Assignment - Compressor #1 Flashcards
Name two types of positive displacement compressors.
- Reciprocating
- Rotary
How can you increase the pressure in a compressor arrangement?
- increase pressure by reducing volume
- heating the gas to increase molecule speed
- increasing the number of stages i.e.: 2 stage
What opens and closes the reciprocating compressor valves?
Difference in pressure. Pressure flows from high to low.
What is the difference between a single and double acting compressor?
Single acting compressors compress gas on one side of the piston, and double acting compressors compress gas on both sides of the piston.
What is the function of the crosshead and guides?
The purpose of the crosshead and guides is to keep the piston rod centred through the packing to minimize leakage from the compression cylinder.
What is the minimum # of cylinders to make it multi staged?
2
Can you have multi cylinders on a single stage compressor? and if so what is it for?
Yes - to increase volume
What is the purpose of an intercooler?
Intercoolers cool the air between stages. Cooler air is more dense. Intercoolers = increased efficiency
A double acting compressor will generate how many compression strokes per revolution of the crank shaft?
2 = 1 per stage
What are the affects of high altitude on a compressor?
The air is less dense, compressor will work longer to come up to pressure. Less efficient.
2 of the main types of reciprocating compressor unloaders are?
- pressure switch
- inlet valve unloader
Cooler air makes the compressor?
More efficient
After coolers are used for?
The purpose of an after cooler is to remove moisture after compression is complete.
What are 3 things that a receiver must have?
- pressure gauge
- relief valve
- drain valve
In a compressor system, the pressure relief valve can be set no higher than?
The minimum safe working pressure. Pressure relief is set to the weakest link in the system.
Define “Clearance Volume”
Clearance volume refers to the space between the piston and the cylinder head when the piston is at TDC.
Define “Clearance Pockets”
A clearance pocket increases the clearance volume to reduce compressor efficiency.
Define “Rod Loading”
Rod loading refers to the sums of the suction and discharge pressures acting on both sides of a double acting compressor piston.
Why is rod reversal necessary?
Rod reversal is necessary in order to allow oil to flood around the crosshead pin and connecting rod pin bushings and to a lesser extent, the crosshead guides and connecting rod crankshaft bearings.
Before working on a compressor, you must do this in the proper order.
Isolate
Purge
Vent
Lock out
What are the 2 ways the piston is retained on the rod?
The piston is locked onto the rod against a shoulder or on a taper with a locknut.
What are 2 types of flow?
- Laminar
- Turbulent
One of the functions of a receiver is?
Air receivers are used to store compressed air to take up fluctuations in demand and allow the system pressure to vary within reasonable limits.
