MOD 19 missed questions

if a belt-driven compressor with 6" pulley is being turned by a motor operating at 3600 RPM and equipped with a 2" pulley, the compressors shaft will be turning at

1800 RPM

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

oil pumps are typically located

at one end of the compressor shaft

a crankshaft that is cast with offset journals is called a ___ crankshaft

crank throw-type

one end of a connecting rod is attached to the piston, and the other end is attached to the

crankshaft journal

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

a compressor with a splash lubrication system must have greater clearances that a compressor with a pressure lubrication system T or F

false

a crankshaft and connecting rods convert the rotary motion of the motor shaft to rotary motion of the pistions T or F

false

all hermetic compressors require a crankshaft seal T or F

false

in a pressure lubrication system, the crank throw dips into the oil at each crankshaft revolution T or F

false

in a water-cooled compressor, Coll water is sprayed onto the motor windings inside the compressor dome T or F

false

the component that connects the crankshaft to the piston is the shaft seal T or F

false

the reed valve type of reciprocating compressor has long piston with an elliptical slot in the bottom of the piston skirt T or F

false

an unloader on a reciprocating compressor reduces compressor load by

holding the intake valve open

which of the following statements regarding mufflers is false

mufflers are only used on hermetic compressors

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

Which type of screw compressor is typically used in ammonia or other high-pressure systems

open-drive

which of the following statements regarding open-drive compressors is false

open-drive compressors are available in hermetic and semi-hermetic models

which of the following types of valves has a valve stem that moves up and down in a valve guide

poppet valves

which of the following statements regarding poppet vales is FALSE

poppet valves operate more quickly than reed valves

which of the following is a thin strip of spring steel that bends to a open a calve passage and returns to a flat shape to close the passage

reed valve

a ___ compressor compresses vapor between a matched set of helical rotors

screw

a full-floating piston pin is free to turn in both the connecting rod busing and the piston bushings T or F

true

an open-drive and semi-hermetic compressors, the mating surfaces between bolted parts are usually sealed with gaskets T or F

true

the purpose of the cylinder head is to support the valve plate and to seal the cylinder so compression can occur T or F

true

the types of unloader mechanisms and controls used on screw compressors can provide variable unloading T or F

true

the vanes on a rotating vane compressor may be brought into contact with the cylinder walls by spring pressure or centrifugal force T or F

true

in reciprocating compressors, the intake and exhaust valves are located on the

valve plate