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RMO LICENSE > Glossary > Flashcards

Glossary Flashcards

1
Q

Absolute Humidity

A

Amount of moisture in the air, indicated in the air, indicated in grains per cu. ft

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2
Q

Absolute Pressure

A

Gauge pressure plus atmospheric pressure (14.7 lb per square in.), equals absolute pressure

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3
Q

Absolute Temperature

A

Temperature measured from absolute zero.

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4
Q

Absolute Zero Temperature

A

Temperature at which all molecular motion ceases (-460 F and -275 C)

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5
Q

Absorbent

A

Substance with the ability to take up or absorb another substance

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6
Q

Absorption Refrigerator

A

Refrigerator which creates low temperatures by using the cooling effect formed when a refrigerant is absorbed by a chemical substance

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7
Q

Accumulator

A

Storage tank which receives liquid refrigerant from evaporator and prevents it from flowing into suction line before vaporizing

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8
Q

Acid Condition In System

A

Condition in which refrigerant or oil in system is mixed with fluids that are acidic in nature

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9
Q

Activated Alumina

A

Chemical form of aluminum oxide, used as a drier or dessicant

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10
Q

Activated Carbon

A

Specially processed carbon used as a filter-drier; commonly used to clean air

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11
Q

Actuator

A

That portion of a regulating valve which converts mechanical fluid, thermal energy or electrical energy into mechanical motion to open or close the valve seats

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12
Q

Adiabatic Compression

A

Compressing refrigerant gas without removing or adding heat

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13
Q

Adsorbent

A

Substance with the property to hold molecules of fluids without causing a chemical or physical change

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14
Q

Aeration

A

Process of combining substance with air

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15
Q

Agitator

A

Device used to cause motion in confined fluid

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16
Q

Air Conditioning

A

Control of the temperature, humidity, air movement, and cleaning of air in a confined space

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17
Q

Air-cooled Condenser

A

Heat of compression is transferred from condensing soils to surrounding air. This may be done by convection, fan, or blower.

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18
Q

Air Cooler

A

Mechanism designed to lower temperature of air passing through it

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19
Q

Air Diffuser

A

Air distribution outlet or grille designed to direct airflow into desired patterns

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20
Q

Air Gap

A

The space between magnetic poles or between rotating and stationary assemblies in a motor or generator

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21
Q

Air Handler

A

Fan-blower, heat transfer coil, filter, and housing parts of a system

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22
Q

Air Infiltration

A

Leakage of air into rooms through cracks, windows, doors, and other openings

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23
Q

Air-sensing Termostat

A

Thermostat unit in which sensing element is located in a refrigerated space

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24
Q

Air, standard

A

Air having a temperature of 68 F (20 C), a relative humidity of 36 percent and under pressure of 14.70 psia. The gas industry usually considers 60 F (16 C) as the temperature of standard air

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25
Q

Air Vent

A

Valve either manual or automatic, for removing air from the highest point of a could or piping assembly

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26
Q

Air Washer

A

Device used to clean air while increasing or decreasing its humidity

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27
Q

Alcohol Brine

A

Water and alcohol solution which remains a liquid below 32 F (0C)

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28
Q

Algae

A

Low form of plant life, found floating free in water

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29
Q

Allen-Type Screw

A

Screw with recessed hex shaped head

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30
Q

Alternating Current (AC)

A

Electric current in which direction of flow alternates or reverses. In 60-cycle (hertz) current, direction of flow reverses every 1/129th of a second

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31
Q

Ambient Temperature

A

Temperature of fluid (usually air) which surrounds object on all sides

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32
Q

Ammeter

A

Electric meter, calibrated in amperes, used to measure current

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33
Q

Ammonia

A

Chemical combination of nitrogen and hydrogen (NH3). Ammonia refrigerant is identified as R-717

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34
Q

Ampere

A

Unit of electric current equivalent to flow of one coulomb per second

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35
Q

Anemometer

A

Instrument for measuring the rate of airflow or motion

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36
Q

Angle Valve

A

Type of globe valve design, having pipe openings at right angles next to each other. Usually, one opening is on the horizontal plane and one is on the vertical plane.

