout the body.

SHORT CIRCUIT

A circuit condition in which the current bypasses a section of the circuit and returns to the source.

SHRINK

Sudden reduction in boiler water level as the steam production rate is decreased.

SHROUD

The front and/or back of an impeller.

SHROUDING

A metal band that connects the outer ends of turbine blades to provide support and reduce vibration.

SHUNT

To connect in parallel or a parallel connection.

SHUNT GENERATOR

A dc generator in which the method of supplying excitation current to the field by connecting the field windings in parallel (shunt) with the generator’s output terminals.

SIGHT GLASS

A type of level indicator that provides a visual indication of the level in a vessel.

SILICA GEL

A form of oxide of silicon that adsorbs moisture readily and is used as an air-drying agent.

SIMPLE MACHINE

A device that enables the advantageous application of forces. Industrial machines are combinations of basic machines. There are three basic types of basic machines: the lever, the inclined plane, and the hydraulic press. All simple machines: pulleys, wheel and axle, block and tackle, screw jack, gears, and cams, are variations of the three basic machines.

SIMPLE SENTENCES

Sentences that contain one main, or independent, clause and contain no subordinate, or dependent clause.

SINGLE SHAFT GAS TURBINES

A gas turbine arrangement in which the compressor and the gas turbine are coupled to one shaft.

SLEEVE BEARINGS

Bearings composed of a sleeve, usually bronze, that are secured to one surface and are separated from a second surface by the lubricant.

SLING PSYCHROMETER

A device used to determine relative humidity and having two thermometers mounted in parallel; one being bare and the other covered with fabric.

SLINGER RING

A ring of leather or rubber placed around the pump shaft in back of the stuffing box. Used to protect the bearings from water leakage out of the stuffing box.

SLINGS

A cable or chain device used for lifting heavy loads.

SLOW-OPENING VALVE

Valve that requires a minimum of five full turns of its hand wheel to be fully open or closed.

SLUDGE

Accumulated residue resulting from impurities in water as it boils.

SMELT

The solution of liquid chemicals recovered from the recovery boiler.

SOFTENING

The process of elimination or reduction of calcium and magnesium in water (hardness), i.e. ion exchange.

SOFTWARE

The programs, routines, and symbolic languages that control the functioning of the hardware and direct its operation.

SOLAR GAINS

Heat gain caused by radiant energy from the sun.

SOLENOID

A coil of wire wound on a cylinder whose length is greater than its diameter. When a current is passed through the wire an electromagnetic field is produced.

SOLUTE

The substance dissolved in a solution. A solution is made up of the solvent and the solute.

SOOT

Deposits resulting from incomplete combustion of carbon.

SOOT BLOWER

A device that uses steam or air to blow soot, dust ashes, etc. from boiler tubes.

SOUR GAS

A gas that is partially composed of hydrogen sulphide.

SOURCE OF EMF

A device that develops an electromotive force.

SPALLING

Hairline cracks in boiler refractory caused by changes in furnace temperature.

SPECIFIC GRAVITY

The density of a substance compared to the density of standard material, usually water.

SPECIFIC HEAT

The quantity of heat required to change the temperature of a unit mass by one degree.

SPECIFIC VOLUME

The volume occupied by a unit mass; the basic unit is m3/kg.

SPILT CASE PUMP

A centrifugal pump designed so that the volute case is split horizontally. The case divides on a plane that cuts through the eye of the impeller.

SPONTANEOUS COMBUSTION

Self-ignition of a combustible material.

SPREADER BAR

In rigging, a bar or pipe that will distribute the weight evenly to ensure a load applied is lifted vertically.

SQUARE

A rectangle with four congruent sides and four 90 degree angles.

STABILIZATION

The process used to remove liquid condensate or gasoline from natural gas.

STABILIZER

A vessel or system used to remove the liquid condensate or gasoline from the gas stream.

STACK

A chimney that is the vertical passageway that expels flue gasses to the atmosphere well above the boiler.

STATIC EQUILIBRIUM

A state where a body does not move or rotate. The algebraic sum of the parallel forces is equal to zero and the algebraic sum of moments is equal to zero.

STATOR

The stationary part of a generator or motor.

STAY

Brace used to reinforce flat surfaces.

STAYBOLTS

Bolts used in boilers to reinforce flat surfaces to prevent bulging.

STEAM

A vapour rising from water when heat is applied.

STEAM BOILER

A closed pressure vessel in which water is converted to steam by the application of heat.

