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TEST 2 - IPT Flashcards

1
Q

List the four functions of hydraulic fluid

A
  • power transmission
  • lubrication
  • sealing
  • cooling
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2
Q

The bulk modulus of an oil is independent of the temperature

A
  • false
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3
Q

The compressibility of petroleum based oils is approximately 0.5% per 1000psi

A
  • true
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4
Q

High viscosity oil may cause excess internal leakage in components

A
  • false
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5
Q

A thick fluid that pours and flows slowly is said to have a low viscosity

A
  • false
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6
Q

The viscosity of hydraulic fluid decreases as the temperature rises

A
  • true
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7
Q

The viscosity of oil is independent of any pressure changes

A
  • true
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8
Q

The viscosity of grease will change as the shear rate changes

A
  • true
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9
Q

List four possible outcomes of having the viscosity of hydraulic fluid too high

A
  • power will be lost overcoming friction
  • the system will operate at a high temperature due to internal friction
  • there will be increased pressure drops throughout the system
  • systems may operate more slowly, if resistance to flow in the pressure line causes the relief valve to open
  • pumps may cavitate due to low suction pressures
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10
Q

List four possible outcomes of having the viscosity of hydraulic fluid too low

A
  • cylinder may creep due to valve leakage
  • the pump output may be reduced due to internal leakage
  • actuators may slow down due to seal leakage
  • the temperature may increase when pressurized fluid leaks back to a low pressure area with no work being done
  • there may be increased wear and friction due to metal to metal contact of sliding parts
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11
Q

List the two methods used to measure viscosity

A
  • absolute (dynamic)

- kinematic (relative)

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12
Q

What is the SI unit of absolute viscosity?

A
  • pascal second
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13
Q

What is the SI unit of kinematic viscosity?

A
  • mm2/second
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14
Q

An oil is designated as ISO VG 68. What would be the approximate viscosity in Centistokes at 400C?

A
  • 68
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15
Q

The viscosity index (VI) of an oil will change as the temperature changes

A
  • false
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16
Q

Equipment that is subject to low temperature starts will require fluid that has a high viscosity index

A
  • true
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17
Q

The result of plotting a viscosity versus temperature graph is a straight line

A
  • false
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18
Q

The maximum start up viscosity for the system is usually set by the ???

A
  • pump
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19
Q

The temperature at which wax crystals begin to form and change the appearance of the oil is known as the ???

A
  • cloud point
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20
Q

An oil that is at its flash point temperature will spontaneously ignite

A
  • false
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21
Q

The fire point temperature of an oil is higher than the flash point

A
  • true
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22
Q

List four factors that will increase the oxidation rate of an oil

A
  • high temperatures
  • high pressures
  • agitation
  • catalysts
  • contaminants
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23
Q

An oil with a high degree of demulsibility will ???

A
  • require a short time to separate from water
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24
Q

A hydraulic system designed to operate on petroleum based fluid can not be converted to operate on fire resistant fluid

A
  • false
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25
Q

All fire resistant fluids must not be allowed to come into contact with water

A
  • false
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26
Q

All biodegradable oils are synthetically manufactures

A
  • false
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27
Q

Which of the following contaminants is the major cause of wear and sticking problems

A
  • solid contaminants
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28
Q

Solid contaminant particles that are too large to enter the clearance space between moving parts will

A
  • eventually cause problems
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29
Q

List four sources of contamination

A
  • maintenance
  • built in
  • ingressed
  • internally generated
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30
Q

New hydraulic fluid is alway completely free of contamination

A
  • false
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31
Q

After assembling a new system what procedure should be followed to reduce the amount of built in contamination

A
  • flush with a low viscosity hydraulic fluid
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32
Q

List four likely entry points for ingressed contamination

A
  • piston rod seals
  • pump shaft seals
  • motor shaft seals
  • reservoir vents
  • pipe and tubing connections to the reservoir
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33
Q

To prevent the contaminants present in air from contaminating the hydraulic fluid a rubber or plastic membrane may be used in the reservoir

34
Q

Contamination particles that are the result of component wear are not usually a problem because they are generally very soft

35
Q

The rate of erosive wear will be increased if the fluid contains solid contaminants

36
Q

Below a certain size, solid particles are usually referred to as silt. What is this size?