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37
Q

Anhydrous Calcium Sulphate

A

Dry chemical made of calcium, sulfur, and oxygen (CaSO4).

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38
Q

Annealing

A

Process of heat treating metal to get desired properties of softness and ductility. (Easy to form into new shape)

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39
Q

Anode

A

Positive terminal of electrolytic cell

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40
Q

Armature

A

Part of an electric motor, generator, or other device moved by magnetism

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41
Q

Atmospheric pressure

A

Pressure that gases in air exert upon the earth; measured in pounds per square inch (grams/per square centimeter)

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42
Q

Atomize

A

Process of changing a liquid to minute particles or a fine spray

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43
Q

Automatic Control

A

Valve action reached through self-operated or self-activated means, not requiring manual adjustment

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44
Q

Automatic Defrost

A

System of removing ice and frost from evaporators automatically

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45
Q

Automatic Expansion Valve (AEV)

A

Pressure-controlled valve which reduces high-pressure liquid refrigerant to low-pressure liquid refrigerant

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46
Q

Auto Transformer

A

Transformer in which both primary and secondary cools have turns in common. Step-up or step-down of voltage is accomplished by taps on common winding.

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47
Q

Azeotropic Mixture

A

Example of azeotropic mixture-refrigerant R-502 mixture consisting of 48.8 percent refrigerant R-22, and 51.2 percent R-115. The refrigerants do not combine chemically, yet azeotropic mixture provides refrigerant characteristics desired.

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48
Q

Back Pressure

A

Pressure in low side of refrigerating system; also called suction pressure or low-side pressure

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49
Q

Back Seating

A

Fluid opening/closing such as gauge opening or to seal the joint where the valve stem goes directly through the valve body

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50
Q

Baffle

A

Plate or vans used to direct or control movement of fluid or air within confined area

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51
Q

Ball Check Valve

A

Valve assembly (ball) which permits flow of fluid in one direction only

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52
Q

Barometer

A

Instrument for measuring atmospheric pressure. It may be calibrated in pounds per square inch, in inches of mercury in a column, or millimeters

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53
Q

Baudelot Cooler

A

Heat exchanger in which water flows by gravity over the outside of the tubes or plates

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54
Q

Bearing

A

Low friction device for supporting and aligning a moving part

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55
Q

Bellows

A

Corrugated cylindrical container which moves as pressures change, or provides a seal during movement of parts

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56
Q

Bellows Seal

A

Method of sealing the valve stem. The ends of the sealing material are fastened to the bonnet and to the stem. Seal expands and contracts with the stem level.

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57
Q

Bending Spring

A

Coil spring which is placed on the inside of outside of tubing to keep it from collapsing while bending it

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58
Q

Bernouli’s Theorem

A

In a stream of liquid, the sum of elevation head, pressure head, and velocity remains constant along any life of flow provided no work is done by or upon liquid in course of its flow, and decreases in proportion to energy lost in flow.

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59
Q

Bimetal Strip

A

Temperature regulating or indicating device which works on principle that two dissimilar metals with unequal expansion rates, welded together, will bend as temperatures change

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60
Q

Bleeding

A

Slowly reducing the pressure of liquid or gas from a system or cylinder by slightly opening a valve

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61
Q

Boiling Point

A

Boiling Temperature of a liquid under a pressure of 14.7 psia (760mm)

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62
Q

Boiling Temperature

A

Temperature at which a fluid changes from a liquid to a gas

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63
Q

Booster

A

Common term applied to the use of a compressor when used as the first stage in the cascade refrigerating system

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64
Q

Bore

A

Inside diameter of a cylinder

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65
Q

Bourdon Tube

A

Thin-walled tube of elastic metal flattened and bent into circular shape, which tends to straighten as pressure inside is increased. Used in pressure gauges.

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66
Q

Boyle’s Law

A

Law of physics - volume of a gas varies as pressure varies, if temperature remains the same. Example: If absolute pressure is doubled on quantity of gas, volume is reduced by one half. If volume becomes doubled, gas has its pressure reduced by half.