STEAM DRUM

Top drum of a steam boiler that contains both water and steam.

STEAM GAUGE

Fitting that indicates steam pressure within the boiler.

STEAM QUALITY

The ratio of the amount of latent heat present in the steam compared to the amount of latent heat that it could contain at that pressure.

STEAM SEPARATOR

Device used to increase the quality of steam, by removing entrained water.

STEAM SPACE

The space above the water level in a boiler steam drum.

STEP DOWN TRANSFORMER

A transformer that causes a reduction in voltage value and increase in current value in the secondary circuit.

STEP UP TRANSFORMER

A transformer that causes an increase in voltage value and decrease in current value in the secondary circuit.

STOP VALVE

Located immediately at the boiler and used to isolate the boiler.

STORM SEWER

A separate pipe, conduit or open channel (sewer) that carries runoff from storms, surface drainage and street wash, but does not include domestic and industrial wastes.

STORM SEWER SYSTEMS

A means for the collection and drainage of rainwater, snow melt that collects on roofs, parking lots, ramps and balconies, and sub-surface water.

STRAIGHT POLARITY

The arrangement of direct current arc welding leads in which the work is the negative pole and the electrode as the negative pole of the welding arc.

STRENGTH

Allows material to withstand high stress without deformation.

STRESS

The average of the various internal forces in a plane of area within a body as a result of the application of external forces.

STRONG BLACK LIQUOR

Weak black liquor that has had its solids content increased to 60% by the removal of liquid through the application of heat.

STUFFING BOX

That portion of the pump that houses the packing or mechanical seal. The stuffing box is usually referred to as the dry portion of the pump, and is located in back of the impeller and around the shaft.

SUBJECT

A noun or pronoun.

SUBMERGED ARC WELDING

An arc welding process that produces coalescence of metals by heating them with a bare metal electrode and the work. A blanket of granular, fusible, material shields the arc and the molten metal. Pressure is not used.

SUBMERSIBLE PUMP

End-suction, close-coupled pumps that are designed so that the pump and motor may be submersed in water.

SUCTION LIFT CONDITION

Any pump installation where the water level is below the inlet of the pump.

SUCTION LINE

The tube or pipe that carries the refrigerant vapour from the evaporator to the compressor inlet.

SULPHUR

An element, symbol S, yellow in appearance. Considered as a combustible impurity in coal.

SUMP

A sewage tank installed below the level of the lowest floor, with a submersible-type centrifugal pump that is used to pump the sewage into the public sewer main.

SUPERCOMPUTER

A mainframe computer that is among the largest, fastest, or most powerful of those available at a given time.

SUPERHEATED

The state in which a vapour is above its saturation temperature.

SUPERHEATED STEAM

Steam that has a higher temperature than the saturation temperature that corresponds to the pressure of the steam.

SURFACE BLOWDOWN VALVE

Used to remove impurities from the surface of the water in the top or steam drum.

SURFACE WATER

Water on the surface of the earth, i.e. lakes, rivers.

SURGE

A sudden increase in liquid pressure caused by a sudden reduction of flow.

SURGE DRUM

A storage chamber for low-side liquid refrigerant.

SUSPENDED SOLIDS

A mixture of fine non-settling particles in a solution that may be removed by filtering.

SWEET GAS

A gas that does not contain any sour constituents, such as hydrogen sulphide; comprised usually of methane, CH4.

SWELL

A sudden increase in boiler water level as the steam production rate is increased.

SWITCH

A switch is a device that is used to open a circuit or portion of a circuit and stop current flow.

SYNCHRONOUS SPEED

The speed at which the electromagnetic field revolves around the stator of an induction motor.

SYNTHETIC LUBRICANT

Lubricant produced by synthesis rather than from refining.

T-SQUARE

A drafting guide for drawing horizontal lines.

TAG OUT

Hanging "Do Not Operate" tags on and locking out equipment to ensure that is not operated while maintenance or inspection is carried out.

TAP

A tool used to cut internal screw threads.

TEMPERATURE

The measure of intensity and quality of heat.

TEMPERATURE/PRESSURE GAUGE

A fitting that indicates the temperature and pressure of the water leaving a hot water boiler.

TEMPORARY MAGNET

A temporary magnet is one in which the domains do not remain aligned after the magnetizing force is removed.

TENSION/TENSILE FORCES

Forces in tension, or tensile forces, are forces that are acting directly away from each other. They tend to pull the material apart.

