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Test Review > Pneumatics, Vacuum, heat exchangers dryer test > Flashcards

Pneumatics, Vacuum, heat exchangers dryer test Flashcards

1
Q

warmer the air the more moisture it can hold

true

False

A

True

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2
Q

relative humidity compares the amount of water a sample of air holds to the maximum amount it could hold if fully saturated

true

False

A

True

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3
Q

if a cubic foot of air has the capacity to hold 11 grains of moisture but has 5 grains of moisture, then it is said to have _______________ % relative humidity

50

45

40

35

A

45

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4
Q

if the air is cooled past 100 % relative humidty, then condensation will result. this is called the_________

dry air point

specific humidity point

vapour point

dew point

A

Dew point

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5
Q

water / moisture in a compressed air system needs to be separated and removed by

air receivers

after coolers

dryers

all the above

A

All of the above

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6
Q

adsorption dryers work on the principle of ________ of molecules in a thin layer onto the desiccant

a chemical bond

vapourization

adheasion

regeneration

A

Adhesion

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7
Q

the process of removing the accumulation of moisture from the dryer bed is called____________ which uses ________________

regeneration, heat

regeneration, absoption

regeneration, purge gas

both the 1st and 3rd answer are correct

A

Both first and third

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8
Q

about __________% of dry air is used for regeneration in heater-less dryers

10-15

20-30

40-60

1-2

A

10-15

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9
Q

the ideal system for adsobtion dryers is a twin tower system with ___________ which reduces the amount of cycle times and compressed air usage

cams and mechanical valves

electronic switches and automatic valves activated by the dew point sensor in the system

electronic switches and automatic valves

none of the above

A

Electric switches and automatic valves activate by the dewpoint sensor in the system

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10
Q

because desiccant can break down of become contaminated with oil, the air drying system needs to be protected with coalescing filters

true

False

A

True

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11
Q

in the regeneration cycle, the purge air is _____________ to help reduce compaction and make removal of moisture faster

sped up

deflected

reversed

cooled

A

Reversed

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12
Q

.a heated adsorption dryer with internal heaters uses about______% of the dryed air.

2

5

10

12

A

2

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13
Q

the moist gas from the regeneration cycle (purge gas) in not explosive or hazardous, then it can be vented to the atmosphere. otherwise it has to be cooled and ran thru a moisture separator and re-introduced to the dryer inlet gas stream

true

false

A

True

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14
Q

the rotary drum dryer has 2 separate air flows going thru it. the hot dry gas passes thru____ % of the rotor and the moist gas passes thru ______ % of the rotor

50, 50

75, 25

25, 75

60, 40

A

25,75

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15
Q

absorption dryers use __________ in the process to dry the air

adheasion

vaporization

chemical bond

all the above

A

Chemical bond

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16
Q

chemical dryers cannot be regenerated because they dissolve or melt when combined with moisture

true

false

A

True

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17
Q

in the liquid dehydration process, an absorption agent such as ethylene glycol is sprayed thru nozzles and as the air travels down thru it, it is scrubbed and moisture absorbed

true

False

A

False

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18
Q

to remove the moisture from the glycol, it is ran thru a ______________where it is heated to 200 C and moisture is evaporated

heat exchanger

vapourizer

steam cleaner

still

A

Still

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19
Q

refrigeration dryers use the dew point reduction method to remove moisture from the air thru the use of an air circuit and a refrigeration cycle

true

False

A

True

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20
Q

latent heat is heat that is sensed by a thermometer

true

False

A

False

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21
Q

in mechanical dryers, water sprayers are added to cool down the air before it strikes the baffles that create a torturous path

true

false

A

False

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22
Q

colescing filter elements can effectively remove particles down to a size of _________ microns

0.001

0.0001

0.01

0.1

A

.01

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23
Q

the best way to determine if a dryer is taking out moisture, is to

check the dessicant

watch the cycle times

measure the flow rates

measure the dew point of the air

A

Measure the dew point

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24
Q

wire drawing is

used to seal flanges

process of air movement thru the dessicant

a fine groove cut in a sealing surface (caused by high pressure gas)

none of the above

A

A fine groove cut in a sealing surface (caused by high pressure gas)