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67
Q

Brazing

A

Method of joining metals with non-ferrous filler (without iron) using heat between 800 F (427 C) and melting point of the base metals

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68
Q

Brine

A

Water saturated with a chemical such as salt

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69
Q

British Temperature Unit (BTU)

A

Quantity of heat required to raise the temperature of one pound of water by one degree Fahrenheit

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70
Q

Bulb. Sensitive

A

Part of sealed fluid device which reacts to temperature. Used to measure temperature or to control a mechanism.

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71
Q

Bunker

A

Space where ice or cooling element is placed in commercial installations

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72
Q

Bypass

A

Passage at one side of, or around, a regular passage

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73
Q

Calcium Sulfate

A

Chemical compound (CaSO4) which is used as a drying agent or desiccant in liquid line driers

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74
Q

Calibrate

A

To position indicators to determine accurate measurements

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75
Q

Capacitor-Start Motor

A

Motor which has a capacitor in the starting circuit

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76
Q

Capacity

A

Refrigeration rating system, Usually measured in Btu per hour or watts (metric)

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77
Q

Carbon Dioxide

A

Compound of carbon and oxygen (CO2) which is sometimes used as a refrigerant, Refrigerant number is R-744

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78
Q

Carbon Filter

A

Air filter using activated carbon as an air cleansing agent

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79
Q

Carrene

A

Refrigerant in Group One (R-1 I) Chemical combination of carbon, chloride, and flourine

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80
Q

Cascade Systems

A

Arrangement in which two or more refrigerating systems are used in series; useus evaporator of one machine to cool condenser of other machine. Produces ultra-low temperatures.

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81
Q

Cavitation

A

Localized gaseous condition that is found within a liquid stream

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82
Q

Celsius Temperature Scale

A

Temperature scale used in metric system. Freezing point of water is 0; boiling point of water is 100

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83
Q

Centigrade Temperature Scale

A

“Temperature scale used in metric system. Freezing point of water is 0; boiling point of water is 100”

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84
Q

Centimetre

A

Metric unit of linear measurement which equals .3937 inches

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85
Q

Central Station

A

Central location of condensing unit with either wet or air-cooled condenser.
Evaporator located as needed and connected to the central condensing unit

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86
Q

Centrifugal Compressor

A

Pump which compresses gaseous refrigerants by centrifugal force

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87
Q

Change of State

A

Condition in which a substance changes from a solid to a liquid or a liquid to a gas caused by the addition of heat. Or the reverse, in which a substance changes from a gas to a liquid, or a liquid to a solid, caused by the removal of heat.

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88
Q

Charge

A

Amount of refrigerant placed in a refrigerating unit

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89
Q

Charles’ Law

A

Volume of a given mass of a gas at constant pressure varies according to its temperature

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90
Q

Check Valve

A

Device which permits fluid flow in one direction

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91
Q

Chill Factor

A

Calculated number based on temperature and wind velocity

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92
Q

Choke Tube

A

Throttling device used to maintain correct pressure difference between high side and low-side in refrigerating mechanisms.
Capillary tubes are sometimes called choke tubes

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93
Q

Circuit

A

Tubing, piping, or electrical wire installation which permits flow from the energy source back to energy sounce

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94
Q

Clearance Pocket Compressor

A

Small space in a cylinder from which compressed gas is not completely expelled. This space is called the compressor clearance space or pocket. For effective operation, compressors are designed to have as small a clearance space as possible.

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95
Q

Code Installation

A

Refrigeration or air-conditioning installation which conforms to the local code and/or the national code for safe and efficient installations.

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96
Q

Cold

A

The absence of heat; a temperature considerably below normal

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97
Q

Comfort Cooler

A

System used to reduce the temperature in the living space of homes. These systems are not complete air conditioners as they do not provide complete control of heating, humidifying, dehumidifying, and air circulation

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98
Q

Comfort Zone

A

Area on psychometric chart which shows conditions of temperature, humidity, and sometimes air movement in which people are most comfortable

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99
Q

Commutator

A

Part of rotor in electric motor which conveys electric current to rotor windings

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100
Q

Compound Gauge

A

Instrument for measuring pressures both above and below atmospheric pressure

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101
Q

Compound Refrigerating System

A

System which has several compressors or compressor cylinders in series.
The system is used to pump low-pressure vapors to condensing pressures.

