Assignment - Compressor #1

Question 1

Name two types of positive displacement compressors.

Answer 1

• Reciprocating

- Rotary

Question 2

How can you increase the pressure in a compressor arrangement?

Answer 2

• increase pressure by reducing volume
• heating the gas to increase molecule speed
• increasing the number of stages i.e.: 2 stage

Question 3

What opens and closes the reciprocating compressor valves?

Answer 3

Difference in pressure. Pressure flows from high to low.

Question 4

What is the difference between a single and double acting compressor?

Answer 4

Single acting compressors compress gas on one side of the piston, and double acting compressors compress gas on both sides of the piston.

Question 5

What is the function of the crosshead and guides?

Answer 5

The purpose of the crosshead and guides is to keep the piston rod centred through the packing to minimize leakage from the compression cylinder.

Question 6

What is the minimum # of cylinders to make it multi staged?

Answer 6

2

Question 7

Can you have multi cylinders on a single stage compressor? and if so what is it for?

Answer 7

Yes - to increase volume

Question 8

What is the purpose of an intercooler?

Answer 8

Intercoolers cool the air between stages. Cooler air is more dense. Intercoolers = increased efficiency

Question 9

A double acting compressor will generate how many compression strokes per revolution of the crank shaft?

Answer 9

2 = 1 per stage

Question 10

What are the affects of high altitude on a compressor?

Answer 10

The air is less dense, compressor will work longer to come up to pressure. Less efficient.

Question 11

2 of the main types of reciprocating compressor unloaders are?

Answer 11

• pressure switch

- inlet valve unloader

Question 12

Cooler air makes the compressor?

Answer 12

More efficient

Question 13

After coolers are used for?

Answer 13

The purpose of an after cooler is to remove moisture after compression is complete.

Question 14

What are 3 things that a receiver must have?

Answer 14

• pressure gauge
• relief valve
• drain valve

Question 15

In a compressor system, the pressure relief valve can be set no higher than?

Answer 15

The minimum safe working pressure. Pressure relief is set to the weakest link in the system.

Question 16

Define “Clearance Volume”

Answer 16

Clearance volume refers to the space between the piston and the cylinder head when the piston is at TDC.

Question 17

Define “Clearance Pockets”

Answer 17

A clearance pocket increases the clearance volume to reduce compressor efficiency.

Question 18

Define “Rod Loading”

Answer 18

Rod loading refers to the sums of the suction and discharge pressures acting on both sides of a double acting compressor piston.

Question 19

Why is rod reversal necessary?

Answer 19

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.

Question 20

Before working on a compressor, you must do this in the proper order.

Answer 20

Isolate
Purge
Vent
Lock out

Question 21

What are the 2 ways the piston is retained on the rod?

Answer 21

The piston is locked onto the rod against a shoulder or on a taper with a locknut.

Question 22

What are 2 types of flow?

Answer 22

• Laminar

- Turbulent

Question 23

One of the functions of a receiver is?

Answer 23

Air receivers are used to store compressed air to take up fluctuations in demand and allow the system pressure to vary within reasonable limits.