Refrigeration test

T or F: A direct-drive compressor generally turns at a different speed from it's motor.

False

T or F: Due to its method of compression, a screw compressor does not provide discharge pressure that is as smooth or pulsation-free as that of a reciprocating compressor.

False

T or F: The shell of fully hermetic compressors are typically bolted together.

False

T or F: if the pulley on an open-drive compressor has a diameter three times greater than the pulley on the drive motor, the compressor shaft will rotate three times faster then the motor shaft.

False

T or F: in a scroll compressor, refrigerant vapor is compressed between two spinning scrolls.

False

which of the following best describes the way fully hermetic compressors are lubricated.

They are lubricated by oil circulating with the refrigerant.

T or F: The oil that circulates in the compressor removes much of the heat from the compressor and motor in hermetic units.

True

T or F: the outer diameter of a piston ring is larger than the diameter of the cylinder.

True

in rotating-vane compressors, the vanes may be brought into contact with the cylinder walls by spring pressure or by _____

centrifugal force

which of the following statements about splash lubrication systems is false.

clearances between moving parts in this type of system must be greater than in pressure systems.

attaches the piston to the crankshaft.

connecting rod

the scotch yoke type of reciprocating compressor does not use ______

connecting rods

to prevent liquid refrigerant slugging and oil slugging on compressors that operate low ambient temperature, equip it with a _____

crankcase heater.

a shaft section that is larger and has a different center from the rest of the shaft.

eccentric

compressor parts that are bolted together usually contain ______ to prevent leaks.

gaskets

In a centrifugal compressor, the spinning _____ flings refrigerant outward, compressing it against the casing,

impeller

A _____ ring helps to lubricate the cylinder wall and prevent excess lubricant from entering the cylinder.

oil

an internal unloader is typically operated by _____

oil pressure controlled by a solenoid valve

moves up and down in the cylinder to draw in, compress, and discharge the refrigerant vapor

piston

connect pistons to the connecting rods

piston pin

creates a seal between the piston and the cylinder wall

piston ring

adding refrigerant and lubricant , checking pressure, and other procedures require the use of _____

service valves

an HVACR muffler uses a _____ to reduce noise caused by gas pulsations.

set of baffles

A ______ prevents refrigerant leaks around the shaft of an open-drive compressor.

shaft seal

in scroll compressors, refrigerant typically enters the scroll from the _____ and exits out the _____

sides, center

located between the cylinder head and cylinder block

valve plate

a measure of an oil's ability to flow at given temperatures is its _____

viscosity