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102
Q

Compression

A

Term used to denote increase of pressure on a fluid by using mechanical energy

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103
Q

Compression Gauge

A

Instrument used to measure positive pressure (pressure above atmospheric pressures) only. These gauges are usually calibrated from 0 to 300 lb. per square inch gauge, (psig) (0-21.1 kg/cm2)

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104
Q

Compression Ratio

A

Ratio of the volume of the clearance space to the total volume of the cylinder. In refrigeration it is also used as the ratio of the absolute low-side pressure to the absolute high-side pressure

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105
Q

Compressor

A

Pump of a refrigerating mechanism which draws a low pressure on cooling side of refrigerant cycle and squeezes or compresses the gas into the high-pressure or condensing side of the cycle

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106
Q

Compressor Displacement

A

Volume, in cubic inches, represented by the area of the compressor piston head or heads multiplied by the length of the stroke

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107
Q

Compressor. Hermetic

A

Compressor in which the driving motor is sealed in the same dome or housing as the compressor

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108
Q

Compressor. Multiple Stage

A

Compressor having two or more compressive steps. Discharge from each step is the intake pressure of the next in the series

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109
Q

Compressor, Open Type

A

Compressor in which the crankshaft extends through the crank-case and is driven by an outside motor. Commonly called external drive compressor

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110
Q

Compressor, Reciprocating

A

Compressor which uses a piston and cylinder mechanism to provide pumping action

111
Q

Compressor, Single-Stage

A

Compressor having only one compressive step between low-side pressure and high-side pressure

112
Q

Compressor Seal

A

Leak proof seal between crankshaft and compressor body in open type compressors

113
Q

Condensate

A

A fluid formed when a gas is cooled to its liquid state

114
Q

Condensate Pump

A

Device to remove water condensate that collects beneath an evaporator

115
Q

Condensation

A

Liquid or droplets which form when a gas or vapor is cooled below its dew point

116
Q

Condense

A

Action of changing a gas or vapor to a liquid

117
Q

Condenser

A

The part of refrigeration mechanisms which receives hot, high-pressure refrigerant gas from the compressor and cools gaseous refrigerant until it returns to its liquid state

118
Q

Condenser, Air-Cooled

A

Heat exchanger which transfers heat to surrounding air

119
Q

Condenser Fan

A

Forced air device used to move air through air-cooled condenser

120
Q

Condenser, Water-Cooled

A

Heat exchanger designed to transfer heat from hot gaseous refrigerant to water

121
Q

Condensing Pressure

A

Pressure inside a condenser at which refrigerant vapor gives up its latent heat of vaporiazation and becomes a liquid. This varies with the temperature

122
Q

Condensing Temperature

A

Temperature inside a condenser at which refrigerant vapor gives up its latent heat of liquid. This varies with the pressure

123
Q

Condensing Unit

A

Part of a refrigerating mechanism which pumps vaporized refrigerant from the evaporator, compresses it, liquefies it in the condenser, and returns it to the refrigerant control

124
Q

Conductivity

A

Ability of a substance to conduct or transmit heat and/or electricity

125
Q

Conductor

A

Substance or body capable of transmitting electricity or heat

126
Q

Contrictor

A

Tube or orifice used to restrict the flow of a gas or liquid

127
Q

Contaminant

A

Substance such as dirt, moisture, or other matter foreign to refrigerant or refrigerant oil in the system

128
Q

Continuous Cycle Absorption System

A

System which has a continuous flow of energy input

129
Q

Control

A

Automatic or manual device used to stop, start, and/or regulate flow of gas, liquid, and/or electricity

130
Q

Control, Defrosting

A

Device to automatically defrost evaporator. It may operate by means of a clock, door cycling mechanism or during “off” portion of refrigerating cycle

131
Q

Control, Low-Pressure

A

Cycling device connected to low-pressure side of system

132
Q

Control, Motor

A

Temperature of pressure operated device used to control running of motor

133
Q

Control, Pressure Motor

A

High or low pressure control connected into the electrical circuit and used to start and stop motor. It is activated by demand for refrigeration or for safety

