Glossary Terms

Question 1

Air Vent

Answer 1

On steam heating systems, air vents are installed to allow for removal of air from all the piping, radiators, and convectors to make way for the steam. They can be manual or automatic in order to remove any air during normal operation.

Question 2

Condensate

Answer 2

When steam gives up its heat energy for some type of process such as heating, it will condense back into water or condensate. In heating systems it is usually returned to the boiler to be converted to steam again.

Question 3

Radiator Trap or Steam Trap

Answer 3

When the steam in a radiator gives up its heat to the room, it condenses into water (condensate), which must be removed as fast as it is formed. The radiator trap allows the condensate to be discharged from the radiator but prevents any steam from discharging.

Question 4

Actuator

Answer 4

A device used to position dampers and controls

Question 5

Contact arrangement

Answer 5

The electric switch configuration of a relay, controller,contactor motor started, limit switch,or other control device. Contacts that complete circuits when a relay is energized are referred to as normally open (NO) contacts. Contacts that complete electric circuits when a relay is de-energized are referred to as normally closed (NC) contacts.

Question 6

Control valve

Answer 6

A device used to control the flow of fluid or gas such as water, air, or steam

Question 7

Controller

Answer 7

A device that reacts to pressure, temperature, or humidity to provide two-position, floating, or proportioning control of an actuator or relay.

Question 8

Damper

Answer 8

A device used to control the flow of air in a duct or through a wall louvre.

Question 9

Line voltage

Answer 9

A term that refers to the normal electric supply voltage.

Question 10

Linkage

Answer 10

A device that connects an actuator to a damper or control valve

Question 11

Extra low voltage

Answer 11

A term that refers to wiring or electric devices using 30 volts or less.

Question 12

Relay

Answer 12

A device consisting of a solenoid coil, which operates load carrying contacts when the coil is energized

Question 13

Transformer

Answer 13

A device used to change AC voltage from one value to another.

Question 14

American Society of Heating,Refrigerating, and Air-Conditioning Engineers (ASHRAE)

Answer 14

A technical society specializing in the fields of heating, ventilation, air conditioning, and refrigeration. ASHRAE supports research and publishes standards for the HVAC industry.

Question 15

Ammonia

Answer 15

A compound of nitrogen and hydrogen, commonly used as a refrigerant

Question 16

ASME B31.5

Answer 16

The ASME Code that has rules for construction of refrigeration piping and heat transfer components

Question 17

ASME BPVC VIIII

Answer 17

The ASME Boiler and Pressure Vessel Code that has rules for the construction of pressure vessels.

Question 18

Backpressure Regulator

Answer 18

An automatic valve or control device used to maintain a set pressure, and therefore a set temperature, in an evaporator.

Question 19

Compressor

Answer 19

A mechanical device for increasing the pressure of a gas

Question 20

Cooling Medium

Answer 20

A substance to which a heat exchanger rejects heat

Question 21

Evaporator

Answer 21

The part of a refrigeration system in which liquid refrigerant changes state, to produce a cooling effect.

Question 22

Liquid Reciever

Answer 22

A pressure vessel installed in the high side of a refrigerating system for storage of liquid refrigerant.

Question 23

Lithium Bromide (LiBr)

Answer 23

A salt (LiBr) with a high affinity for water, used to develop low pressure in the evaporator of an absorption refrigeration system.

Question 24

Metering Device

Answer 24

Any one of several devices used to control the flow of liquid refrigerant into an evaporator.

Question 25

Refrigerated Medium

Answer 25

The substance being cooled by a refrigerant

Question 26

Refrigerant Space

Answer 26

The location being cooled by a refrigeration system

Question 27

Saturation Pressure

Answer 27

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

Question 28

Saturation Temperature

Answer 28

The temperature corresponding to a particular saturation pressure.

Question 29

Halocarbon

Answer 29

A chlorofluorocarbon or other compound in which the hydrogen of a hydrocarbon is replaced by halogens.

Question 30

Halogen

Answer 30

A highly reactive nonmetallic element, occupying group VIIA (17) of the periodic table, including fluorine, chlorine, bromine, and astatine.

Question 31

Miscribility

Answer 31

The property whereby substances can be mixed together, or can dissolve into one another; in any proportion without separating.

Question 32

Natural Refrigerant

Answer 32

A non-synthetic refrigerant, found in nature

Question 33

Ozone Depleting Potential (ODP)

Answer 33

The ability of a refrigerant or other substance to contribute to the depletion of the Earth’s ozone layer.

Question 34

Cavitation

Answer 34

When a pump is located above the source of supply there can be a negative pressure inside the pump casing. This can produce pockets of air or steam in hot water situations, which when brought into the high pressure area of the pump, can cause damage to the pump internals. These pockets produce a shock wave when they collapse. The shock waves can damage the impellers or casing, removing chunks of metal. This is avoided by having the source of supply located above the pump.

Question 35

Priming

Answer 35

Is used to remove all air from the pump head to prevent cavitational problems with the pump. The term priming, used in connection with pumps, simply means to fill the pump casing and suction line with water or with whatever liquid is being pumped.