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Book 1 - 5th Power Engineering > chapter 8 > Flashcards

chapter 8 Flashcards

1
Q

The differential spring in a pressure controller

a. Is used on the modulating method of burner control
b. Is subtractive
c. Controls the spread between the boiler cut-in and cut-out points
d. Protects the boiler from over pressure

A

c

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2
Q

A firetube boiler is the boiler that is most likely to cause a serious boiler explosion because:

a. Contains a large volume of water
b. Has high fuel input
c. Is not required to have a safety valve
d. All of the above

A

a

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3
Q

The low air pressure fuel cutoff switch acts to:

a. Shut down the burner on on loss of combustion air pressure
b. Maintain constant firing rate
c. Prove combustion air before the blower will start
d. Drive the combustion dampers to match the firing load

A

a

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4
Q

The air damper positioner on a burner must

a. Match combustion air input to fuel input
b. Close on loss of flame
c. Maintain a constant safe airflow through the boiler during off cycles
d. Match fuel input to combustion input

A

a

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5
Q

Ideally, the cut-out pressure of a boiler’s high limit control should not exceed ______ % of the safety valve setting

a. 75
b. 90
c. 95
d. 100

A

b

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6
Q

The aquastats used on hot water boilers do not have an adjustable differential

True
False
A

false

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7
Q

Typically, the two methods of burner control used with hot water boilers are:

a. Modulating and off/on
b. High-fire/low-fire and on/off
c. Modulating and high-fire/low-fire
d. Modulating and off/off

A

a

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8
Q

A boiler burner that is regulated by the high-fire/low-fire method has a total of _________ pressure controllers or temperature controllers.

a. 2
b. 1
c. 3
d. There isn’t enough information given in the question to determine

A

c

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9
Q

On a boiler that is regulated by the high-fire/low-fire method, the controls are set so that the boiler starts and stops on:

a. The boiler fires continuously
b. high fire
c. Either mode, depending on load
d. Low fire

A

d

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10
Q

With the On-Off method of controlling a burner

a. The firing rate adjusts continually to load
b. Operates at maximum efficiency compared with other methods of burner control
c. The burner fires at a constant rate that is sufficient to maintain the full load
d. Two firing rates are available so that one firing is on lead while the other is on lag

A

c

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11
Q

With the On-Off method of controlling a burner

a)Operates at maximum efficiency compared with other methods of burner control
b) Two firing rates are available so that one firing is on lead while the other is on lag
c) The firing rate adjusts continually to load
d) The burner fires at a constant rate that is sufficient to maintain the full load

A

d

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12
Q

Limit or safety controls are also known as

a) Aquastats
b) Differential controls
c) Operating Controls
d) Interlocks

A

d

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13
Q

The operating control on a high fire-low fire style burner controls:

a) both the low fire and high fire burners or nozzles
b) neither the low fire nor the high fire burners or nozzles
c) the low fire burner or nozzle
d) the high fire burner or nozzle

A

c

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14
Q

When blowing down a boiler equipped with a quick opening valve and a slow opening valve, the quick opening valve is:

a)A globe valve
b) Opened first and closed last
c) A plug valve
d) Opened last and closed first

A

b

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15
Q

The low air pressure switch compares windbox air pressure to:

a)Atmospheric pressure
b) Water pressure
c) Fuel pressure
d) Boiler pressure

A

a

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16
Q

The differential spring in a pressure controller

a) Controls the spread between the boiler cut-in and cut-out points
b) Protects the boiler from over pressure
c) Is subtractive
d) Is used on the modulating method of burner control

A

a

17
Q

The device used on a hot water boiler to maintain the water temperature is the

a) Aquastat
b) Modulator
c) Immersion bulb
d) Bellows

A

a

18
Q

The air damper positioner on a burner must

a) Close on loss of flame
b) Match fuel input to combustion input
c) Maintain a constant safe airflow through the boiler during off cycles
d) Match combustion air input to fuel input

