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64 Cards in this Set
- Front
- Back
- 3rd side (hint)
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When a system with a water-cooled condenser cycles off, the water regulating valve should ________. |
Close, since the head pressure is lower |
A. Remain open during the off cycle B. Close since the head pressure is lower C. Open all the way to remove any residual heat D. Re-calibrate itself to maintain the new lower head pressure |
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A normally operating water-cooled condenser is operating with a 10 degree Fahrenheit differential between water in and water out. If the amount of 85 degree fahrenheit water going through the condenser is reduced, which of the following is a possible temperature of the water leaving the condenser? |
105 degrees fahrenheit |
A. 75 degrees fahrenheit B. 0 degrees fahrenheit C. 95 degrees fahrenheit D. 105 degrees fahrenheit |
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A normally operating water-cooled condenser with a 10 degree differential between water in and water out. If scale forms on the water tubes and entering water is 85 degrees Fahrenheit, which of the following is possible? |
D. both A and B are correct |
A. The outlet water will be 88 degrees Fahrenheit B. The system head pressure will rise C. The water regulating valve will close D. both A and B are correct |
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Which of the following would allow the system to operate more efficiently? |
Condensers that have refrigerant leaving with 15 degrees of subcooling |
A. Condenser that had refrigerant leaving with 10 degrees of subcooling B. Condensers that have refrigerant leaving with 15 degrees of subcooling C. Condenser that has refrigerant leaving at 100% Vapor D. Condenser that has refrigerant leaving at 10 degrees of superheat |
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Which of the following condensers is the most efficient? |
D. Water-cooled counterflow |
A. Forced draft air-cooled B. Induced draft air-cooled C. Water-cooled parallel flow D. Water-cooled counterflow |
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An air-cooled condenser that is operating in a climate that has four distinct seasons must _______. |
A. Have some type of head preasure control |
A. Have some type of head preasure control B. Use a water regulating valve C. Have a multi circuit evaporator D. Operate with zero degrees of subcooling |
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What can be used to maintain the head pressure of a system with a water-cooled condenser? |
C. Water regulating valve |
A. Fan cycling B. Dampers and Louvers C. Water regulating valve D. All of the above |
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The refrigerant in a condenser in a refrigeration system |
B. Gives up heat |
A. Absorbs heat B. Gives up heat C. Changes to a vapor D. Is under lower pressure than the evaporator |
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The condenser in a refrigeration system _________. |
D. All of the above |
A. Desuperheats the vapor from the compressor B. Condenses the vapor from the compressor C. Subcools the liquid refrigerant before it leaves the condenser D. All of the above |
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Control of the head pressure in an air-cooled condenser is done by __________. |
D. All of the above |
A. Cycling the condenser fan B. Controlling dampers in the airstream through the condenser C. Flooding the condenser with refrigerant D. All of the above |
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Condensing temperatures in an air-cooled condensing unit can be reduced by _________. |
D. All of the above |
A. increasing the condensing surface area B. Increasing the CFM through the condenser C. Decreasing the temperature of the air entering the condenser D. All of the above |
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If the compression ratio of a system with a reciprocating compressor decreases the amount of refrigerant pumped by a compressor ________. |
A. Will increase |
A. Will increaseB. Will decrease C. Will remain the same D. Cannot be determined |
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The clearance volume of a compressor ________. |
D. Remains the same as the compression ratio decreases |
A. Increases as the compression ratio increases B. Increases as the compression ratio decreases C. Decreases as the compression ratio increases D. Remains the same as the compression ratio decreases |
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Liquid entering the compression chamber of a reciprocating compressor can lead to _______. |
D . Both A and B |
A. Damaged valves B. Damaged piston rings C. Damaged expansion valves D . Both A and B |
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Most of the heat energy in the suction Vapor entering the compressor is _______. |
C. Latent heat |
A. Heat of compression B. Sensible heat C. Latent heat D. Defrost heat |
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The screw-type compressor is used primarily in _______. |
A. Large industrial refrigeration and air-conditioning systems |
A. Large industrial refrigeration and air-conditioning systemsB. Residential air conditioningC. Small Commercial Refrigeration unitsD. Domestic refrigerators |
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The clearance volume of a compressor cylinder is the ___________. |
C. Volume of the space between the bottom of the valve plate in the top of the Piston at top dead center |
