Course outline

 Introduction to Compressors

• List the five kinds of air conditioning and refrigeration compressors.

• Contrast the operation of positive-displacement and kinetic-displacement compressors.

• Explain how each kind of the five kinds of compressor raises the pressure of the refrigerant vapor.

• Define staging and cascading and explain why each is used.

• List important considerations in compressor replacement.

Reciprocating Compressors

• Describe the general construction of open, semi-hermetic, and full-hermetic reciprocating compressors.

• Explain how the basic parts of a reciprocating compressor are assembled.

• Identify common designs of housings, pistons, connecting rods, crankshafts, bearings, seals, cylinder heads, and valves used in reciprocating

• Compressors.

• Explain how a cylinder unloader controls the capacity of a reciprocating compressor.

• Explain how compressors are lubricated.

• Explain how compressor vibration and noise are controlled.

Rotary, Helical, and Scroll Compressors

• Describe the operation of single-vane and multiple-vane rotary compressors, including how each raises refrigerant pressure.

• List several advantages of rotary compressors over reciprocating compressors.

• Define slugging and cavitation.

• Tell the two functions of an accumulator in a rotary compressor.

• Compare and contrast rotary and helical compressors.

• Describe the operation of the single-screw and twin-screw helical compressor.

• Describe the operation of a scroll compressor.

Centrifugal Compressors

• Describe the operating principle of a kinetic-displacement compressor.

• List advantages and disadvantages of centrifugal compressors as compared to positive-displacement types.

• Explain reverse hydrostatic sealing.

• Explain how centrifugal compressors deal with thrust forces.

• Trace the operation of a typical centrifugal compressor lubrication system.

• Tell the purpose of a purge system.

• Describe the capacity control methods used in centrifugal compressors.

Compressor Motors

• Explain the basic requirements of a compressor motor.

• Name the different types of single-phase and three-phase motors used to power compressors and tell which ones can be used in hermetic

• Compressors.

• Explain how to reverse the direction of rotation of a motor.

• Explain how to change voltages on a dual-voltage motor.

• Describe the operation of the current and potential relays used for starting single-phase hermetic compressor motors.

Compressor Control and Protection

• Name the two basic categories of motor-starting devices and tell how each operates.
• Explain the function of a reduced-voltage starter and name the five kinds used with compressor motors.
• Describe the three kinds of motor overload protection commonly used with compressor motors.
• Discuss the causes of, effects of, and solutions for high discharge pressure, low suction pressure, and low oil pressure.
• Explain the function of a suction-line accumulator.
• Explain why crankcase heaters are sometimes necessary.

• Explain how heat exchangers improve the performance of a compressor

 Compressor Maint, Troubleshooting, & Repair

• State the first rule of preventive maintenance for compressors and related components.

• List preventive maintenance procedures common to most compressors.

• Explain how to calculate voltage imbalance in a three-phase motor.

• Name at least three possible causes of a low compressor oil level.

• Name at least three possible causes of compressor overheating.

• Explain how electrical problems can cause various system malfunctions

• Explain how to pump down a compressor for repairs.

• Describe compressor disassembly, cleaning, inspection, and reassembly procedures.

• Describe motor spot burnouts and cookouts, list their possible causes, and explain how to determ