134
Q

Control, Refrigerant

A

Device Used to regulate flow of liquid refirgerant into evaporator. Can be a capillary tube, expansion valves, or high-side and low-side float valves

135
Q

Control System

A

All of the compnents required for the automatic control of a process variable

136
Q

Control, Temperature

A

Temperature-operated thermostatic device which automatically opens or closes a circuit

137
Q

Control Valve

A

Valve which regulates the flow or pressure of a medium which affects a controlled process. Control valves are operated by remote signals from independent devices using any number of control media such as pneumatic, electric, or electro hydrualic

138
Q

Convection

A

Transfer of heat by means of movement or flow of a fluid or gas

139
Q

Convection, Forced

A

Transfer of heat resulting from forced movement of liquid or gas by means of a fan or pump

140
Q

Convection, Natural

A

Circulation of a gas or liquid due to difference in density resulting from temperature differences

141
Q

Conversion Factors

A

Force and power may be expressed in more than one way. A horse-power is equivalent to 33,000 ft. lb. of work per minute, 746 watts, or 2546 Btu per hour. These values can be used for changing horsepower into foot pounds, Brithish Thermal Units, or watts.

142
Q

Cooler

A

Heat exchanger which removes heat from a substance

143
Q

Cooling Tower

A

Device which cools by water evaporation in air. Water is cooled to wet bulb temperature of air

144
Q

Copper Plating

A

Abnormal condition developing in some units in which copper is electrolytically deposited on some compressor sufaces

145
Q

Corrosion

A

Deterioration of materials from chemical action

146
Q

Counterflow

A

Flow in opposite direction

147
Q

Couplings

A

Mechanical device joining refrigerant lines

148
Q

“Cracking” A Valve

A

Opening a valve a small amount

149
Q

Crank Throw

A

Distance between center line of main bearing journal and center line of the crankpin or eccentric

150
Q

Crankshaft Seal

A

Leak proof join between crankshaft and compressor body

151
Q

Critical Pressure

A

Compressed condition of refrigerant which gives liquid and gas the same properties

152
Q

Critical Temperature

A

Temperature at which vapor and liquid have the same properties

153
Q

Cross Charged

A

Sealed container of two fluids which together create a desired pressure-temperature curve

154
Q

Cryogenics

A

Refrigeration which deals with producing -250 F and lower

155
Q

Current

A

Transfer of electrical energy in a conductor by means of electrons changing position

156
Q

Cut In

A

The temperature value or the pressure at which the control circuit closes

157
Q

Cutout

A

Temperature value or pressure value at which the control circuit opens

158
Q

Cylinder

A

1: Device which converts fluid power into linear mechanical force and motion. The usually consists of movable elements such as a piston and piston rod, plunger, or ram, operating withing a cylindrical bore
2: Closed container for fluids

159
Q

Cylinder Head

A

Plate or cap which encloses compression end of compressor cylinder

160
Q

Cylinder, Refrigerant

A

Cylinder in which refrigerant is stored and dispensed. Color code painted on cylinder indicates kind of refrigerant

161
Q

Dalton’s Law

A

Vapor pressure created in a container by a mixture of gases is equal to the sum of individual vapor pressures of the gases contained in the mixture

162
Q

Damper

A

Device for controlling airflow

163
Q

Dearation

A

Act of separating air from substances

164
Q

Defrost Cycle

A

Refrigerating cycle in which evaporator frost and ice accumulation are melted

165
Q

Defrost Timer

A

Device connected into electrical circuit which shuts unit off long enough to permit ice and frost accumulation on evaporator to melt

166
Q

Defrosting

A

Process of removing frost accumulation from evaporators

167
Q

Degree-Day

A

Unit that represent one degree of difference from inside temperature and the average outdoor temperature for one day and is often used in estimating fuel requirements for a building

168
Q

Dehumidifier

A

Device used to remove moisture from the air

169
Q

Dehydrated Oil

A

Lubricant which has had most of its water content removed (dry oil)

170
Q

Dehydrator-Receiver

A

Small tank which serves as liquid refrigerant reservoir and which also contains a desiccant to remove moisture. Used on most automobile air conditioning installations

171
Q

De-Ice Control

A

Device for operating a refrigerating system in such a way as to provide melting of the accumulated ice and frost

