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