TERMINAL

A device, often equipped with a keyboard and a video display, through which data or information can enter or leave a computer system.

THERMAL EFFICIENCY

The ratio of heat absorbed by the boiler to heat available in the fuel.

THERMAL ENERGY

Heat energy.

THERMAL GENERATING STATION

The production of electricity by using a fossil fuel.

THERMAL OIL

Oil used as a heating medium in a thermal oil heating system.

THERMOCOUPLE

A temperature-sensing device that produces an electrical signal in proportion to the temperature change.

THERMOMETER

A device used to measure the temperature of a substance.

THERMOSTAT

A device that controls the input of heat energy to maintain the pre-set temperature in the space being heated.

THERMOSTATIC EXPANSION VALVE

An expansion valve actuated by changes in superheat of the refrigerant vapour leaving the cooling unit.

THREADING DIES

A tool used to cut external screw threads.

THROTTLING

A throttle valve controlling fuel or gas flow to an engine.

THROUGH STAYS

Supports located in fire tube boilers to prevent bulging of front and rear tube sheets.

THRUST

A pushing force exerted by one mass against another, which tends to produce motion.

THRUST BEARING

A bearing designed to oppose axial thrust on a shaft.

THRUST LOADS

Loads applied along the axis of a shaft.

TIG WELDING

An arc welding process in which metals are fused by melting them with an arc between a single tungsten electrode and the work. Shielding is obtained from a gas mixture.

TITRATE

The process of adding a chemical to another solution drop by drop until an end point is reached.

TITRATION

A test method used to determine the dissolved substance concentration in a sample.

TOPPING CYCLE

When the gas turbine exhaust is directed into the furnace of a steam boiler.

TORQUE WRENCH

A wrench used to measure the torque or pressure applied to a nut or bolt.

TOTAL ENERGY

When an energy system supplies all of the electrical and the heating requirements of a defined area.

TOUGHNESS

The ability of a material to withstand a sudden impact force.

TRANSDUCER

A device that converts signals of one energy form to another.

TRANSISTOR

Electronic device used as a voltage and current amplifier, consisting of semiconductor materials that share common physical boundaries. The materials most commonly used are silicon and germanium into which impurities have been introduced.

TROUBLE SHOOTING

The process of detecting problems or potential problems through observation and testing.

TRY COCKS

Test valves on a water column used to verify the water level when the gauge glass is out of service.

TUBE SHEETS

These are the end plates of a fire tube boiler.

TUBULAR GAUGE GLASS

Round gauge glass used for lower pressures.

TUNGSTEN ELECTRODE

A non-filler metal electrode used in arc welding or cutting, made mainly from the tungsten metal.

TURBID

Having a cloudy or muddy appearance.

TURBIDITY

The measurement of the cloudiness of water due to the entrainment of suspended solids or other particles.

TURBINE

A machine that uses a medium such as water, steam, or gas to turn a wheel to produce mechanical energy.

TURNING GEAR

A turning device that assures the turbine rotor is being rotated for the purpose of even cooling after a shutdown.

TURNS RATIO

The ratio of the number of turns in the primary winding to the number of turns in the secondary winding.

TWA

Time Weighted Average (threshold limit value) - the refrigerant concentration in air for a normal 8 hour workday and a 40 hour work week to which workers may be repeatedly exposed, without health risk.

TWO STROKE INTERNAL COMBUSTION ENGINE

An engine requiring one revolution to complete one working cycle.

ULTRAVIOLET LIGHT

Electromagnetic radiation having wavelengths between that of violet light and x-rays.

UNDERFEED STOKER

A coal firing system that introduces the coal under the fire.

UNIT HEATER

A heater with electric resistance, steam, or hot water heating elements to heat the air. Natural or forced draft units are designed for wall mounting.

UNLIKE FRACTIONS

Fractions which do not have the same denominator, i.e. 1/2 and 1/3.

UNLOADER

A device in a compressor for equalizing high and low side pressures when the compressor stops and for a brief period after it starts in order to decrease the starting load on the motor.

UPFEED SYSTEM

A system in which domestic water supply enters the building in the basement and travels through horizontal pipes.

UPTAKE

The connection between the boiler and the stack.

URANIUM

An element of nature, symbol U, atomic number 92, used in the production of fuel rods for nuclear fission.

VACUUM

A pressure below atmospheric pressure.

VACUUM GAUGE

Pressure gauge used to measure pressures below the atmosphere.

VACUUM PUMPS

Low-pressure air compressors that take suction from a region below atmospheric pressure (turbine condenser) and discharge into the atmosphere.

