Compressors Multiple Choice Questions and Answers

Compressors Multiple Choice Questions and Answers Which type of screw compressor is typically used in ammonia or other high-pressure systems? Open-drive 3 multiple choice options Which of the following explains why exhaust valves present more problems than intake valves? All of the above 3 multiple choice options If a belt-driven compressor with a 6″ pulley is being turned by a motor operating at 3600 RPM and equipped with a 3″ pulley, the compressor's shaft will be turning at _____. 1800 RPM 3 multiple choice options Which of the following is a thin strip of spring steel that bends to open a valve passage and returns to a flat shape to close the passage? Reed valve. 3 multiple choice options A crankshaft that is cast with offset journals is called a(n) _____ crankshaft. crank throw-type 3 multiple choice options Which of the following types of valves has a valve stem that moves up and down in a valve guide? Poppet valves 3 multiple choice options Which of the following methods is not used to modulate the capacity of a scroll compressor? An unloader is used to hold the intake valve open so compression cannot take place. 3 multiple choice options The volume of space between the top of the piston and the valve plate when the piston is at top dead center is referred to as the _____. clearance space 3 multiple choice options A(n) ____ is used to temporarily reduce cylinder pressure during compressor start-up. unloader 3 multiple choice options Oil pumps are typically located at one end of the compressor shaft 3 multiple choice options An unloader on a reciprocating compressor reduces compressor load by holding the intake valve open 3 multiple choice options Which type of compressor is most similar in construction to an automobile engine? Reciprocating. 3 multiple choice options Reciprocating compressors can be classified by All of the above. 3 multiple choice options A ____ compressor compresses vapor between a matched set of helical rotors screw 3 multiple choice options Which of the following statements regarding poppet valves is false? Poppet valves operate more quickly than reed valves. 3 multiple choice options Which of the following statements regarding mufflers is false? Mufflers are used only on hermetic compressors. 3 multiple choice options Which of the following best explains why the electrical connections and starting relays on hermetic compressors are typically installed outside the compressor housing? Electrical arcing could break down and contaminate the refrigerant, leading to a compressor burnout. 3 multiple choice options One end of a connecting rod is attached to the piston, and the other end is attached to the crankshaft journal 3 multiple choice options In reciprocating compressors, the intake and exhaust valves are located on the valve plate 3 multiple choice options Which of the following best describes the action of a dual-capacity reciprocating compressor? One piston is on a movable eccentric. When the crankshaft reverses direction, the eccentric centers on the crankshaft, disabling the piston 3 multiple choice options Which of the following statements regarding piston rings is false? The inner diameter of a piston ring is slightly larger than the piston diameter. 3 multiple choice options Which of the following statements regarding open-drive compressors is false? Open-drive compressors are available in hermetic and semi-hermetic models. 3 multiple choice options A defrost timer that turns on defrost operations at a preset time and stops defrosting operations when the evaporator reaches a preset cut-out temperature is a ____ defrost timer. time-initiated, temperature-terminated 3 multiple choice options Heat exchangers made from two metal sheets that are welded together to form a series of passages are ____ evaporators. plate 3 multiple choice options A suction line-liquid line heat exchanger superheats vapor refrigerant in the suction line 3 multiple choice options The superheating done by a suction line-liquid line heat exchanger helps prevent liquid slugging in the compressor 3 multiple choice options Surfaces in and along air ducts that direct airflow through the evaporator and throughout the cabinet are called baffles 3 multiple choice options Which of the following statements regarding off-cycle defrost systems is false? It can only be used in very-low-temperature systems. 