Compressors Flashcards
0
Q
What is atmospheric pressure at sea level?
A
1.01 bar, 14.7 psi, 101.4 3K PA
1
Q
What is difference between PSIG and PSIA
A
PSIG-psi gauge
PSIA-psi absolute or PSI atmosphere
At zero PSIG there is 14.7 PSIA
2
Q
When temperature is increased in an enclosed space, the temperature does what?
A
The temperature increases
3
Q
If the flow rate is constant, and the velocity is decreased, there will be an increase or decrease in pressure?
A
Increase in pressure
4
Q
Is a compressor more or less efficient at higher altitudes
A
Less efficient
5
Q
What is the name of the compressor that has power pistons and compression pistons sharing the same crankshaft?
A
An integral compressor
6
Q
What are three common devices for measuring pressure?
A
Barometer, manometer, bourdon tube
7
Q
What is the purpose of the crosshead and guides?
A
To keep the piston rod centered through the packing to minimize leakage from the compression cylinder
8
Q
How is the piston locked onto the rod?
A
It is locked on a shoulder and nut or on a taper with a locknut
9
Q
In an integral compressor what is the name of the rod connecting from the crankshaft?
A
Master connecting rod
10
Q
What is a distance piece?
A
It houses the crosshead and cross head guides and oil wipers
11
Q
What are the two types of airflow?
A
Laminar and turbulent flow
12
Q
What is the purpose of an intercooler?
A
It increases efficiency. A bonus is it also draws out some moisture
13
Q
What is the purpose of an aftercooler?
A
To remove moisture
14
Q
What are three things that all pressure vessels must have?
A
Gauge , drain, and safety relief valve
15
Q
A safety valve should be set at what pressure in the system?
A
It should be set no higher than the lowest maximum pressure rating of any part in the system
16
Q
What is the purpose of a multistage compressor?
A
To achieve higher pressures
17
Q
What causes reciprocating compressor valves to open?
A
The pressure differential
18
Q
Name two types of positive displacement compressors
A
Reciprocating and rotary compressors
19
Q
How can you increase the pressure in a compressor arrangement
A
Increase the temperature, decreased container size, put more volume in it, Stage it,
20
Q
What opens and closes the reciprocating compressor valves?
A
Air pressure differential
21
Q
What is the difference between a single and double acting compressor?
A
A single acting compressor creates pressure on one side of the piston and the double-acting creates pressure on both sides
22
Q
What is the function of the crosshead and guides?
A
To keep the piston rod centered through the packing to minimize leakage from the compression cylinder
23
Q
What is the minimum number of cylinders to make it multistaged?
A
Two
24
Can you have multiple cylinders on a single stage compressor if so what is it for?
Yes you can have multiple Saunders all single stage it is used for larger volume of compressed air or gas
25
What is the main purpose of the intercooler?
To cool the air between stages of compression and increase efficiency
26
A double acting compressor will generate how many compressions strokes per revolution of the crankshaft?
Two
27
What are the effects of high altitude on a compressor?
The higher altitude has less atmospheric pressure so the compressor is less efficient.
28
What are the two main types of reciprocating compressor unloaders?
Inlet valve unloader, pressure switch unloader, bypass unloader
29
Cooler air makes the compressor?
Decreases the amount of power required to compress a gas so it is more efficient
30
After coolers are used for what?
To remove moisture after compression is complete
31
What are three things every air receiver must have?
Gauge, drain, safety relief valve
32
Any compressor system, the pressure relief valve can be set no higher than what?
It must be set no higher than the lowest maximum pressure rating of any part in the system
33
Define clearance volume?
Clearance volume is the space between the piston in the cylinder head when the piston is at top dead center
34
Define clearence pockets?
Clearance pockets increase the clearance volume to reduce compressor efficiency
35
Define Rod loading
Rod loading refers to the sum of the suction and discharge pressures acting on both sides of a double acting compressor piston
36
Why is Rod reversal necessary?
In order to allow oil to flood around around the crosshead pin and connecting rod pin bushings
37
Before starting work on a compressor what must you do?
It was purge the compressor that invented. it must run to purge it.
38
What are the two ways a piston is retained on the rod?
It is locked against the shoulder with a nut, or on a taper with a locknut.
39
What are the two types of air flow?
Laminar flow, turbulent flow
40
What is the purpose of the receiver?
It is used to store the compressed air and to take up fluctuations in demand and allow the system pressure to very within reasonable limits
41
What are the four components to be compressor valve?
Seat,sealing elements,guard, and assembly elements
42
Valve lift refers to what?
How far the lift is away from the ceiling element
43
Too much of valve lift causes what?
Valve flutter or multiple impacting
44
What are three advantages of synthetic ceiling elements?
Lighter weight, reduced noise level, limited damage to other compressor components in the event of failure.
45
What are the added advantages of v shaped sealing elements
Better airflow, reduced turbulence
46
Which valve has the least restriction of flow?
