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Term 1: Accessories/Oil/Piping > RACT Unit 25 Overview > Flashcards

RACT Unit 25 Overview Flashcards

1
Q

The four basic components;

  1. Must have a ________, ________, ______, and ________
  2. Other components enhance performance and reliability (controls and ________)
  3. Controls can be:
    Operational or _______ devices
    Electrical, Mechanical, or ___________ devices
A
  1. compressor, condenser, expansion device, and evaporator
  2. Controls and accessories
  3. Operational or Safety devices
    Electrical, Mechanical, or electromechanical devices
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2
Q

Mechanical Controls:

  1. Start, stop, or modulate fluid flow and can be operated by ________ or _________
  2. Almost always found in the ________
A
  1. pressure or temperature or other means

2. piping

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3
Q

Accessories enhance or improve overall system ________

A

performance

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4
Q

Evaporator Pressure Regulator (EPR):

  1. Prevents the pressure in an evaporator from ______ below a predetermined pressure
  2. Positioning controlled by ____ pressures which are ________ pressure and ______ pressure
  3. Also referred to as _____ on rise of ____ pressure
  4. Only establish a ________ pressure and do not hold a _______ pressure or limit maximum pressure
A
  1. dropping
  2. two, evaporator and spring pressure
  3. open on rise of inlet pressure valves
  4. minimum, do not hold a constant
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5
Q

Multiple Evaporator Systems:

  1. Single compressor with _______ evaporators

EPR Valves:

  1. Allow each evaporator to operate at its own ________ and __________
  2. Are equipped with ______ valves to allow gauge readings on the evaporator side of the valve
  3. Common suction-line pressure can be obtained at the compressor ________ valve
A
  1. multiple
  2. at its own pressure and temperature
  3. schrader
  4. service valves
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6
Q

Electric Evaporator Pressure-Regulating (EEPR) Valves:

  1. Provide more accurate _________
  2. Designed to maintain _______ air temperature in the refrigerated case
  3. Controlled by a bipolar ______ motor

Locations:

  1. Single evaporator: evaporator _______
  2. Multiple Evaporators: suction line before the common suction ________
A
  1. Control
  2. discharge
  3. bipolar stepper motor
  4. outlet
  5. suction line before the common suction header
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7
Q

Crankcase Pressure Regulator:

  1. Resembles an ____ valve
  2. Located close to the __________
  3. Keeps a low-temperature compressor from overloading during a ___ ____down
  4. Referred to as a ____ on rise of _____ valve
  5. Controlled by crankcase (outlet) pressure and its _______ pressure
A
  1. EPR
  2. Compressor
  3. during a hot pull down
  4. close on rise of outlet (CRO) valve
  5. spring pressure
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8
Q

Adjusting the CPR Valve:

  1. Should be accomplished on a hot pulldown or at least when the compressor has enough load that it is trying to run ________
  2. It is important to use an _______ on the compressor while adjusting the CPR valve to ensure that the amperage draw of the compressor does not exceed the full load amperage rating
A
  1. overloaded

2. ammeter

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9
Q

Oil Separators:

  1. Installed in the ________ line
  2. Separate oil from the refrigerant and return the oil to the compressor _________
  3. Oil drops fall to the bottom of the ________
  4. Oil level raises a float and opens a ______
  5. Difference between _____ and ___-side pressures push oil back to the compressor
  6. Another type is the ______ oil separator
  7. Device needs to be kept ______
A
  1. discharge line
  2. crankcase
  3. separator
  4. opens a valve
  5. high and low side
  6. helical oil separator
  7. warm
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10
Q

Vibration Eliminators:

  1. Often necessary to protect the tubing at the ______ and ________ lines
  2. Eliminated on small compressors successfully with _______ loops
  3. Large ______ requires special vibration eliminators constructed with a bellows-type lining and a flexible outer protective support
A
  1. suction and discharge lines
  2. vibration loops
  3. large tubing
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11
Q

Crankcase Heat:

The crankcase heater;

  1. Designed to help combat refrigerant ________
  2. Holds oil in the compressor’s crankcase at a temperature _______ than the coldest part of the system

Common in air-conditioning systems

  1. Can be applied in _______ ways
  2. Only needed (and desired) during the ____ _____
A
  1. migration
  2. higher
  3. several
  4. during the off-cycle
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12
Q