3 multiple choice options A condenser in which a water tubing winds around the inside of a metal refrigerant shell is called a(n) ____ condenser. shell-and-coil 3 multiple choice options A defrost timer that turns on defrost operations at a preset time and ends the defrost operation at a preset time is a ____ defrost timer. time-initiated, time-terminated 3 multiple choice options An electric heat defrost system energizes electric heating coils 3 multiple choice options Since a compressor continues to operate after a pump-down solenoid closes refrigerant from the evaporator and low side is pumped down 3 multiple choice options A defrost timer that turns on defrost operations at a preset time and turns it off when a preset pressure is reached is a ____ defrost timer time-initiated, pressure-terminated 3 multiple choice options A condensate pump is used to remove the moisture that builds up from defrosting and condensation 3 multiple choice options A liquid-cooling evaporator all of the above 3 multiple choice options In what type of defrost system is air from the conditioned space circulated over the evaporator when the compressor is not running? Off-cycle defrost system. 3 multiple choice options A condenser that consists of an inner tube through which water flows in one direction and a surrounding outer tube through which refrigerant flows in the opposite direction of the water flow is a tube-within-a-tube 3 multiple choice options Heat exchangers featuring metal fins of various styles and types connected to evaporator tubing are ____ evaporators fin-and-tube 3 multiple choice options A condenser that uses only water as the medium into which system heat is expelled is a(n) ____ condenser water-cooled 3 multiple choice options In a tube-within-a-tube condenser Both A and B. 3 multiple choice options An evaporator that depends on gravity for air circulation is a ____ evaporator natural-draft 3 multiple choice options A tank connected between the outlet of a condenser and a liquid line that is used for refrigerant storage is a(n) liquid receiver 3 multiple choice options In a nonfreezing solution defrost system all of the above 3 multiple choice options A condenser that uses only the air movement of either natural convection or forced drafts to remove heat from a system's refrigerant is a(n) ____ condenser. air-cooled 3 multiple choice options In a hot-gas defrost system, the evaporator is defrosted by refrigerant vapor from the discharge line 3 multiple choice options A condenser that is composed of a long refrigerant cylinder filled with straight copper tubes filled with cooling water is called a ____ condenser shell-and-tube 3 multiple choice options In what type of defrost system is hot refrigerant gas diverted to the evaporator to expedite the defrosting process? none of the above 3 multiple choice options The baffles used in an evaporator all of the above 3 multiple choice options Which of the following statements regarding water defrost systems is false? Water delivery may be done during a cooling cycle with the compressor running. 3 multiple choice options A hot-water reclaim tank is a cylinder filled with water that absorbs heat from refrigerant flowing through a refrigeration system's discharge line 3 multiple choice options Counterflow in a tube-within-a-tube condenser allows all of the above 3 multiple choice options Some types of water-cooled condensers use the bottom part of the shell as a liquid receiver 3 multiple choice options Metering devices that can change their orifice size to account for changes in cooling loads are referred to as ____ metering devices. modulating 3 multiple choice options A thermostatic expansion valve should reduce its flow rate as its evaporator cools 3 multiple choice options Which of the following statements regarding TXVs with bleed ports is true? none of the above 3 multiple choice options If a TXV is adjusted correctly, it will close and remain closed whenever the compressor is idle 3 multiple choice options Electronic expansion valves (EEVs) use a ____-operated assembly none of the above 3 multiple choice options The ____ inside a sensing bulb changes with the temperature at the evaporator outlet pressure of the refrigerant 3 multiple choice options Adsorption occurs when a layer of gas adheres over the surface of a solid substance 3 multiple choice options When a capillary tube serves the function of both the liquid line and the metering device, it is connected between the evaporator and the condenser 3 multiple choice options To help prevent contaminants from entering the capillary tube, a(n) ____ is usually installed at its inlet. filter-drier 3 multiple choice options The pressure reading in a system using an EEV is supplied from a ____ connected to the suction line. pressure transducer 3 multiple choice options When used with thermostatic expansion valves, the term superheat refers to the difference in temperature between the evaporator inlet and the sensing bulb 3 multiple choice options When the low-side pressure ____ in a low-side float system, a pressure control activates the compressor motor. rises 3 multiple choice options A stepper motor in an EEV can ____. all of the above 3 multiple choice options In evaporators equipped with a float pan, the suction line extends down into the float pan for the purpose of circulating oil