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8 Cards in this Set
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The two most commonly used methods of reciprocating compressor output control are: 1. Intermittent operation 2. Cylinder unloaders 3. Cylinder bypass 4. Continuous operation 1) 1, 4 2) 3, 4 3) 1, 2 4) 2, 4 5) 2, 3 |
1, 4 |
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Which of the following are refrigeration metering or flow control devices? 1. Orifice meter 2. Automatic expansion valve 3. Bourdon tube 4. Thermostat 5. Low pressure float 6. Capillary tube 1) 2, 4, 6 2) 2, 5, 6 3) 4, 5, 6 4) 1, 2, 3 5) 3, 4, 5 |
2) 2, 5, 6 |
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Which control is used to maintain a constant level of liquid refrigerant in a flooded evaporator in the liquid reserve tank? 1) A high pressure float valve 2) A low pressure float valve 3) A thermostatic expansion valve 4) A hand operated expansion valve 5) An automatic expansion valve |
A low pressure float valve |
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Manual or hand operated expansion valves are seldom used in modern refrigeration systems except for occasionally: 1) To control the temperature of the evaporator 2) To control the temperature of the condenser 3) In the bypass line around the automatic control valve 4) To control the temperature of the cooling medium 5) In the compressor oil cooling system |
In the bypass line around the automatic control valve |
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One method of controlling the capacity of reciprocating compressors is to bypass the discharge from one or more cylinders back to the suction side of the compressor. The control is called: 1) Cylinder Bypass 2) Compressor unloading 3) Sectional evaporating 4) Suction throttling 5) Dampering |
Cylinder Bypass |
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The simple control which restricts the flow of liquid from the condenser to the evaporator and maintains a pressure difference between the two units by using a considerable pressure drop resulting from resistance between the device's length and small bore is called: 1) A capillary tube 2) A bypass line 3) A high pressure float valve 4) A low pressure float valve 5) An external float chamber |
A capillary tube |
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Which of the statements about automatic expansion valves is false? 1) The control may be used with multiple cooling coils connected to the same compressor 2) The valve maintains constant pressure in the evaporator during compressor operation regardless of the load 3) A spring exerting a downward force on the diaphragm tends to open the valve 4) When the compressor stops the valve automatically shuts off 5) The spring force is counter acted by the evaporator pressure acting upward against the diaphragm that closes the valve |
The control may be used with multiple cooling coils connected to the same compressor |
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The reason for using a weighted valve pin in a high-pressure float valve system is: 1) To get proper pressure drop into the evaporator 2) To prevent flooding of the evaporator 3) To allow the room temperature to be adjusted 4) Act as a pressure relief device 5) To reduce frosting of the line immediately after the float valve |
To reduce frosting of the line immediately after the float valve |