A. Amount of refrigerant Vapor the compressor cylinder will hold during each stroke B. Volume by which the compressor is rated C. Volume of the space between the bottom of the valve plate in the top of the Piston at top dead center D. Total volume of the cylinder when the Piston is at bottom dead center |
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True or false: A water regulating valve helps to maintain and systems head pressure by modulating the flow of refrigerant through the condenser |
False |
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True or false evaporative condensers operate more efficiently in climates where the wet-bulb temperature is a great deal lower than dry-bulb temperature |
True |
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True or false: The desired water flow through a condenser connected to a recirculating water system is 3 gallons per minute |
True |
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True or false: The scroll compressor is one type of reciprocating compressor |
False |
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True or false: Rotary compressors have no clearance volume |
True |
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If an air-cooled condenser fan motor stops running , the head pressure will _________ and the amount of subcooling will __________. |
Increase, decrease |
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The compression ratio for an R22 compressor operating with 68.5 PSIG suction pressure and 260 PSIG heat pressure is __________. |
3.3 |
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What is the purpose of a crankcase heater on a compressor? |
To prevent Refrigeration migration and mixing with crankcase oil, Prevents condensation of refrigerant in the compressor |
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How does the receiver ensure that only 100% liquid refrigerant enters the liquid line? |
A. By means of a dip tube |
A. By means of a dip tube B. It only allows refrigerant to enter the liquid line when it's filled with liquid C. The spring-loaded relief valve opens D. None of the above are correct |
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When a system pumps down, where is the refrigerant stored? |
D. Both a and c |
A. Receiver B. Evaporator C. Condenser D. Both a and c |
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Technician "A" says that a multi -evaporator system equipped with three evaporators (one high temperature, one medium temperature, and one low temperature) will use 1 evaporator pressure regulator and 2 flow check valve. Technician "B" says that the crankcase pressure regulator prevents the compressor from overloading on start-up. Which of the following statements is correct? |
C. Technician "A" is incorrect. Technician "B" is correct. |
A. Technician "A" is correct. Technician "B" is correct.
B. Technician "A" is correct. Technician "B" is incorrect.
C. Technician "A" is incorrect. Technician "B" is correct.
D. Technician "A" is incorrect. Technician "B" is incorrect. |
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Refrigeration systems are designed to operate year-round for this reason they are equipped with ________. |
D. Both A & B |
A. Some type of head pressure control B. Low ambient control C. Oversized evaporator coils D. Both A & B |
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As the adjusting spring on the evaporator pressure regulator is tightened, the pressure in the evaporator will _________. |
A. Increase |
A. Increase B. Decrease C. Remain the same D. Cause the Box temperature to decrease |
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A hot pull down is when ________. |
D. The load on the evaporator produces a suction pressure that increases the land on the compressor |
A. There is excess ice on the evaporator B. The condenser contains an excess amount of liquid refrigerant C. The flow of refrigerant to the evaporator is reduced D. The load on the evaporator produces a suction pressure that increases the land on the compressor |
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Which of the following is another type of low ambient temperature head pressure control? |
A. Pressure control dampers in condenser air stream |
A. Pressure control dampers in condenser air stream B. Program defrost timer C. Timer and liquid line solenoid for automatic pump down D. Compressor internal heat |
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Random defrost is accomplished _______. |
D. Occurs automatically during the off-cycle of the compressor |
A. With the timer B. Using a high pressure control C. Using a low pressure control D. Occurs automatically during the off-cycle of the compressor |
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Defrost using up internal heat is accomplished using ______. |
C. Hot gas from the compressor |
A. A sail switch B. Electronic heating elements C. Hot gas from the compressor D. Mullion heaters |
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True or false: A suction line accumulator is used to reduce the possibility of liquid refrigerant entering the compressor. |
True |
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Automatic Pump down systems are equipped with a ________ to prevent refrigerant from reaching the evaporator. |
Solenoid Valve |
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Two types of relief valves are the ________ valve and the _________ valve |
Spring loaded, one time |
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To protect a refrigeration compressor when refrigerant loss occurs a __________ control is used |
Low Pressure |
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The human body gives off heat by which of the following? |