Oil Pumps:

  1. Larger compressors have ______ oiling systems that usually have over __ horsepower
  2. Contain an oil pump located at the end of the compressors _______
  3. Keyed into the compressors ________
  4. Can be of the gear or _______ type
  5. Squeezes the oil to a ______ pressure which is referred to as the ___ oil pressure
A
  1. forced oiling systems that usually have over 3 horsepower
  2. crankshaft
  3. crankshaft
  4. gear or eccentric type
  5. higher pressure which is referred to as the net oil pressure
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13
Q

Compressor Oil Check Valve and Partition Wall:

  1. Partition wall separates the _______ from the ______ barrel
  2. Oil-entrained suction gasses lose _______ as they enter the motor barrel and oil in the gases drop out and collects at the bottom of the _______ barrel
  3. The partition wall has an oil _____ valve and will only let oil pass to its ________
A
  1. crankcase from the motor barrel
  2. lose velocity , collects at bottom of the motor barrel
  3. oil check valve, will only let oil pass to its crankcase
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14
Q

Low Ambient Controls:

  1. Used on systems that are operated year round to maintain _____ pressure

Methods used to keep the head pressure at an acceptable level;

  1. Fan cycling using a _______ control
  2. ___ speed control
  3. Air volume control using ______ and fan cycling
  4. Condenser _______ and condenser _______
A
  1. maintain head pressure
  2. fan cycling using pressure control
  3. fan speed control
  4. air volume control using shutters and fan cycling
  5. condenser flooding and condenser splitting
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15
Q

Fan-Cycling Head Pressure Controls:

  1. Device opens on a drop in head pressure, turning condenser fan ____
  2. Device closes on a rise in _____ pressure, turning the condenser fan ___
  3. Fan cycling causes large _______ in the head pressure
  4. One application is the use of _______ fans
A
  1. off
  2. rise in head pressure, turning condenser fan on
  3. large variances
  4. multiple fans
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16
Q

Fan Speed Control for Controlling head pressure

  1. As the outside temperature _____, the fan slows down
  2. As the outside temperature rises, the fan speeds ___
  3. Some controls monitor the refrigerants condensing __________
  4. Newer generation systems use ____, to control condenser fan motor speed
A
  1. drops
  2. up
  3. temperatures
  4. VFD’s
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17
Q

Air volume Control for controlling head pressure:

  1. accomplished with a piston-driven ______ controlled with the ____-pressure refrigerant
  2. When there are multiple fans, the first fans can be cycled off using ________, and the shutter can be used on the _____ fan
A
  1. piston-driven damper controlled with high-pressure refrigerant
  2. using temperature, shutter can be used on the last fan
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18
Q

Condenser Flooding and Condenser Splitting for controlling head pressure:

  1. Condenser flooding devices cause liquid refrigerant to move from an oversized receiver to the condenser in ____ weather
  2. And requires a large amount of refrigerant to flood the _______ in the winter
  3. Splitting is another way to reduce the amount of extra ________ charge
  4. It splits the condenser into two separate _______ condenser circuits
A
  1. in cold weather
  2. condenser
  3. extra refrigerant charge
  4. two separate identical
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19
Q

Pressure Switches and Controls: Start and stop current flow to components;

  1. Low pressure switch: _____ on rise in pressure
  2. High pressure switch: ____ on rise in pressure
  3. Low ambient control: _____ on rise in pressure
  4. Oil safety switch: has a _____ delay; _____ on rise in pressure
A
  1. closes
  2. opens
  3. closes
  4. time delay, opens
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20
Q

Low pressure Switch can be used as low charge protection and _____ temperature control

A

space

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21
Q

Low pressure control applied as a thermostat:

  1. Can be set to operate the compressor the maintain the space temperature in the cooler and to serve as a ___-charge protection as well
  2. No interconnecting wires must be installed between the inside of the cooler and the _______ unit
  3. Control is rated by pressure range and ______ draw of the contacts
A
  1. low charge
  2. condensing unit
  3. current draw
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22
Q

High-pressure control:

