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Millwright 2nd Year 2018 > Reciprocating Compressors and Valves > Flashcards

Reciprocating Compressors and Valves Flashcards

1
Q

When volume of a gas is reduced?

A

The gas increases in temperature and pressure

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2
Q

What is the purpose of “purging” a compressor?

A

To remove dangerous gases prior to disassembly

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3
Q

What is the purpose of an aftercooler?

A

To remove moisture after compression

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4
Q

What must be used to prevent explosive pressures from forming in the event of a blockage in compressed gas piping or vessels?

A

Pressure Relief Valves

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5
Q

What are the 3 ways that the pressure of a gas can be increased?

A

Decrease volume, increase temperature and pack more into a confined space

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6
Q

What will happen if gas is heated in a confined space?

A

It will increase in pressure

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7
Q

What would be used to improved the efficiency of a multi-stage compressor?

A

add or use an intercooler

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8
Q

Why is it important to make piping connections to the top of a main supply header?

A

This prevents water and solids contaminants from reaching equipment

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9
Q

Pressure applied to a confined fluid is transmitted equally in all directions and at right angles to the surface, this is known as?

A

Pascal Law

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10
Q

If the temperature remains constant, the volume changes inversely to the pressure, this is known as?

A

Boyle’s Law

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11
Q

It is stated that if the pressure on a given volume of a gas is held constant, the volume changes in direction proportions to the absolute temperature, this is known as?

A

Charle’s Law

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12
Q

If the flow rate is constant, the sum of the kinetic and the potential energy at various points in the system is constant, fluid increases, the pressure decreases?

A

Bernoulli’s Principle

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13
Q

What is the Combined Gas Laws?

A

combination laws of Boyle, Charle and Gay-Lussac’s law

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14
Q

What are the name of the positive displacement reciprocating compressors?

A
  • Single acting
  • Double acting
  • Labyrinth
  • Diaphragm
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15
Q

List all the positive displacement rotary/screw compressors?

A
  • Sliding vane
  • Liquid Ring
  • Single Rotor
  • Two Rotor
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16
Q

List some problems moisture has on a compressor or compressed air system?

A
  • causes rust
  • harmful to lubricants
  • form sludge
  • In some cases moisture might freeze
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17
Q

What happens when the bourdon tube gauge pressure goes up?

A

The tube straighten out

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18
Q

What is a single-acting compressor?

A

Compression happens on one side of the piston.

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19
Q

What is a double-acting compressor?

A

Compresses gases on both sides of the piston

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20
Q

Which compressors are the most common used because of the widest range of operating suction and discharge pressure?

A

Reciprocating Compressors

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21
Q

The term single-acting means what?

A

Compression on one side of the piston

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22
Q

Can the labyrinth compressor run without oil?

A

yes, by creating a seal between the cylinder in the piston with a series of grooves machined on the piston and cylinder wall

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23
Q

An integral compressor is what essentially when combined into one frame with one common crankshaft?

A

An Engine and a compressor combined

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24
Q

What does the Conrod connect to on a diaphragm compressor?

A

Flexible membrane or a diaphragm

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25
Q

Where is a gas injection compressor most common?

A

Oil production

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26
Q

What are 3 ways pressure can be increased?

A
  • Heat it
  • Reduce the volume
  • Add more gas into a confined space
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27
Q

What compressors has a sealed container where pressure is created on the inside surfaces by molecules of gas striking the surface creating a force?

A

Positive Displacement Compressors

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28
Q

How is gas lifts different than gas injection?

A

Gas passes through a series of lift valves pushing the oil out of the well.

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29
Q

How many compressors are used for gas gathering?

A

One central compressor to pull gas from a series of locations into one central pipeline

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30
Q

How many kilometers should a boast station be from one another?

A

150 - 300 km along pipeline

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31
Q

What kind of compressors used more commonly in the compressor lift station application?

A

Centrifuge Compressors

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32
Q

Bernoullis principal and the law of conservation of energy apply to what?

A

All Fluids

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33
Q

Define clearance volume?

A

Clearance Volume is the space between the piston in the cylinder head when the piston is at top dead center (TDC)

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34
Q

What is the purpose of inter cooler?

A

To increase efficiency and to draw moisture out

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35
Q

What is the purpose of a receiver?

A

To store the compressed air and to take up fluctuations in demand and the system pressure to very within reasonable limits

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36
Q

What is the definition of vacuum?

A

is when the pressure in a building or container is less than the pressure surrounding it which is normally atmospheric pressure

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37
Q

What is special about a labyrinth compressor?

