Glossary Terms Book 2 Flashcards
Air Vent
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.
Condensate
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.
Radiator Trap or Steam Trap
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.
Actuator
A device used to position dampers and controls
Contact arrangement
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.
Control valve
A device used to control the flow of fluid or gas such as water, air, or steam
Controller
A device that reacts to pressure, temperature, or humidity to provide two-position, floating, or proportioning control of an actuator or relay.
Damper
A device used to control the flow of air in a duct or through a wall louvre.
Line voltage
A term that refers to the normal electric supply voltage.
Linkage
A device that connects an actuator to a damper or control valve
Extra low voltage
A term that refers to wiring or electric devices using 30 volts or less.
Relay
A device consisting of a solenoid coil, which operates load carrying contacts when the coil is energized
Transformer
A device used to change AC voltage from one value to another.
American Society of Heating,Refrigerating, and Air-Conditioning Engineers (ASHRAE)
A technical society specializing in the fields of heating, ventilation, air conditioning, and refrigeration. ASHRAE supports research and publishes standards for the HVAC industry.
Ammonia
A compound of nitrogen and hydrogen, commonly used as a refrigerant
ASME B31.5
The ASME Code that has rules for construction of refrigeration piping and heat transfer components
ASME BPVC VIIII
The ASME Boiler and Pressure Vessel Code that has rules for the construction of pressure vessels.
Backpressure Regulator
An automatic valve or control device used to maintain a set pressure, and therefore a set temperature, in an evaporator.
Compressor
A mechanical device for increasing the pressure of a gas
Cooling Medium
A substance to which a heat exchanger rejects heat
Evaporator
The part of a refrigeration system in which liquid refrigerant changes state, to produce a cooling effect.
Liquid Reciever
A pressure vessel installed in the high side of a refrigerating system for storage of liquid refrigerant.
Lithium Bromide (LiBr)
A salt (LiBr) with a high affinity for water, used to develop low pressure in the evaporator of an absorption refrigeration system.
Metering Device
Any one of several devices used to control the flow of liquid refrigerant into an evaporator.
Refrigerated Medium
The substance being cooled by a refrigerant
Refrigerant Space
The location being cooled by a refrigeration system
Saturation Pressure
The pressure at which vapour and liquid can exist in equilibrium at a given temperature.
Saturation Temperature
The temperature corresponding to a particular saturation pressure.
Halocarbon
A chlorofluorocarbon or other compound in which the hydrogen of a hydrocarbon is replaced by halogens.
Halogen
A highly reactive nonmetallic element, occupying group VIIA (17) of the periodic table, including fluorine, chlorine, bromine, and astatine.
Miscribility
The property whereby substances can be mixed together, or can dissolve into one another; in any proportion without separating.
Natural Refrigerant
A non-synthetic refrigerant, found in nature
Ozone Depleting Potential (ODP)
The ability of a refrigerant or other substance to contribute to the depletion of the Earth’s ozone layer.
Cavitation
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.
Priming
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.