Concentric ring
47
Of the two valves intake and exhaust which one generally needs to be replaced more often?
Exhaust
48
What Applications are dampened disk valves suitable for?
High-speed applications
49
When are poppet valves a good choice?
They are well-suited to applications where there is condensate or other liquids in the gas stream
50
What is a good practice when one spring any set shows wear?
The entire set should be replaced
51
What are the three measurements on the channel valve?
Left check, side clearance, and end clearance
52
What is a common we in the field to check valve sealing?
A leak test fill the seat parts of the valve with the fluid and observe the leakage rate for a set period of time
53
Pertaining to valves, what is one cause excessive Rod load?
Installing a discharge valve backwards or mixing up the suction and discharge valves will cause excessive rod loading
54
What is atmospheric pressure at sea level?
14.7 PSIA
55
What is the definition of a vacuum?
Vacuum occurs when the pressure in a building or container is less than the pressure surrounding it which is normally atmospheric pressure
56
What are three common devices for measuring pressure?
Barometer, manometer, boardon tube
57
Define pascals law
It states that pressure applied to a confined or static fluid is transmitted equally in all directions while being transmitted at right angles to the surface
58
Define Bernoullis principal
It states that if the velocity of a fluid increases the pressure decreases the same happens in reverse
59
What is special about a labyrinth compressor
It has a special design that allows it to run without oil
60
Name to compressor types that run without oil
Labyrinth compressor and diaphragm compressor
61
What is an integral compressor?
It is an engine and compressor combined into one frame and one common crankshaft
62
How frequently are compressor booster stations needed in kilometers?
Every 150-300 km along the pipeline
63
When pressure is increased in an enclosed space, what happens to the temperature?
It increases
64
What is the purpose of the crosshead and guides?
To keep the piston rod cantered through the packing to minimize leakage from the compression cylinder
65
How is the piston connected to the rod?
It is locked against a shoulder, or on a taper with a locknut.
66
What is the distance piece?
It fits between the cylinder and main frame to prevent contamination between the cylinder gasses and oil from the crankcase. It houses the crosshead, guides and oil wipers
67
What are some examples of unloaders?
Start/stop, inlet valve unloaders, bypass, variable volume pocket
68
What is the purpose of an intercooler?
It cools the gas, to increase efficiency. The bonus is that it draws out some moisture.
69
What is the purpose of an aftercooler?
To remove moisture
70
What are three types of air dryers?
Desiccant type, deliquescent dryer, and refrigeration type
71
What must all pressure vessels have?
Gauge, drain, and safety relief valve
72
What is the setting on a safety relief valve?
It must be set no higher than the lowest maximum pressure rating of any part of the system
73
What must you do if a higher than 5:1 compression ratio is needed?
It must be staged
74
Define swept volume
Refers to the volume of air that is swept or pushed out of the cylinder on the compression stroke
75
Define clearance volume
The space between the piston and cylinder head when piston is at TDC
76
Why is rod reversal necessary?
To allow oil to flood around the crosshead pin and connecting rod pin
77
What are the four components of a valve?
Sealing element, valve seat, valve guard, assembly elements
78
What is the best flowing valve?
Concentric ring valve
79
Which valve is good for high speed applications?
Dampened disc
80
Which valve is well suited for air streams with moisture in it?
Poppet valve
81
Explain the leak test on valves
Fill the seat ports of the valve with a fluid and observe the leakage rate over a set period of time
82
When one spring shows signs of wear, what should be done?
The whole set should be replaced.
83
What would be a consequence of mixing up suction and discharge valves?
It would cause excessive Rod loading
84
What is a common type of piston?
Trunk style (single acting only)
85
Is the ring land diameter smaller or larger than the skirt?
Smaller
86
What is a full floating piston pin?
They are free to move inside the con Rod bushing and piston bushing. They are held in with snap rings and are the most common.
87
What is a semi floating pin?
It is locked into either the con Rod, or the piston and rotate on the other
88
Define Rod runout
It means that the Rod is not running totally straight through the packing
89
What are some causes of Rod runout
Worn piston rings, crosshead misaligned, crosshead guides worn, improper preload, setscrew on jamnut incorrect
90
What are some common materials for piston rings.
Cast iron, lead bronze, tin bronze, and synthetics (Bakelite, or Teflon)
91
Name three types of piston ring joints
Butt joint, angle joint, and step joint (for higher pressure applications)
92
What is the purpose of a rider band?
To prevent the piston from touching the cylinder and to support the weight of the piston and half the piston Rod
93
Which rider ring is used if it passes over a valve port?
The uncut rider ring
94
What is the most common system of cooling in industrial compressors?
Circulated liquid cooling
95
What must be the temperature of the cooling liquid at the cylinder be, and why?