172
Q

Density

A

Closeness of texture or consistency of particles within a given substance. The weight per unit volume

173
Q

Deodorizer

A

Device which absorbs or adsorbs various odors, usually by principle of absorption. Activated charcoal in commonly used

174
Q

Desiccant

A

Substance used to collect and hold moisture in refrigerating systems. A drying agent. Common desiccants are activated alumina and silica gel

175
Q

Design Pressure

A

Highest or most severe pressure expected during operation. Sometimes used as the calculated operating pressure plus an allowance for safety

176
Q

Detector, Leak

A

Device used to detect and locate refrigerant leaks

177
Q

Dew Point

A

Temperature at which vapor (at 100% humidity) begins to condense and deposit liquid

178
Q

Diaphragm

A

Flexible material usually made of thin metal, rubber, or plastic

179
Q

Dichlorodifluoromthane

A

Refrigerant commonly known as R-I2

180
Q

Dielectric Fluid

A

Fluid with high electrical resistance

181
Q

Differential

A

The temperature or pressure difference between cut-in and cut-out temperature or pressure of a control

182
Q

Direct Current (DC)

A

Electron flow which moves continuously in one direction in circuit

183
Q

Direct Expansion Evaporator

A

Evaporator using either an automatic expansion valve (AEV) or a thermostatic expansion valve (TEV) refrigerant control

184
Q

Displacement, Piston

A

Volume obtained by multiplying area of cylinder bore by length of piston stroke

185
Q

Distilling Apparatus

A

Fluid-reclaiming device used to reclaim used refrigerants. Reclaiming is usually done by vaporizing and then re-condensing refrigerant

186
Q

Double Thickness Flare

A

Copper, aluminum, or steel tubing end which has been formen into two-wall thickness, 37 to 45 degree bell mouth or flare

187
Q

Dowel Pin

A

Accurately dimensioned pin pressed into one assembly part to insure accurate alignment

188
Q

Draft Gauge

A

Instrument used to measure air

189
Q

Drier

A

Substance or device used to remove moisture from a refrigeration system

190
Q

Dry Bulb Temperature

A

Air temperature as indicated by an ordinary thermometer

191
Q

Dry Ice

A

Refrigerating substance made of solid carbon dioxide which changes directly from a solid to a gas (sublimates). Its subliming temperature is -109 F (-78 C)

192
Q

Dry System

A

Refrigeration system which has the evaporator liquid refrigerant mainly in the atomized or droplet condition

193
Q

Duct

A

Tube or channel through which air is conveyed or moved

194
Q

Eccentric

A

Device which uses high fluid velocity, such as a venturi, to create low pressure or vacuum at its throat to draw in fluid from another source

195
Q

Electric Defrosting

A

Use of electric resistance heating coils to melt ice and frost off evaporators during defrosting

196
Q

Electric Water Valve

A

Solenoid type (electrically operated) valve used to turn water flow on and off

197
Q

Electromagnet

A

Coil of wire wound around a soft iron core. When electric current flows through the wire, the assembly becomes a magnet

198
Q

Electromotive Force (EMF) Voltage

A

Electrical force which causes current (free electrons) to flow or move in an electrical circuit. Unit of measurement is the volt.

199
Q

Electronic Leak Detector

A

Electronic instrument which measures electronic flow across gas gap. Electronic flow changes indicate presence of refrigerant gas molecules

200
Q

End Bell

A

End structure or plate of electric motor which usually hold motor bearings

201
Q

Energy

A

Actual or potential ability to do work

202
Q

Enthalpy

A

Total amount of heat in one pound of a substance calculated from accepted temperature base. Temperature of 32 F (0 C) is accepted base for water vapor calculation. For refrigerator calculations, accepted base is -40 F (-40 C)

203
Q

Enthropy

A

1: Mathematical factor used in engineering calculations
2: Energy in a system

204
Q

Ethane

A

Refrigerant sometimes added to other refrigerants to improve oil circulation. Known as (R-170)

205
Q

Eutectic

A

The specific proportion of substances providing the lowest melting temperature between all possible proportions