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25
Q

most dryers that run below 175 degrees C, use a teflon valve seat

true

False

A

True

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26
Q

in a pneumatic system, the compressor intake should be in a __________ place because the air is denser

wet

cool

hot

A

Cool

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27
Q

when compressing with a reciprocating compressor, you need a _____________ to help dampen pulsations

after-cooler

minimum of bends in the intake

inter-cooler

receiver

A

Receiver

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28
Q

the pneumantic piping system that has the compressor close to its point of use is the

grid

decentralized

loop

none of the above

A

Decentralized

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29
Q

proper sizing of lines in a pneumatic system is important because if the piping is to small, it will

cause moisture in the air supply

cool the air supply

cause a pressure drop in the air supply

create more flow

A

Cause a pressure drop in the air supply

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30
Q

you must eliminate all leaks in a compressed air system because it will cost more to produce the needed CFM

true

False

A

True

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31
Q

if an FRL is installed backwards, it would

gum up the regulator with oil

remove lubrication

work normally

the 1st and 2nd answers are correct

A

Both first and second answers

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32
Q

in an FRL, the filter uses ___________ and the lubricator uses ________ to work properly

centrifugal force, venturi

venturi, centrifugal force

none of the above

regeneration, desiccant

A

Centrifugal force, venturi

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33
Q

water traps use a _________ to expel moisture automatically from the unit

pressure drop

deflector plate

float valve

hand valve

A

Float valve

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34
Q

a 5/3 valve has ________ and ____________ positions

3 ways, 5

5 ways, 3

5 ports, 3

both the 2nd and 3rd answers are correct

A

Both second and third answers are correct

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35
Q

a pressure reducing valve has a normally _____________flow path thru it

closed

open

both open and closed

none of the above

A

Open

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36
Q

venting regulators will protect the _______________ from over pressure

upstream section

downstream section

does not protect any part of the system

vent to the receiver

A

Downstream section

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37
Q

a DCV is identified by

of controlled connections

of switching positions

method of activation

all the above

A

All of the above

38
Q

external and internal pilot operation, are valves activated

manually

by air

electrically

all the above

39
Q

you would use a 4/2 valve to activate

a single acting cylinder

double acting cylinder

a center position in the valve

all the above

A

Double acting Cylinder

40
Q

you would use a 5/3 valve to

control as cylinder with the valves center position

control a single acting cylinder

control a rotary motor with the valves center position

both the 1st and 3rd answers are correct

A

Both first and Third Answers are correct

41
Q

the needle valve is the most accurate flow control valve for metering flow

true

False

42
Q

a quick exhaust valve is used to expel gas at the

directional control valve

cylinder

receiver

compressor

43
Q

excess flow valves are used on air hoses that are larger than 1/2”, to eliminate hose whipping

true

False

44
Q

double acting cylinders use _____________ to slow down the piston at the end of each stroke

packing

o-rings

stop tubes

cushions

45
Q

when using flow controls to slow down the movement of a cylinder in an circuit, you would _________ the air with the flow control

meter-in

meter-out

46
Q

air logic applications are used in systems that have

an explosive environment

a very wet environment

air gauging

all the above

A

All of the above

47
Q

which rotary motor uses a swash plate to control speed of actuation

vane

piston

turbine

gear

48
Q

you have a cylinder that is sticking when extending and retracting. what may the problem be

rod packing to tight

pilot pressure is to low to shift spool valve all the way

a bent piston rod

all the above

A

All of the above

49
Q

when reassembling and installing parts, you should aways check the component for proper operation

true

false

50
Q

if you have a system that you want to protect an operator from getting their hands caught in an unsafe area, you would have a system that would require the operator to hold both hands on 2 different levers that needs both levers moved at the same time to operate the equipment

true

false

51
Q

when thawing a frozen valve, make sure to apply heat as quick as possible to limit the possibility of a fire

true

false

52
Q

if you have excessive pressure in part of a pneumatic system, you will look for

a flow restriction

leak in the system

pressure regulator set to high

pressure regulator set to low

A

Pressure regulator set to high

53
Q

if you have a cylinder moving inconsistently, you will look for

bent piston rod

damaged piston seals

inconsistent air pressure

all the above

A

All of the above

54
Q

if a cylinder body seal is leaking, you will look for loose cylinder tie rods

true

false

55
Q

a pneumatic valve is blowing to exhaust when actuated. what is the problem

valve seals are leaking

spool damage

valve to base gasket is faulty

all the above

A

All of the above

56
Q

a poppet is chattering in a pneumatic system. the problem is most likely

the air supply pressure is too low

the pilot pressure is too low

air supply pressure is too high

both the first and second answers are correct

A

Both first and second answers are correct

57
Q

the actuator cylinder is drifting in a pneumatic system. The problem could be a piston seal is leaking

true

false

58
Q

vacuum systems are limited to ________ of vacuum pressure to work with

14.7 psi

29.92 ‘Hg

29.92 psi

  1. Kpa
59
Q

plumbing size for pipe in a vacuum system must be as small and short as pradtical for static systems

true

False

60
Q

if your vacuum system has back pressure, this will cause the system to be more efficient

true

False

61
Q

when hooking up a vacuum system to a cylinder, you would hook the vacuum up to the _________ port to make it extend

rod end

cap end

it works the same way as a pressure system

none of the above

62
Q

if you had an air valve that you are going to use as a vacuum valve, you would hook up the pressure port to atmosphere and the exhaust port to the vacuum source