  1. Prevents compressor from operating at high _____ pressures
  2. Opens on a ______ in pressure
  3. Can be automatically or manually ______
  4. Control cut-in point must be above the pressure corresponding to the _______ temperature
  5. Some have a fixed differential of ___psig
  6. Some manufacturers specify a manual ______
A
  1. head
  2. rise
  3. reset
  4. ambient
  5. 50psig
  6. reset
23
Q

Low-Ambient Fan Control:

Starts and stops the condenser fan motor in response to _____ pressure

A

head pressure

24
Q

Oil Pressure Safety Control:

  1. Larger compressors use with _____ pumps
  2. Pump is connected to compressor _______ and oil is forced through ______ in crankshaft
  3. Measures ___ oil pressure
A
  1. oil pumps
  2. crankshaft, holes
  3. net
25
Q

The Solenoid Valve:

  1. Valve position controlled by a solenoid ______
  2. Normally ____ or normally ______
  3. Used to control ______ or _______ flow
  4. Valves must be installed with arrow pointing in direction of ______
A
  1. coil
  2. open or closed
  3. liquid or vapour flow
  4. flow
26
Q

Automatic Pumpdown systems: Sequence of pumpdown operation;

  1. Normally closed liquid-line solenoid valve controlled by a _________
  2. Thermostat opens when desired ____ temperature is reached
  3. The solenoid deenergizes and _______
  4. Comp continues to pump ref downstream of closed solenoid valve to the high side causing low side pressure to _____
A
  1. thermostat
  2. box temp
  3. closes
  4. drop
27
Q

Automatic Pumpdown Systems: Call for Cooling:

  1. When box temp rises, thermostat ______
  2. Liquid line solenoid is _______
  3. Refrigerant flows to _______
  4. when low side pressure increases, the low pressure control _____
  5. the compressor is once again _______
A
  1. closes
  2. energized
  3. evaporator
  4. closes
  5. energized
28
Q

Defrost Cycle:

  1. Any evaporator that operates below ___F will freeze and need defrosting
  2. Hoar frost is a layer of frost and ________ air
A
  1. 32F

2. entrained air

29
Q

Medium-Temp Refrigeration:

  1. Box temperature ranges from __F to 45F
  2. Coil temps are normally 10 to ___F cooler than the box
  3. Coil temp as low as ___F
A
  1. 34 to 45F
  2. 10 to 15F
  3. 19F
30
Q

Random or Off-Cycle Defrost:

  1. Most _______ type of defrost
  2. Occurs when refrigeration system has enough reserve capacity to cool more than the _____ requirement
  3. Air in the cooler can defrost ice from the coil and evaporator fans continue to ___
A
  1. common
  2. load
  3. run
31
Q

Planned Defrost:

  1. Defrost is controlled by a ______
  2. System goes into defrost at predetermined _____
  3. Defrost cycle is initiated during low _____ periods
  4. Systems in retail establishments often go into defrost when the store is ______
A
  1. timer
  2. times
  3. load
  4. closed
32
Q

Low-Temp Evaporator Defrost:

  1. Low-temperature evaporators operate below _________
  2. Must have planned ______
  3. _____ must be added, ______ or ________ heat
A
  1. freezing
  2. defrost
  3. heat must be added, internal or external heat
33
Q

Internal heat defrost (hot gas and cool gas defrost)

  1. Cool gas comes from the top of the ________
  2. Hot gas comes from compressors _________ and the discharge gas is directed into the _________
A
  1. receiver

2. discharge and evaporator

34
Q

External Heat Defrost:

  1. Usually accomplished with _______ heaters mounted to the evaporator coil
  2. Timer controls the following events:
    - Stopping evaporator fan and compressor
    - Energizing electric heaters and drain pan heaters
  3. Temp sensor may be used to terminate _______
A
  1. electric
  3. defrost
35
Q

Defrost Termination and Fan Delay Control:

  1. Temperature-activated, single-pole-double-throw switch controlled by a remote _______ bulb
A

sensing

36
Q

Refrigeration Accessories are devices that improve system _______ and service functions

A

performance

37
Q

Each system does not have all the __________

A

accessories

38
Q

Receivers:

  1. Tank-like device located in the _______ line
  2. Used to store liquid ________ after it leaves the condenser and should be ______ than the condenser
  3. May be installed upright or __________
  4. Refrigerant must enter the _____ of the receiver and be taken from the _____ to ensure it is 100% liquid
A
  1. liquid
  2. refrigerant, lower
  3. horizontally
  4. top, bottom
39
Q

