Compressors Flashcards
What is the biggest concern with compressors?
Moisture
What is the most important thing on a Compressor / pneumatic system?
Volume of air
How are compressors classified??
Principle operations
Their motion
What is maximum pressure control.?
It prevents further compression one the required maximum is reached
What is an unloading device?
’ It consist of a set of fingers controlled by a pilot line from the systems air pressure
What are other methods to controlling the maximum air pressure of the Compressor?
Throttling the air intake
Using an variable speed drive
Using an pressure switch
Where would axial compressors be used?
Gas turbines
What are some benefits of an axial compressor?
High efficiency
Large Mass of flow capacity
What are 2 disadvantages of axial compressors?
Large pressure rising make them complex
Expensive
What is the purpose of a diahgram in a compressor ?
Prevent short cycling of air
Stop air from leaking from one side to the other
What are a few things lubricants must have (4)?
Excellent protection from rust and corrosion
Good demulsibility to shed water that enters the lube system
Prevention of acidity, sludge, deposit formation
Good foam control
What does BDC stand for?
Bottom dead centre
What style of piston rings ave found in both single-acting and double acting compressors?
Compressor rings
What are the three measurements that must be made on an overhauled channel value?
End clearance
Side clearance
Lift
What value is best suited for high speed services?
A. Feather
B. Channel value
C. Dampenend disc value
D. Concentric Ring value
C. Dampenend disc valve
Why is it a mistake to clean the value before inspecting it?
Because you can erase valuable clues such as leaks, and foreign parts
Why should you rotate the compressor at least once prior to starting up?
Ensuring nothing is hitting, binding or rubbing
A pressure differential causes this component to open/ close?
Valves
What is the primary function of the distance piece?
Prevent contamination between the cylinder gases and the oil from the crankcase
What Motion does a crankshaft convert of the prime mover? What then does a prime mover convent to?
Rotary
Reciprocating
Where are intercoolers located?
Between stages
Where are aftercoolers located?
After final stage of compression
When are reciprocating compressors used?
When High Compression ratios are required per stage with high flow rates and where process fluid is relatively dry
What are the two classifications of industrial compresses
Intermittent (Pd)
continuous flow( c )
What is a stator?
Comprised of a series of blades attacked to the casing walls
What is the purpose of a shroud?
Provide support for the longer stator vanes at the inlet to provide a gas seal between the rotating and stationary.
What does VVCP stand for?
Variable volume clearance pocket
When measuring a cylinder bore to check for wear , it is important to measure in the area of?
Ring travel
Compared to a dry liner, a wet liner would have thicker or thinner wall thickness?
Thicker
What is the function of Rod packing?
To prevent leakage from the cylinder along the piston Rod.
What type of cut does a pressure breaker have?
Radial cut
The Dots on piston rings, do they go up or down? (Block test)
They go up
How could you make an Compressor more efficient?
Preheating air
Why is a jog or bump test performed on a compressor?
To check rotation
What will happen is a servo value is stuck in the closed position?
The unloader value never gets an oil signal to tell it to close so the Compressor is always trying to supply the full volume of air
How is the operation of the control system set at any specific pressure?
Spring setting on the servo valve
What component contains the inlet/outlet ports in a wet sliding vane compressor?
Stator
Where is the servo valve located in a sliding vane compressor?
Oil reservoir
Where is the unloader valve located?
After inlet hose but before the rotor
Which valve May be used to unload the compressor for ease of starting?
Safety relief valve
What does it mean for a compressor to have a built -in pressure ratio?
That its not adjustable
What is the only major moving part in a sliding vane compressor?
Rotor assembly
What are the two main categories of screw compressors
Wet screw
Dry screw
Which rotor is the driver on a screw compressed
Male rotor
What 4 things determine the capacity of a screw compressor?
Rotor length
Diameter
Lobe (flute) design
Speed
What determines the discharge pressure of a screw compressor?
Length of the compression path along the lobes and flutes but for most part determine by the location of the inlet and/or discharge ports
Which component does the air enter after leaving the oil-flooded Compressor?
Separator
Which valve operates like the thermostat in a motor vehicle ?
Thermal mixing valve
What is a screw compressors simplest type of control system?
Online/offline
What does VFD stand for?
Variable frequency drive
When being proper maintained , how many hours in between majoroverhauls can the Compressor experience?
80,000 to 100,000 hrs
What could result in a compressor when there is a stuck blowdown valve?
Low air delivery
What is the most common cause of high discharge air temperature in a liquid cooled compressor?
A restriction of flow of the cooling air through the radiator
What is pressure ratio (PR)?
Is the ratio of the absolute Compressor incoming air pressure to the absolute compressor discharge pressure.
What does A pressure valve do?
Keeps air from back flowing
Males sure all systems are running before adding pressure
At what pressure with the valve stay open? (Sliding vane compressor)?
60Psi
What does aux mean?
Nice to have
What does Ann mean?
Must have
What do oil return valves do?
Prevents hydraulic locking
Prevent pump from being over pressurized
What is another name for vacuum pump ?
Negative pressure (below 14.7)
What does A vacuum relief valve do?
Prevent a vacuum buildup within the rotor area and to prevent the vanes to become unstable and chatter or bounce around
How do lobe/roots blowers move air?
One moved an fixed volume of air from one side of the blower to the other as the lobes rotate
When are timing gears used?
Dry applications
Why use three lobe blowers? (4)
Increase efficient
Less slip
Less noise
less leakage
What is an unloading device?
Allows the drive to run with the least hp demand when it reaches maximum fair pressure
What does adiabatic mean?
An process or condition where Heat dosent leave or enter a system
What does ISOthermal mean?
Involving or containing a constant temperature
What is the purpose of an diagram in a compressor?
Prevent short cycling
Stop air from leaking from one side to the other