A

d

19
Q

Three of the four distinct methods of burner operation control for a steam boiler are:
1. On-Off control
2. Damping control
3. Modulating control
4. High Limit control
5. Multiple burner control

A.2, 3, 5
B.1, 3, 4
C.3, 4, 5
D.1, 2, 3
E.2, 3, 4

A

b

20
Q

The high limit control can be tested by:

A.Slowly covering the air supply to the fan
B.Quickly closing the main burner shut-off valve
C.Slowly raising the boiler pressure above the operating setpoint
D.Closing the main gas valve quickly
E.Slowly closing the main gas valve

A

c

21
Q

The low gas pressure cut-off switch can be tested by:

A.Slowly covering the air supply to the fan
B.Closing the main gas valve quickly
C.Slowly raising the boiler pressure above the operating setpoint
D.Slowly closing the main gas valve
E.Quickly closing the main burner shut-off valve

A

d

22
Q

An automatic/manual selector switch is provided on a boiler with the following burner control system.

A.Modulating fire control
B.High limit fire control
C.On-Off fire control
D.Operating limit fire control
E.High-Low fire control

A

a

23
Q

The high limit control of a steam heating boiler should operate at the:

A.Cut-out pressure of the operating control
B.Maximum allowable working pressure
C.Blowdown pressure of the safety valve
D.Set pressure of the safety valve
E.Between the set pressures of the operating control and safety valve

A

e

24
Q

Damper position switches are found on boilers with the following burner control systems:
1. On-Off control
2. High-Low control
3. Modulating control
4. High Limit control

A.3, 4
B.1, 3
C.2, 3
D.4, 5
E.1, 2

A

c

25
Q

The Modulating fire control system uses _____ to control the combustion process.

A.Variable fuel/air flow
B.Air on-off control
C.Fixed fuel flow and variable air flow
D.Fixed air flow and variable fuel flow
E.Fuel on-off control

A

a

26
Q

If the pressure of the gas supplied to the burner increases beyond the maximum required for safe combustion the _____ switch will de-energize the fuel valve.

A.Low water level
B.High gas pressure
C.Low gas pressure
D.High limit
E.Low air pressure

A

b

27
Q

Controls found on heating boilers include:
1. Operating controls
2. Pressure relief controls
3. High limit cut-off switches
4. Condensate level controls
5. Low limit cut-off switches

A.1, 2, 3
B.2, 3, 4
C.1, 3, 5
D.3, 4, 5
E.3, 4, 5

A

c

28
Q

During boiler operation if the combustion air pressure drops to low the _____ switch will de-energize the fuel valve.

A.Low water level
B.Low gas pressure
C.High gas pressure
D.Low air pressure
E.High limit

A

d

29
Q

the burner control that continually adjusts the firing rate to maintain the boiler pressure at a constant value is called __________________

a. on-off
b. high - low
c. modulating
d. high limit

A

c

30
Q

the name of the second spring that is used to increase the span between cut-in and cut-out is the ______________ control

a. differential
b. high - low
c. mid spring
d. set point

A

a

31
Q

the simplest type of burner operating control used on low capacity boilers is the________________-

a. modulating
b. high-low
c. high limit
d. on-off

A

d

32
Q

The device used on hot water boilers to maintain the water temp is the:

a.immersion bulb
b. bellows
c. modulator
d, aquastat

A

d

33
Q

the name of the switch used to start or stop the boiler is the ___________

a. selector
b.burner
c. flame control
d. high-low

A

b

34
Q

if the low air pressure switch is activated it will close the

a. damper
b. main fuel valve
c. pilot gas valve
d. feedwater valve

A

b

35
Q

the cut out pressure setting for a high pressure safety control used to protect a low pressure steam boilert will be:

a.103 kPa
b. lower than the cut-out pressureof the operating control
c. just below the popping pressure
d. no higher than 200 kPa

A

c

36
Q
A

Book 1 - 5th Power Engineering (20 decks)

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