A
  • 5 micrometers
37
Q

The ISO contamination code of 19/14 is cleaner than 17/11

38
Q

The maximum operating pressure and the system components has a direct bearing on the required cleanliness level for a hydraulic system

39
Q

The pump is always the component that sets the cleanliness requirements for a hydraulic system

40
Q

A mesh strainer with a US Sieve number of 270 (53 micrometer opening) would have an absolute rating of

A
  • 53 micrometers
41
Q

A mesh strainer with a US Sieve number of 270 (53 micrometer opening) would have an nominal rating of

A
  • less than 53 micrometers
42
Q

The ISO standard for rating hydraulic filters is

A
  • Beta ratio
43
Q

During a filter test for beta ratio using particles 5 micrometers and larger, a filter had 10000 particles the upstream side and 80 particles on the downstream side of the filter. The filter would be rated at

44
Q

For a filter rated at b5=150, the removal efficiency would be

45
Q

Name two sources of contaminant ingression that can be controlled by filters

A
  • air entering the reservoir as the fluid level drops

- fluid being added to the system

46
Q

The relief valve must always be between the pump and a bypass type filter

47
Q

The relief valve must always be between the pump and a non bypass filter

48
Q

Return line filters may have to deal with flow rates greater than the maximum pump output

49
Q

Component isolation filter should have the highest removal efficiency of all the system filters

50
Q

A typical surface type filter would be a mesh strainer

51
Q

When low micron filtration is required, a strainer is usually used

52
Q

Most depth type filters can be reused by washing

53
Q

The pressure drop through a filter and housing is independent of the flow rate

54
Q

Which type of line is most likely to return fluid to the reservoir with no filtration?

55
Q

What is the best way to add fluid to the system?

A
  • use a pump and filtration system piped directly into the circuit or reservoir
56
Q

Why should a system of regularly taking oil samples for laboratory analysis be set up?

A
  • to check for filter effectiveness, component wear and general fluid quality
57
Q

Compared to the pump displacement per minute, what is the recommended size for reservoirs?

A
  • 2 to 3 times
58
Q

Return lines to the reservoir should terminate below the fluid level

59
Q

List 5 common features found on reservoirs

A
  • oil level indicator
  • filler/breather
  • internal access doors
  • baffles
  • drain plug
  • temperature gauge
60
Q

A vertical sight glass is preferable to a dipstick for monitoring the reservoir fluid level because

A
  • there is no possibility of introducing contaminants
61
Q

List the three basic accumulator types

A
  • weight loaded
  • spring loaded
  • gas loaded
62
Q

Of the three basic types of accumulators, which one will produce a constant pressure when discharging fluid?

A
  • weight loaded
63
Q

The spring loaded accumulator can only be mounted in a vertical position

64
Q

One factor that affects the pre-charge pressure on a gas loaded accumulator is the displacement of the hydraulic pump

65
Q

What is the usual type of gas used for pre-charging gas loaded accumulators?

66
Q

Which type of gas must not be used for pre-charging gas loaded accumulators?

67
Q

List three types of gas loaded accumulators

A
  • piston
  • bladder
  • diaphragm
68
Q

List two of the disadvantages the piston type accumulator has when compared to the other gas loaded types

A
  • slow response time

- possibility of seal leakage

69
Q

If the piston area ratio of an intensifier is 8 to 1, what is the output pressure if 4000KPa is applied to the input (large piston end)

70
Q

If the piston area ratio of an intensifier is 6 to 1, what is the output pressure if 500 psi is applied to the input?

71
Q

An intensifier with an area ration of 6 to 1 require 1-1/2 gallons of hydraulic fluid at the inlet when moving through its full stroke. What amount of fluid will be discharged from the outlet?

A
  • 1/4 gallon
72
Q

The major advantage of the Bourdon tube type pressure gage is that it has no moving parts

73
Q

A bourdon tube type of pressure gage is calibrated from 0 to 2000 psi, which of the following readings would be most accurate?

74
Q

List two devices that should be installed with the pressure gage to increase pressure gage life

A
  • pressure snubber

- venting isolation valve

75
Q

List two types of pressure switches

A
  • bourdon tube type

- piston type

76
Q

Which type of pressure switch does not have any possibility of dynamic seal leakage?

A
  • bourdon tube type
77
Q

The operating temperature of petroleum based oils should normally not be higher than

78
Q

Heat exchangers used with hydraulic systems are always used to remove heat from the system

79
Q

The shell and tube cooler uses liquid as a medium to transport heat away from the system

80
Q

Immersion type heat exchangers can only be used as heaters to add heat to the hydraulic system

TPC (5 decks)

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