18.01.) When attempting to read the high pressure gauge on an operating ammonia compressor, it is noted that the pointer "hunts" (has a wide and relatively slow back and forth movement). This would most likely indicate that the compressor?
Valve action is sluggish
18.02.) Of the following statements, which one is correct regarding an engine indicator diagram?
An abnormal diagram indicates a mechanical problem with the compressor
18.03.) What type of seal is likely to be used in a small compressor?
Sleeve type
18.04.) A multi-cylinder, single acting compressor is equipped with reed type compressor valves, what type of force is used to actuate these values?
Differential pressure
18.05.) An engine indicator that is working perfectly indicates a pressure that is 20 psi below the reading of a gauge that has been installed in a system over an extended period of time. What does the difference in readings indicate?
Discharge gauge is faulty
18.06.) The cylinder of a compressor is running hot at decreased capacity. Which of the following is the most likely cause of this problem?
Broken or leaking piston rings
18.07.) In addition to malfunctioning compressor valves, what other component of a compressor could affect the relative shape of an engine indicator diagram?
Leaking pistons
18.08.) Which of the following best describes how the atmospheric reference line on an indicator diagram is used?
Determine actual pressure at any point in the diagram
18.09.) If the valve plate of a reciprocating compressor is to be replaced, what other components should be replaced at the same time?
Springs
18.10.) A system is cycling excessively, the crankcase temperature is high, discharge pressure is low and suction pressure is high, what is a possible explanation?
Faulty compressor valves
18.11.) Compressor valves control the flow of vapor into and out of a compressor's cylinders. Which of the following best describes how they are located on the valve plate?
Suction on the bottom, discharge on the top (important)
18.12.) A decrease in the capacity of a reciprocating compressor may be due to?
Leaking compressor valves
18.13.) Which of the following is not a form of compressor valve?
Disc type
18.14.) A compressor's service valves are mounted externally (on the body of the compressor), at the compressor's inlet and outlet. Where are the "compressor valves" located?
On the valve plate
18.15.) How should the seat of a service valve be positioned in order to isolate the compressor from the refrigeration circuit?
Fully front seated
18.16.) How should the seat of a service valve be positioned when a permanent pressure gauge has been installed?
Cracked off of the backseat
18.17.) During normal operation, the pressure inside of the compressor crankcase is closest to which of the following?
Evaporator pressure
18.18.) Which of the following best describes the position of the compressor's shaft seal relative to the position of the bearings?
? ask professor
18.19.) Which service valve is located at the motor end of the compressor?
Suction service valve
18.20.) What position are the compressor valves in when a particular cylinder's piston is top-dead-center?
Fully closed
18.21.) What benefit does a safety-load provide?
Prevents compressor damage caused by liquid
18.22.) Which of the following is not a function that can be performed by a compressor's service valves?
Regulate refrigerant flow
18.23.) The capacity of a compressor is a function of the amount of vapor it is capable of moving. What is the unit used to express this value?
Cubic feet per minute (cfm)
18.24.) In a modern "V" or "W" type reciprocating compressor how many cylinders are located under each head?
6
18.25.) As illustrated in a normal engine indicator diagram, which of the following correctly lists the events that take place during a compressor's suction stroke?
Re-expansion of hpv, suction valve opens, draw vapor into cylinder
18.26.) As illustrated in a normal engine indicator diagram, which of the following correctly lists the events that take place during a compressor's compression stroke?
Suction valve closes, cylinder pressure rises as piston compresses vapor, hpv is discharged
18.27.) Which of the following will determine the amount of clearance space in a particular compressor?
Physical space between the top of the piston and bottom of the valve plate
18.28.) As indicated in a normal engine indicator diagram, why does the point at which the discharge valve opens take place at a pressure which exceeds the normal head pressure?
Differential pressure causes the refrigerant to flow into the condenser
18.29.) An increased distance between the atmospheric pressure line and the bottom of an indicator diagram suggest which of the following?
Higher suction pressure
18.30.) Which of the following causes the suction compressor valve to open?
Evaporator pressure
18.31.) What type of seal is likely to be used in a midsize reciprocating compressor?
Mechanical
18.32.) How many bearings are needed at the shaft of a reciprocating compressor?
2
18.33.) Which of the following is used to create a gas tight connection between the valve plate, compressor head and compressor body?
Gasket and cement
18.34.) Which of the following is used to cool motor windings in a hermetic compressor?
Suction vapor
18.35.) Which of the following best describes how a "safety head" is held in place by?
Helical spring
18.36.) Whether it is coupled or direct connected, the shaft of the motor causes the crankshaft of the compressor to rotate. Measured in degrees of rotation, how far does the crankshaft turn in the time it takes one of the compressor's pistons to go throu
360 degrees
18.37.) Which of the following describes the term "clearance vapor"?
High pressure vapor that remains in the cylinder at the end of the compression stroke
18.38.) The engine indicator diagram has a horizontal line segment that extends from the point where the suction valve opens to the point where the compression stroke starts. This segment represents the period during which the compressor's cylinder is bei
Increased re-expansion