206
Q

Eutectic Point

A

Freezing point for eutectic solutions

207
Q

Evacuation

A

Removal of air (gas) and moisture from a refrigeration or air conditioning system

208
Q

Evaporation

A

Term applied to the changing of a liquid to a gas. Heat is absorbed in this process

209
Q

Evaporative Condenser

A

Device which uses open spray or spill water to cool a condenser. Evaporation of some of the water cools the condenser water and reduces water consumption

210
Q

Evaporator

A

Part of a refrigerating system in which the refrigerant vaporizes and absorbs heat

211
Q

Evaporator, Dry Type

A

Evaporator in which the refrigerant is in the liquid droplet form

212
Q

Evaporator, Flooded

A

Evaporator containing liquid refrigerant at all times

213
Q

Evaporator Fan

A

Fan which increases air-flow over the heat exchange surface of evaporators

214
Q

Exhaust Port

A

The opening which carries the fluid to the downstream pressure of a fluid system

215
Q

Exhaust Valve

A

A movable port which provides an outlet for the cylinder gases in a compressor or engine

216
Q

Expansion Join

A

Device in piping designed to allow movement of the pie causes by the pipe’s expansion and contraction

217
Q

Expansion Valve

A

Device in refrigerating system which reduces the pressure from the high side to the low side and is operated by pressure

218
Q

Expendable Refrigerant System

A

System which discards the refrigerant after is has evaporated

219
Q

External Drive

A

Term used to indicate a compressor driven directly from the shaft or by a belt using an external motor. Compressor and motor are serviceable separately

220
Q

External Equalizer

A

Tube connected to low pressure side of a thermostatic expansion valve diaphragm and to exit end of evaporator

221
Q

Fahrenheit Scale

A

On a Fahrenheit thermometer, under standard atmospheric pressure, boiling point of water is 212 F and freezing point is 32 F

222
Q

Fail-Safe Control

A

Device which opens a circuit when sensing element loses its pressure

223
Q

Fan

A

Radial or axial flow device used for moving or producing flow of gases

224
Q

Faraday Experiment

A

Silver chloride absorbs ammonia when cooled and releases it when heated. This is the basis on which some absorption refrigerators work

225
Q

Female Thread

A

The internal thread on fittings, valves, machine bodies, and more

226
Q

Field Pole

A

Part of stator of motor which concentrates magnetic field of field winding

227
Q

Filter

A

Device for removing small foreign particles from a fluid

228
Q

Flammable Liquids

A

Liquids having a flashpoint below 140 F (60 C) and a vapor pressure not exceeding 40 psi (absolute) (2.81 kg/cm2) at 100 F (38 c)

229
Q

Flare

A

An enlargement at the end of a piece of flexible tubing by which the tubing is connected to a fitting or another piece of tubing. This enlargement is made at about a 45 degree angle. Fittings grip it firmly to make the joint leak-proof and strong

230
Q

Flare Nut

A

Fitting used to clamp tubing flare against another fitting

231
Q

Flash Gas

A

Instantaneous evaporation of some liquid refrigerant in evaporator which cools remaining liquid refrigerant to desired evaporation temperature

232
Q

Flash Point

A

Temperature at which flammable liquid will give off sufficient vapor to support a flash flame but will not support continuous combustion

233
Q

Float Valve

A

Type of valve which is operated by a sphere or pan which floats on liquid surface and controls level of liquid.

234
Q

Flooded System

A

Type of refrigerating system in which liquid refrigerant fills most of the evaporator

235
Q

Flooded System, High-Side Float

A

Refrigeration system which has a float operated by the level of the high-side liquid refrigerant

236
Q

Flooded System, Low-Side Float

A

Refrigeration system which has a low-side float refrigerant control

237
Q

Fluid

A

Substance in either a liquid or gaseous state. Substance containing particles which move and change position without separation of the mass

238
Q

Flush

A

Operation to remove and material or fluids from refrigeration system parts by pumping them to the atmosphere using refrigerant or other fluids

239
Q

Flux (Brazing, Smoldering)

A

Substance applied to surfaces to be joined by brazing or soldering to keep oxides from forming and to produce joints

240
Q

Foaming

A

Formation of a foam in an oil-refrigerant mixture due to rapid evaporation of refrigerant dissolved in the oil. This is most likely to occur when the compressor starts and the pressure is suddenly reduced

241
Q

Foot Pound

A

Unit of work. A foot pound is the amount of work done in lifting one pound one foot.