A

It has a special design that allows it to run without oit

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38
Q

What are the compressors type that can run without oil?

A
  • Labyrinth Compressors

* Diaphragm Compressors

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39
Q

What are the two types of air flows?

A
  • Laminar Flow

* Turbulent Flow

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40
Q

How is the piston connected to the rod?

A

It is locked against a shoulder or on a taper with a locknut

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41
Q

What is the distance piece?

A

It houses the crosshead, guides and oil wipers

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42
Q

What are some examples of unloaders?

A
  • Pressure switch unloader
  • Start/Stop
  • Inlet Valve Unloader
  • By Pass
  • Variable Volume Pocket
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43
Q

What are the 3 main types of reciprocating compressor unloaders?

A
  • Inlet Valve Unloader
  • Pressure Switch Unloader
  • Bypass Unloader
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44
Q

What are the 3 types of air dryers?

A
  • Desiccant type
  • Deliquescent type
  • Refrigeration type
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45
Q

What is the setting on a safety relief valve?

A

The maximum/highest of the lowest pressure rating of any part of the system

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46
Q

What must you do if a higher than 5:1 compression ratio is needed?

A

It must be staged

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47
Q

Out of the two valves, intake and exhaust, Which one generally needs to be replaced more often?

A

Exhaust @ discharge

48
Q

Dampened disc valves are suitable for _______ applications

A

High Speeds

49
Q

What are poppet valves a good choice for?

A

Well suited to applications where there is condensate or other liquids in the gas stream

50
Q

Three (3) advantages to synthetic sealing elements?

A
  • Lighter weight
  • Limited damage to other compressor components in the event of breakage
  • Reduce noise
51
Q

Four (4) components of a compressor valve are?

A
  • Seat
  • Guard
  • Sealing elements
  • Assembly elements
52
Q

Added advantages of a V shape sealing element?

A
  • Better Flow
  • Smoother flow path
  • Less turbulence, does not get dirty
53
Q

Which valve has the least restriction to flow?

A

The Ring Valve

54
Q

What is good practice when one spring in a set shows wear?

A

Replace the Set

55
Q

Three (3) measurements on a channel valve?

A
  • Lift Check
  • Side Clearance
  • End Clearance
56
Q

What is a common way in the field to check if a valve is sealing?

A

Leak test with window washer fluid

57
Q

Define Swept volume?

A

It refers to the volume of air that is swept or pushed out of the cylinder on the compression stroke

58
Q

Why is rod reversal necessary?

A

To allow oil to flood around the crosshead pin and connecting rod bushing

59
Q

What is the best flowing valve?

A

Concentric Ring Valve

60
Q

What is a common type of piston?

A

Trunk Style (Single acting only)
or
Trunkatted

61
Q

Is the ring land diameter smaller or larger than the skirt?

A

Smaller

62
Q

Valve lift refers to what?

A

How far the lift is away from the ceiling element

63
Q

What pressure are cylinders hydro tested to?

A

1.5 times their maximum allowable working pressure

64
Q

Which rider ring is used if it passes over a valve port?

A

The Uncut Rider Ring

65
Q

What should be done to a cylinder that has been honed or deglazed?

A

Should be washed with soapy water

66
Q

Name the type of Cylinders;

A
  • Cast Integral
  • Wet Liners
  • Dry Liners
67
Q

Name four (4) types of Packing Rings;

A
  • Pressure Breaker
  • Radial Cut
  • Tangental Cut
  • Back-Up Ring
68
Q

Which Ring does the most sealing?

A

Tangental Cut

69
Q

Which ring is the only one used singly?

A

Pressure Breaker Ring

70
Q

What ring combination is used on a double acting cylinder?

A

Two Tangental Cut Rings dowels together

71
Q

In lubricated packing where is the oil distributed?

A

It enters through the flange at the top and isdirected near the pressure side, but not all the way to the pressure breaker

72
Q

Where does liquid coolant enters to cooled the packing?

A

at the bottom, so no air can get trapped

73
Q

Where is the oil wiper packing found?

A

on the Crank side of the distance piece

74
Q

What is proper ratio when setting clearance in piston and cylinder head?

A

2/3 on head end
1/3 on Crank end
*This allows for expansion from heat

75
Q

What is the purpose of the distance piece?

A

It allows access to the oil wipers

76
Q

What is the purpose for multiple compartment distance pieces?

A

In applications where a complete sealing of an explosive gas from the compression chamber must exist

77
Q

What are some ways to balance an opposing throw compressor?

A

use different metal pistons, balance nut, larger piston made of aluminum

78
Q

What is the most common system of cooling in industrial compressor?