It should be set approx 5.5 degrees warmer than the incoming gas, so it doesn't cause condensation inside the cylinder
96
Name the types of cylinders
Cast integral, wet liners, dry liners
97
Give the procedure for checking for cylinder wear
Check it inline with crankshaft, and at 90 degrees in several locations
98
What pressure are cylinders hydro tested to?
1.5 times their maximum allowable working pressure
99
What should be done to a cylinder that has been honed or deglazed?
Should be washed with hot soapy water.
100
Name the four types of packing rings
Pressure breaker, radial cut, tangent cut, backup ring
101
Which ring does the most sealing
Tangent cut ring
102
Which is the only ring used singly?
The pressure breaker ring
103
What ring combination is used on a double acting cylinder
Two tangent cut rings dowels together
104
In lubricated packing where is the oil distributed?
It enters through the flange at the top and is directed near the pressure side, but not all the way to pressure breaker
105
Where is liquid cooled packing entering ?
It enters at the bottom so that no air can get trapped
106
Where is the oil wiper packing found?
On the crank side of the distance piece
107
What is proper ratio when setting clearance in piston and cylinder head?
2/3 head end, 1/3 crank end. This allows for expansion from heat.
108
What is the purpose of the distance piece
It allows access to the oil wipers
109
What is the purpose for multiple compartment distance pieces?
In applications where a complete sealing of an explosive gas from the compression chamber must exist
110
What are some ways to balance an opposing throw compressor?
Use a balance nut, or different metals in the Pistons. A larger piston made of aluminum will weigh same as a smaller one of steel
111
What are the two types of connecting rods?
Straight cut, and bias cut. Bias is less common and you use them when you must pull the connecting rod out through the cylinder bore
112
What are the four main jobs of lubrication?
Lubricating, cooling, ceiling, prevent corrosion, reduces wear
113
What type of lubrication system is commonly found on small compressors?
Splash lubrication system
114
Name some causes of low oil pressure
Increased clearance in bearings, air enters the oil lines, plugged oil filter
115
What are the two common systems for supplying metered amounts of oil?
Pumped a point system, and divider block or divider valves
116
Which system allows for individual adjustment to each point?
Pump to point
117
What is the operating pressure of the divider system above the last stage cylinder pressure?
10% higher
118
What must be done after servicing the divider lubrication system?
You must bleed the air out of the lines after servicing
119
Paper element filters down to what?
3-5 microns
120
Before locking out a compressor what two things must be done?
It must be purged first with an inert gas and then vented
121
After any kind of worker service on the compressor it's always a must to do this before you start it again?
Bar the compressor over one complete revolution two is preferred
122
Where would you find an articulating rod?
In an integral type compressor
123
When torquing Bolts on rods what is the minimum number of steps used?
Must be done in a minimum of three stages
124
What is a bump check used for?
A method to determine whether a bearing is worn enough to warrant further dismantling
125
When sizing a compressor foundation what are the four things to take into consideration?
The size, weight, vibration characteristics, and the type of driver
126
What is a wire alignment used for checking?
Bearing location measurements
127
When referencing bouncing as a rule the greater number of compressing cylinders the?
Fewer the number of vibrational forces will occur
128
When performing a crank deflection test in the dial has a reading of five mills what might be the cause?
Soft foot, bent crankshaft, improper installation of compressor
129
Why do we need bearing spread?
We need it for location and to keep in place during installation
130
Bearing crush is used to?
It is used for good seating and good heat transfer
131
What are dowels and locking tabs used for?
Anti-rotation device
132
Why do we have clearance pockets on the compressor and where are they located?
They are used to provide a means of controlling the output to meet the demand and are located at the head and
133
What is the primary reason for keeping rod run out within limits?
To limit wear and increase sealing
134
Which ring is used by itself and where is it located?
The pressure breaker ring. It is located closest to the cylinder or pressure end
135
In a two ring set which ring faces the pressure?
Radial ring
136
Dots or letters on the rings face towards or away from the pressure?
Towards the pressure
137
What are liquid cooled packing case is normally used for?
Oil free applications
138
What happens if the surface of the piston rod is scratched or damaged?
It will ruin the seal of the packing
139
We inspect and measure cylinders to see if they are?
Straight, round, and within specified dimensions
140
What is the purpose of the connecting rod?
To convert rotating motion to reciprocating motion
141
Where are cracks likely to be located on the crank?
The corner of the fillets, and around oil holes
142
How does a dynamic system make pressure?
It restricts flow to get pressure
143
When does valve flutter or multiple impacting occur and what do you do to correct it?
It occurs at high speeds and is fixed by using a dampening desk
144
What should be done to the valve chair bolt when removing the valve?
The valve chair boat should always be backed off before removing the valve cover
145
Is compressor rotation the daily check?
No. It is only done on installation or when a major service is done
146
What are some examples of daily checks?
Oil levels , fluid levels , water temperature
147
What is the purpose of the preload?
It is used to compensate for thermal expansion so the rod runs true when at operating temperature