242
Q

Force

A

Force is accumulated pressure and is expressed in pounds. If the pressure is 10 psi on a plate in 10 in. sq., the force is 100 lb. If pressure is 10kg/cm2 on a plate 10 cm2 in area, the force is 100kg

243
Q

Force-Feed Oiling

A

Lubrication system which uses a pump to force oul to surfaces of moving parts

244
Q

Freeze-Up

A

1: Formation of ice in the refrigerant control device which may stop the flow of refrigerant into the evaporator
2: Frost formation on an evaporator which may stop the airflow through the evaporator

245
Q

Freezing

A

Change of state from liquid to solid

246
Q

Freezing Point

A

Temperature at which a liquid will solidify upon removal of heat. The freezing temperature for water is 32 F. (0 C) at atmospheric pressure

247
Q

Freon

A

Trade name for a family of synthetic chemical refrigerants manufactured be E. I. Dupont de Nemours & Co., Inc.

248
Q

Frost Back

A

Condition in which liquid refrigerant flows from evaporator into suction line: usually indicated by sweating or frosting of the suction line

249
Q

Frosting Type Evaporator

A

Refrigerating system which maintains the evaporator at frosting temperatures during all phases of cycle

250
Q

Frozen

A

1: Water in its solid state
2: Seized (as in machine parts) due to lack of lubrication. The term “freeze-up” us often applied to this situation

251
Q

Fusible Plug

A

Plug or fitting made with a metal of a known low temperature. Used as a safety device to release pressures in case of fire

252
Q

Galvanic Action

A

Wasting away of two unlike metals due to electrical current passing between them. The action is increased in the presence of moisture

253
Q

Gas

A

Vapor phase of a substance

254
Q

Gas-Noncondensible

A

Gas which will not form into a liquid under the operating pressure temperature conditions

255
Q

Gas Valve

A

Device in a pipeline for starting, stopping, or regulating flow of gas

256
Q

Gasket

A

Resilient (spongy) or flexible material used between mating surfaces of refrigerating unit parts or on refrigerator doors, to give a leak-proof seal

257
Q

Gasket-Foam

A

Joint sealing material made of rubber or plastic foam strips

258
Q

Gauge, Compound

A

Instrument for measuring pressures above and below atmospheric pressure

259
Q

Gauge, High Pressure

A

Instrument for measuring pressures in range of 0 psi to 500 psi (0 kg/cm2 to 35.2 kg/cm2)

260
Q

Gauge, Low Pressure

A

Instrument for measuring pressures in range of 0 psi to 50 psi (kg/cm2 to 3.52 kg/cm2)

261
Q

Gauge Manifold

A

Chamber device constructed to hold both compund and high-pressure gauges. Valves control flow of fluids through it

262
Q

Gauge Port

A

Opening or connection provided for a service technician to install a gauge

263
Q

Gauge Vacuum

A

Instrument used to measure pressures below atmospheric pressure

264
Q

Grain

A

Unit of weight and equal to 1/7000 lb. It is used to indicate the amount of moisture in the air

265
Q

Halide Torch

A

Type of torch use to safely detect halogen refrigerant leaks in system

266
Q

Halogens

A

Substance containing fluorine, chlorine, bromine, and iodine

267
Q

Head

A

Pressure, usually expressed in feet of water, inches of mercury, or millimeters of mercury

268
Q

Head, Static

A

Pressure of fluid expressed in terms of height of column of the fluid, such as water or mercury

269
Q

Head, Total Static

A

Static head from the surface of the supply source to the free discharge surface

270
Q

Head Friction

A

Heads required to overcome friction of the interior surface of a conductor and between fluid particles in motion

271
Q

Head Pressure

A

Pressure which exists in condensing side of refrigerating system

272
Q

Head Pressure Control

A

Pressure operated control which opens electrical circuit if high-side pressure becomes too high

273
Q

Head Velocity

A

Height of fluid equivalent to its velocity pressure in flowing fluid

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