true

false

63
Q

.you would use a vacuum relief valve for static systems. this would allow the pump to be cooled and lubricated. the system would also use less horsepower

true

false

64
Q

when lifting and holding with suction cups in a vacuum system, you would calculate the area under the cup and times it by the number if inches of Hg (mercury) to find the weight the cup could hold

true

False

65
Q

you want to use _________ seals on your cylinder’s piston for vacuum systems as they produce the least amount of friction

metal

O-ring

leather cup

none of the above

A

Leather cup

66
Q

you can use some vacuum systems in combination (as a vacuum system and as a pressure system). the system will produce high pressures ( 100 psi) on the exhuast side of the pump

true

False

67
Q

if you had a 3” suction cup that has a vacuum of 20” Hg pulling on it, how much could you lift?
f = p x a 2’ Hg = 1 psi

31 lbs

51 lbs

61 lbs

71 lbs

68
Q

when replacing gaskets in vacuum pumps, it is important to have the proper thickness for proper sealing inside the pump

true

false

69
Q

heat exchangers have the ability to cool or heat the air and or liquid to a constant temperature

true

False

70
Q

heat exchangers have 3 basic means of heat transfer at work. they are conduction, covection and radiation. the one the uses CONTACT between the fluid and metal surface is

conduction

convection

radiation

A

Conduction

71
Q

the rate of heat transfer is influenced by the amount of direct scrubbing action that is present in the fluid flow. this scrubbing action is caused by

laminar flow

forced convection

turbulent flow

forced flow

A

Turbulant flow

72
Q

there are many different flow path arrangements. the one that is the most efficient at cooling is the

parallel flow

counter flow

cross flow

mixed flow

A

Counter flow

73
Q

in plate heat exchangers. it is important to have the spacing of the plates close together. they should be spaced at _______________ apart

6 to 10 mm

11-15 mm

16-20 mm

2-5 mm

74
Q

spiral heat exchangers are very efficient because they have a true counter flow and create their owm scrubbing action

true

False

75
Q

cooling towers can be divided into 2 classes. they are forced draft and induced draft

true

False

76
Q

forced draft is when the air flow is pulled out of the cooling tower

true

False

77
Q

double pipe heat exchagers are able to

handle high pressures

only handle low heat duties

be connected in series or in parallel

all the above

A

All of the above

78
Q

shell and tube heat exchangers have

large surface areas for heat transfer

the capability of handling only low temperatures and pressures

the capacity of handling high temperatures and pressures

both the 1st and 3rd answers are correct

A

Both first and third answers are correct

79
Q

the tubes are commonly expanded into the __________ to form a seal against leakage

shell

tube sheets

baffles

head cover

A

Tube sheets

80
Q

an advantage of the u-tube heat exchanger over the fixed tube heat exchanger is

the tubes are cleaned easier

the outside of the tubes are cleaned easier because the tubes can be taken out of the shell

there are inspection doors that let you access the outside of the tubes

it has a higher efficiency

A

the outside of the tubes are cleaned easier because the tubes can be taken out of the shell

81
Q

the tube sheet layout that allows for the most tubes for a given size exchanger is the

30 degree style

45 degreee style

the 90 degree style

they all create the same number of tubes

A

3o degree style

82
Q

baffles in heat exchagers help

support the tubes to prvent vibration

cause turbulence

prevent dead bypass areas

all the above

A

All of the above

83
Q

3 longitudinal baffles will make the heat exchanger a _____________ pass exchanger

1

2

3

4

84
Q

floating head shell and tube exchangers will allow 1 tube sheet to float which allows the exchanger to use fluids of an extremely high temperature differential

true

False

85
Q

the only heat exchanger that is used where it is undisireable to allow the mixing of the tube side and shell side fluids in the exchanger is the

floating head

u-tube

fixed tubesheet shell

double tube sheet

A

Double tube sheet

86
Q

heat transfer in a heat exchanger is affected by __________________

fluid flow

temerature differentials

contact time

all the above

A

All of the above

87
Q

fluid films are formed next to the tube walls. they decrease the heat transfer. to help increase heat transfer thru the tubes you can increase the

temperature

pressure

velocity

all the above

88
Q

hydrostatic testing is commonly used to check heat exchangers for leaks. the standard pressure used in hydro-testing is

the same pressure as the system

1.5 times system pressure

2 times system pressure

3 times system pressure

A

1.5 times the system pressure

89
Q

when first applying the flows of fluid into the heat exchanger, make sure the _____________valve is opened so all air in the exchanger can be purged out

vent

shuttle

butterfly

none of the above

90
Q

when purging a dryer or heat exchanger system of toxic gases, you would use

nitrogen

carbon dioxide

steam

all the above

A

All of the above

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