Compressor Flashcards
What are the 2 types of compressors?
Positive displacement
Dynamic
What are the 2 types of reciprocating compressors?
Piston and diaphragm
What are the 2 types of rotary compressors?
Sliding vane
Screw
What are the 2 types of dynamic compressors?
Centrifugal and axial
How does a reciprocating compressor work?
- Volume increases in the cylinder
- This pressure difference causes a valve to open
- Air enters the cylinder while closing the outlet valve
- As the piston is forced up, the volume of air in the cylinder is reduced -compression
- inlet closes and outlet opens allowing compressed air to be released
How does a simple spring valve work?
It’s a non return valve and the pressure acts on a spring which allows it to open and air to enter
How does a Reed valve work?
It’s a one direction/ non return valve which opens and closes due to changing pressure across both sides
How does a double acting compressor work?
Produce a more even supply of air than a single, uses two sets of valves
What is a cross head?
Keeps the piston rod perpendicular
What are the advantages of a multi stage compressor?
Efficiency
Less heat
Less wear on parts
How does a diaphragm compressor work?
Piston is separated from the suction chamber but still moves in a reciprocating motion
This prevents the air becoming contaminated with oil and other dirt
Why is oil injected into the rotary vane compressor?
Cool the air
Lubricate the air
Provide a seal between the vanes and stator walls
How does the rotary vane compressor work?
Air is drawn in from the atmosphere and trapped between the rotating vanes
Vanes are then pushed in and the volume reduces increasing the pressure
Highest pressure of air is released to the compressor outlet
How does a screw compressor operate?
As rotary revolve, air is drawn into the large volumes which is then forced through rotors where the volume gets smaller and the air is compressed
What is the screw compressor available in?
Oil flooded or dry versions
What is the purpose of an oil bridges in a rotor?
Provide a seal and assist in transferring mechanical energy
How does a dynamic compressor work?
Air is drawn into the compressor abs takes place due to acceleration, pressure is increased by kinetic energy
How does a centrifugal compressor work?
Air is trapped between blades and is then accelerated, this throws air outwards leaving the blade tips with increased Velocity and pressure
Then enters a diffuser and collecter where air becomes a higher pressure
How does an axial compressor work?
Utilises centrifugal force to compress atmospheric air which is moved axially , compression takes place as volume gets smaller