VALENCE

The number of electrons that an atom tends to gain or lose.

VALENCE ELECTRON

An electron in the outer shell of an atom that takes part in forming chemical bonds or in the flow of electrical current.

VALVE

Any device modifying or closing off the passage of fluid through a pipe.

VANE

That portion of an impeller that throws the water toward the volute case.

VAPOUR

A gas particularly one near to equilibrium with the liquid phase of the substance. In general, any gases below its critical temperature.

VARIABLE

Any condition that may change continuously such as pressure, temperature, flow rate or level.

VECTOR

A quantity that has both magnitude and direction. The force of gravity is an example of a vector.

VELOCITY HEAD

The height of fluid equivalent to its velocity pressure.

VERB

A word that expresses physical or mental action or a state of being.

VERTEX

The common end point of the two sides of an angle.

VERTICAL LINE

A line perpendicular (90 degrees) to the horizontal.

VISCOSITY

The resistance of a liquid to flow.

VOLUMETRIC EFFICIENCY

The ratio of the actual volume of gas moved by a compressor or pump to its displacement.

VOLUTE

The spiral-shaped casing of a pump of increasing size that collects the liquid discharged by the impeller.

VORTEX

That form of movement of a mass of fluid having a whirling or circular motion that tends to form a cavity or vacuum at the center of a circle.

WAN

Refer to Wide Area Network.

WASTE HEAT BOILER

In a gas processing plant, a boiler used to combine preheated air and hydrogen sulphide gas to produce sulphur dioxide.

WASTE HEAT RECOVERY

The recovery of heat from the exhaust system of boilers, gas turbines, and other similar devices.

WATER COLUMN

A water column is a hollow forging or casting connected by pipes to the steam and water space of a boiler.

WATER COOLED CONDENSER

A condenser cooled by the increase of sensible heat of the water circulated through it.

WATER HAMMER

The concussion that results when a moving volume of liquid in a pipe is suddenly stopped.

WATER SPACE

The parts of the boiler that contain the water from which steam is generated.

WATER TUBE

Boiler tubes that have water or steam traveling through them and surrounded by hot gases.

WATER TUBE BOILER

Boiler that has water in the tubes with heat and combustion gases around the tubes.

WATER-COOLED FURNACE

A furnace that is constructed with tubes throughout its enclosure and has water circulating through the tubes for cooling purposes.

WATERLEG

A water filled section surrounding the firebox in some types of fire tube boilers.

WATERLINE

The level of water in the boiler.

WATT

The unit of power (Joule/second).

WEAK BLACK LIQUOR

The mixture of white liquor and lignin with a 15% solution of solids.

WET BULB DEPRESSION

Difference between dry bulb and wet bulb temperature.

WET RETURN

The portion of the return piping below the water line of the boiler.

WET STEAM

Steam at saturation temperature in the presence of moisture.

WET WELL

A compartment or tank in which wastewater is collected. The suction pipe of a pump may be connected to the wet well or a submersible pump may be located in the wet well.

WET WELL LIFT STATION

A lift station in which there is a single tank. Pumps can be installed in a wet well lift station in either a suction lift or suction head condition.

WET-BULB TEMPERATURE

Equilibrium temperature of water evaporating into air when the sensible heat of the air supplies the latent heat of vaporization.

WHITE LIQUOR

A chemical compound of sodium sulphide and sodium hydroxide, used for breaking down the lignin in wood.

WHMIS

Workplace Hazardous Material Information System.

WHMIS LABELS

The essential information that a person needs in order to handle a particular product safely.

WIDE AREA NETWORK (WAN)

A communication network that connects large numbers of nodes over long-distance communications links, i.e. common carrier telephone lines

WINDBOX

The pressurized ductwork or chamber that supplies combustion air to the burner(s).

WORD PROCESSOR

Computer software either specially designed for or capable of word processing, including text formatting.

WORKING FLUIDS

The substance which does the work in a heat engine; i.e., air is one of the working fluids used with gas turbines, refrigerant is the working fluid in refrigeration.

WORT

The aqueous extract made by slowly cooking the mash of malted grains and pure water during brewing.

WROUGHT IRON

Relatively pure iron produced by puddling pig iron.

ZEOLITE

A type of resin used in an ion exchange process.

ZONE

Specific section of a building that receives separate temperature control.

ZONE VALVE

A valve that regulates the flow of hot water or steam in a control zone or heating unit of a building.