D. All of the above |
A. Convection B. Radiation C. Conduction D. All of the above |
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If the temperature remains constant and the volume that a gas occupies increases the pressure will ________. |
A. Decrease |
A. Decrease B. Increase C. Remain the same D. Cannot be determined from the information given |
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Reciprocating compressors have ________. |
A. A piston and cylinder |
A. A piston and cylinder B. Two Scrolls that mesh together C. A rotor to compress the refrigerant D. A large fan compressor component |
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A forced draft high temperature evaporator would ________. |
D. Both A and B |
A. Have its fins very close together B. Not need to be defrosted C. Need a hot gas defrost D. Both A and B |
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Excess evaporator superheat ________. |
B. Will reduce the cooling capacity of the system |
A. Is designed to prevent liquid from entering the compressor B. Will reduce the cooling capacity of the system C. Can be removed by removing refrigerant from the system D. Will cause the system to go into defrost |
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If a low-temperature evaporator is forming excess ice, which of the following could be a possible problem? |
D. All of the above are correct |
A. The evaporator fan motor is defective B. The unit is not staying in defrost long enough C. The defrost heater is defective D. All of the above are correct |
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If a high-temperature evaporator is forming ice, which of the following is a possible problem? |
A. Evaporator fan not running |
A. Evaporator fan not running B. Compressor not running C. Condenser fan not running D. No problem, ice formation normal |
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If a low-temperature evaporator is forming ice, which of the following is a possible problem? |
D. No problem, ice formation normal |
A. Evaporator fan not running B. Compressor not running C. Condenser fan not running D. No problem, ice formation normal |
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A typically evaporator operating temperature in an air conditioning system is _______? |
A. 40 degrees Fahrenheit |
A. 40 degrees Fahrenheit B. 55 degrees Fahrenheit C. 75 degrees Fahrenheit D. 200 degrees Fahrenheit |
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A large-capacity evaporator would probably have _______. |
D. Multiple refrigerant circuits |
A. Stainless steel tubing B. An excess of liquid refrigerant C. An excess of vapor refrigerant D. Multiple refrigerant circuits |
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The primary function of an expansion device is to ________. |
D. All of the above |
A. Producer a reduction in the pressure on the liquid refrigerant B. Regulate the flow of refrigerant into the evaporator C. Lower the boiling point of the refrigerant far enough below the temperature of the load to get the needed heat transfer rate D. All of the above |
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True or false: In order for water at 60 degrees Fahrenheit to boil, it must absorb both sensible and latent heat. |
True |
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True or false: Water at 0 degrees Fahrenheit is no heat energy or molecular activity. |
False |
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True or false: The difference in the volume of two substances will determine the heat transfer rate between the substances. |
False |
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True or false: As heat is applied to a closed container containing the gas the pressure inside the container will decrease. |
False |
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True or false: Heat is a form of energy because of the motion of molecules. |
True |
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True or false: An example of a fossil fuel is hydrogen. |
False |
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True or false: Specific volume is the term used to indicate the space and weight of gas will occupy. |
True |
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True or false: A law of conservation of energy states that energy is neither created nor destroyed |
True |
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True or false:. The only location where the refrigerant vapor is superheated is in the evaporator. |
False |
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True or false: Fewer fans per inch on an evaporator allow more ice to build between defrost Cycles |
True |
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Heat that changes the temperature of a substance is called _______ heat. |
Sensible |
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Heat that causes a substance to change form is called ________ heat or sometimes ________ heat. |
Latent, Hidden |
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Two primary functions of an evaporator are to remove ________ and ________ from the refrigerated space. |
Heat, Moisture |
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The two pressures that push to close a thermostatic expansion valve are the ________ pressure and the ________ pressure. |
Spring, Evaporator |
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What are the symptoms of a capillary tube metering device system with an overcharge of refrigerant? |
Low superheat, Compressor has fluid in it |
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