A

Circulated liquid cooling

79
Q

What are the two (2) styles of connecting rods?

A
  • Bias

* Straight Cut

80
Q

What are the four (4) main jobs of lubricants?

A
  • Prevent corrosion
  • Reduce Wear
  • Cooling or Carry away heat
  • Sealling
81
Q

What type of lubrication system is commonly found on small compressors?

A

Splash lubrication system

82
Q

What must be the temperature of the cooling liquid at the cylinder be, and why?

A

5.5° degrees more warmer than the gas, so it doesn’t condensate inside the cylinder

83
Q

Name some causes of low oil pressure?

A

Increased clearance in bearings, air enters the oil lines, plugged oil filter, (Crankshaft main bearing)

84
Q

What are the two (2) common systems for supplying metered amounts of oil?

A

Pump to a point to point system
and
Divider block valves

85
Q

Which system allows for individual adjustment to each point?

A

Pump to a point to point system

86
Q

what is the operating pressure of the divider system above the last stage cylinder pressure?

A

10% or higher

87
Q

What must be done after servicing the divider lubrication system?

A

You must bleed the air out of the lines after servicing

88
Q

Paper element filters down to what microns?

A

3 - 5 microns

89
Q

Before locking out a compressor what two things must be done?

A
  • Purged first with inert gas or sweet gas

* then Vented

90
Q

After any kind of work or service on the compressor is done, what must always be done before starting up again?

A

Bar the compressor over on complete revolution.

Two is better but one is a must

91
Q

When would you find an articulating rod?

A

In an Integral type compressor

92
Q

When torqueing bolts on rods what is the minimum numbers of steps used?

A

3 steps or 3 stages

93
Q

What is a bump check used for?

A

A method to determine whether a bearing is worn enough to warrant further dismantling of main bearings

94
Q

When sizing a compressor foundation what are the four (4) things to take into consideration?

A

*The Size
*Weight
*Vibration characteristics
The type of Driver

95
Q

What is a wire alignment used for checking?

A

Bearing location measurement

96
Q

What are the three (3) things every air receiver must have?

A
  • Gauge
  • Drain
  • Safety Relief Valve
97
Q

When referencing bouncing as a rule the greater number of compressing cylinders the?

A

Fewer the number of vibrational forces will occur

98
Q

When performing a crank deflection test in the dial has reading of five mills, what might be the cause?

A
  • Soft Foot
  • Bent Crankshaft
  • Improper installation of compressor
99
Q

Why do we need bearing spread?

A

We need it for location and to keep in place during installation

100
Q

Bearing crush is used to?

A

For good seating and good heat transfer

101
Q

What are dowels and locking tabs used for?

A

Anti-rotation devices or to keep bearing element from rotating with journal or shaft

102
Q

Why do we have clearance pockets on the compressors and where are they located?

A

They are used to control the output to meet demands, they are located at the head end.

103
Q

What is the main reason for keeping rod runout within limits

A

To limit wear and increase sealing

104
Q

Which rider ring is used if it passes over a valve port?

A

The uncut rider ring

105
Q

Which ring is used by itself and where is it located?

A

The Pressure Breaker Ring

It is located closest to the cylinder or pressure end

106
Q

What are liquid cooled packing case is normally used for?

A

Oil free applications

107
Q

What happens if the surface of the piston rod is scratched or damage?

A

it will ruin the seal of the packing

108
Q

We inspect and measure cylinders to see if they are?

A
  • Straight
  • Round and
  • Within specified dimensions
109
Q

What is the purpose of the connecting rod?

A

To convert rotating motion to reciprocating motion

110
Q

Where are cracks likely to be located on the crank?

A

The corner of the fillets, and around oil holes

111
Q

How does a dynamic system make pressure?

A

It restricts flow to get pressure

112
Q

When does valve flutter or multiple impacting occur and what do you do to correct it?

A

It occurs at high speeds and is fixed by using a dampening disk

113
Q

What should be done to the valve chair bolt when removing the valve?

A

The valve chair boat should always be backed off before removing the valve cover

114
Q

Is compressor rotation the daily check?

A

No, only when a major service is done

115
Q

What are some examples of daily checks?

A
  • Oil levels
  • Fluid levels
  • Water temperature
116
Q

What is the purpose preload?

A

Is used to compensate for thermal expansion so the rod runs true at operating temperature

117
Q

In lubricated packing where is the oil distributed?

A

It enters through the flange at the top and it is directed near the pressure side, but not all the way to pressure breaker

Millwright 2nd Year 2018 (4 decks)

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