King Valve on the Receiver:

  1. Located in the liquid line between the receiver and _________ valve
  2. Normally the valve is ____seated
  3. Has a _______ port to enable readings
  4. Many systems also contain a _______ valve which stops and starts liquid flow
A
  1. expansion valve
  2. backseated
  3. service port
  4. solenoid valve
40
Q

Liquid-Line Filter Driers

  1. Located in the ______ line
  2. Removes foreign matter from the __________
  3. Connected with _______ or _______ connections
A
  1. liquid
  2. refrigerant
  3. solder or
    flare
41
Q

Refrigerant Sight Glasses:

  1. Normally located anywhere liquid flow exists and anywhere it can serve a _______
  2. When installed just prior to expansion device it enables technician to determine if a solid column of________ is reaching the device
  3. When installed at the condensing unit it can help with _________
  4. May be supplied with a moisture _________
A
  1. Purpose
  2. liquid
  3. troubleshooting
  4. indicator
42
Q

Liquid Refrigerant Distributors:

  1. Used on multi circuit ________
  2. Located at the ______ of the expansion valve
  3. Designed to allow _____ ref to flow to all circuits
A
  1. evaporators
  2. outlets
  3. equal
43
Q

Heat Exchangers:

  1. May be placed in or at the ______ line leaving the evaporator
  2. Suction and liquid lines are connected to allow _____ to transfer between them
  3. Increase the amount of ________ in the liquid entering the expansion device
  4. Prevents liquid refrigerant from moving through the suction line into the __________
A
  1. suction line
  2. heat
  3. sub cooling
  4. compressor
44
Q

Suction Line Accumulators:

  1. Prevents liquid refrigerant from entering the __________
  2. Gives liquid a place to ________ before entering the compressor
  3. Should have adequate liquid holding ________
A
  1. compressor
  2. vaporize
  3. capacity
45
Q

Suction-Filter Driers:

  1. Good compressor ________
  2. Must be installed when system has become _________
  3. Most have some means for determining the _______ drop across the cores because even a small
    pressure drop can reduce the _______ of the compressor
A
  1. protection
  2. contaminated
  3. pressure drop, efficiency
46
Q

Refrigerant Check Valves:

  1. Allow refrigerant to flow in ____ direction
  2. Can be either the ____ type or magnetic type
  3. Must be installed with arrow pointing in the direction of refrigerant _____
  4. Cause some pressure drop, even when ______
A
  1. one
  2. ball type
  3. flow
  4. open
47
Q

Suction Service Valves:

  1. Normally attached to the _________
  2. Can never be totally _______
  3. Positions: ____seated, front______ and ___seated
A
  1. compressor
  2. closed
  3. front-seated, back-seated, mid-seated
48
Q

Discharge Service Valves:

  1. Located in the ________ line
  2. Used as a gauge port and to valve off the compressor for _______
  3. Should not be ____seated when the compressor is running except during closed-loop capacity tests
A
  1. discharge
  2. service
  3. front seated
49
Q

Refrigeration Line service valves:

  1. Hand-operated speciality valves used for ________ purposes
  2. Used in any line that may have to be valved ____ for any reason
  3. Two types: Diaphragm valve and ____ valve
A
  1. service
  2. off
  3. ball valve
50
Q

Diaphragm Valves:

  1. Same internal flow pattern as a _____ valve
  2. Can be tightened by hand enough to hold back _____ pressures
  3. Installed into the system with either a flare or ______ connection
A
  1. globe
  2. high
  3. flare or soldered
51
Q

Ball Valves:

  1. Straight-through valve with little pressure _____
  2. Advantage is that it can be opened or closed easily because it only takes a ___degree turn to either open or close it
  3. Known as a “quick open or close”
    _____
A
  1. drop
  2. 90 degree
  3. valve
52
Q

Pressure Access Ports:

  1. Used for taking pressure readings at places that do not have _____ ports
  2. ______ the line when attached
  3. Some can be attached while the unit is operating, may be _____ or ______ to the line
A
  1. service
  2. pierce
  3. bolted or soldered
53
Q

Relief Valves:

Release refrigerant from a system when predetermined ____-pressures exist

A

high

Term 1: Accessories/Oil/Piping (9 decks)

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