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millwright year four > fans and boilers > Flashcards

fans and boilers Flashcards

1
Q

Which firetube boiler is built with a firebox that is not completely surrounded by water?

A

firebox boiler

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2
Q

Which boiler consists of an arrangement of drums and headers interconnected by tubes?

A

watertube

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3
Q

How many fans are used to control the draft through a balanced draft boiler?

A

two: one on the inlet and one on the outlet

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4
Q

Which boiler would be classified as a firebox boiler?

A

HRT

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5
Q

What is the minimum clearance required in front of an access panel on a gas-fired boiler?

A

24” regardless of whether it is insulated or not

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6
Q

What does the installer have to do with the boiler and piping systems before turning them over to the owner?

A

Inspect and test for leak-tight service

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7
Q

What is the cause of the most common problems encountered after start-up of steam boilers and systems?

A

improper cleaning and flushing

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8
Q

What is likely to occur if there is a heavy concentration of dissolved or suspended particles in the boiler water?

A

The water may foam and could cause priming

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9
Q

What should be done if the water in the sight glass is not clear after cleaning and flushing?

A

c) Repeat the cleaning procedure.

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10
Q

What should be done with the results of all pertinent test results during the test, start and balance phases of a system start-up?

A

Record the results and have the results verified.

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11
Q

Where is the appliance’s gross rating taken?

A

boiler nozzle outlet

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12
Q

Where is the appliance’s net rating taken?

A

heat emission units

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13
Q

What does the term pass in boiler terminology mean?

A

the number of times the products of combustion travel the length of the boiler

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14
Q

What is the main advantage of steam over hydronic systems?

A

speed of transmission

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15
Q

What is the usual maximum circulating speed of water for a low-temperature hot water heating system?

A

4 ft/sec

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16
Q

What does load tracking refer to when discussing boilers?

A

the ability of a boiler to respond to changes in steam or hot water demand

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17
Q

Which boiler has the ability to respond to sudden demands for large volumes of steam for a short period of time?

A

bent tube

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18
Q

Which boiler has the ability to handle wide variations in load over a long period of time?

A

water tube

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19
Q

Why is clean condensate considered to be ideal for feeding back into the boiler?

A

Condensate is essentially distilled water, so it contains no dissolved solids

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20
Q

How often should a pop test be done on a safety valve used on an LP steam heating boiler?

A

b) annually

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21
Q

What is the suggested method of determining whether water is flowing through a water feeder valve?

A

Listen with a stethoscope.

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22
Q

What is the most probable cause of the water level in a gauge glass fluctuating rapidly?

A

foaming or priming inside the boiler

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23
Q

What should be done if the pressure in a boiler rises higher than 20 psi during a capacity test on the safety valve?

A

A new valve must be installed that has sufficient capacity to pass the test.

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24
Q

How often should the safety valve be tested on an LP steam heating boiler?

A

at least once for every 30 days the boiler is operating

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25
Q

What is the most important thing to ensure when mounting a new glass into a water level gauge?

A

There should be no direct contact between the glass and the metal of the valve,

26
Q

what are the three purposes of a deaerator?

A

removes air from feed water uses steam and screens Pre heats feed water, better efficiency. Reservoir for feed water.

27
Q

If a boiler has shut down due to a low water condition, what should be done before allowing any water to be fed back into the boiler?

A

Allow the boiler to cool until the crown sheet of the boiler can be touched with the bare hand.

28
Q

What range of pH should be maintained in the water of an LP heating boiler?

A

7 to 9

29
Q

What is the main cause of foaming in a steam boiler?

A

Heavy concentrations of dissolved or suspended particles

30
Q

What are the three (3) types of air required for a space in which a boiler is to be Installed?

A

a) combustion air b) Ventilation air c) Dilution air

31
Q

What determines the type of boiler required in a system?

A

End use

32
Q

List the measurements used to generally net rate low-pressure boilers

A

a) BTU b) EDR

33
Q

List the measurements used to rate high-pressure boilers.

A

a) Boiler horsepower b) Lb of steam per hour c) MBH

34
Q

What devices are installed to control the direction of flow of flue gases through the watertube boiler?

A

baffles

35
Q

What are the three (3) most common configurations for the watertube type of package boiler?

A

a) A-type b) D-type c) O-type

36
Q

what is a Scotch marine boiler classified as a firetube or a firebox type of boiler?

A

firetube

37
Q

What are the two (2) names used to describe the appliances built under the ASME codes for boilers that do not use water or steam as the heat transfer medium?

A

a) vaporizers b) liquid heaters

38
Q

List three (3) kinds of pressure found in operating fan ducts.

A

a) static b) velocity c) total pressure

39
Q

What is a manometer used for?

A

A manometer is a U-shaped tube that is connected to the fan for measuring pressures

40
Q

How can you remove static electricity generated by fans?

A

Ground the rotating element with a ground brush and cable assembly

41
Q

Name the two (2) major types of fans according to flow through the impeller.

A

a) radial flow centrifugal b) axial flow propeller

42
Q

How can control of air through fans be accomplished?

A

inlet louvre, outlet dampers, varying the fan speed

43
Q

What is the purpose of a cold rollover of the fan rotor?

A

A cold rollover is used to confirm that there are no rubbing metal parts and no cracking noises experienced after a fan is overhauled.

44
Q

What is natural draft?

A

A draft caused naturally by heat difference or pressure different, no fans

45
Q

What is forced draft?

A

A draft created by a fan pushing air into the firebox, creating positive pressure throughout the boiler.

46
Q

What is induced draft?

A

A draft created by a fan in between the boiler and stack or chimney, creating a low pressure before it in the boiler.

47
Q

What is the purpose of nitrate testing?

A

To tell you how much salt is in the water, cloud instantly forms when engaged with salt. To much salt changes the heat and can lead to scale.

48
Q

What is a BTU?

A

British thermal unit it is a way to measure temp.The amount of energy needed to raise the temperature of 1 pound of water 1°F at STP is equal to 1 BTU/s

49
Q

What does the term atomizing mean?

A

Breaking the fuel to small amounts to mix better with air to get a better burn.

50
Q

What is the maximum circulating speed of water for a low temperature hot water heating system?

A

4ft/sec

51
Q

What is the purpose of a de-aerator?

A

? removes air from feed water uses steam and screens Pre heats feed water, better efficiency.

52
Q

how many more times space does steam occupy?

A

1600

53
Q

hydrostatic testing should never be done at more than what limit?

A

1 1/2 times boiler limit

54
Q

If too little air is supplied, heat loss will occur due to incomplete combustion, this is distinguished by what?

A

the thick black smoke that is coming out of the stack.

55
Q

If too much air is supplied, heat loss will occur because extra heat is going up the stack with the excess air, this is distinguished by what?

A

the white smoke that is coming out of the stack.

56
Q

Hunting or surging is most pronounced in what type of fan

A

axial

57
Q

hunting or surging is caused by what?

A

it is caused by the changing of air pressures as the fan cycles from high to low pressures.

58
Q

complete the sentence…. Total pressure is arrived at by

A

adding velocity pressure to static pressure.

59
Q

1 HP motor size generates about how many CFM of compressed air flow at about 90 PSI

A

3-4

60
Q

1inch of water produces how many psig?

A

.036 psig

61
Q

1 psig equals how many inches of water

A

27.7

millwright year four (2 decks)

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