INST 6002 - Boiler Programming Controls (Chp 10)

Question 1

Which of the following “IS NOT A POSSIBLE CAUSE” of the damper motor failing to operate?

A) A loose or jammed linkage
B) High-low fire or modulating control set improperly
C) Loss of fluid in the motor float chamber
D) Motor contacts malfunctioning
E) Positioning switch in wrong position

Answer 1

C) “LOSS OF FLUID”in the motor float chamber

Question 2

The “operating pressure control” will control the:

A) Steam pressure in the steam header
B) Water pressure to the boiler
C) Boiler furnace pressure
D) Gas pressure to the burner
E) Steam pressure in the boiler

Answer 2

E) “Steam pressure” IN THE BOILER”

Note: IN THE BOILER

Question 3

Automatic boiler programming controls may use:

A) Interlocking devices
B) High-low fire control
C) All answers shown
D) An ON-OFF or two-position control switch
E) A modulating control system

Answer 3

C) All answers shown

Question 4

To meet the programmed control startup conditions, the automatic boiler liquid fuel manual valves should be opened:

A) With the automatic main burner fuel valve
B) After the automatic main burner fuel valve opens
C) Prior to pre-purging
D) Immediately after completion of the pilot flame trial
E) After pre-purge and just prior to pilot ignition

Answer 4

C) Prior to pre-purging

Question 5

When the safety devices and limit controls on boilers, are activated, they shut off the:

A) Fuel flow
B) Feedwater flow
C) Steam flow
D) Flue gas flow
E) Combustion air flow

Answer 5

A) Fuel flow

Question 6

If “pilot ignition” has “not taken place”, the oil fired boiler:

A) Will restart when low airflow switch is closed
B) Will be able to be restarted immediately
C) Will start after reset
D) Does not need to be purged again
E) Will attempt restart after reset and the lock out switch has cooled down

Answer 6

E) Will “attempt restart after reset” and the lock out switch has cooled down

Question 7

On a gas fired automatic boiler a normal programmed start-up takes approximately:

A) 55 seconds
B) 105 seconds
C) 120 seconds
D) 27 - 40 seconds
E) 70 seconds

Answer 7

B) 105 seconds

Question 8

Boiler furnaces are purged:

A) So that the programmer has time to verify permissiveness of interlocks
B) So that combustibles are fully removed prior to ignition
C) So that the operator can check the fuel and water systems
D) In order to allow combustion gases to accumulate prior to ignition
E) To allow any hot refractory to completely cool

Answer 8

B) So that “COMBUSTIBLES” are FULLY REMOVED prior to ignition

Question 9

In the following start up and shut down sequence for gas fired boilers, which steps are out of order?

1. Starting switch closed. Operating control in cut in position. Master relay energized. Timer starts. Fan starts. Programmer takes control of damper motor. Purge initiated at maximum airflow.
2. Low airflow switch closed.
3. Damper placed in low fire position for purge at reduced flow. Low fire switch must close for ignition to take place.
4. Flame relay switch is open.
5. End of purge period. Ignition energized. Pilot gas valve opens. Start of trial period. When scanner senses pilot flame, the flame relay closes.
6. Main gas valve is energized, main burner lights. Start of main burner ignition.
7. Pilot valve and ignition de-energized. Programmer releases control of damper motor. Damper and fuel valve are now placed in high fire position by the modulating operating control if the boiler is on automatic control, or they are placed on the demand setting of the firing rate selector switch if the boiler is on manual control.
8. End of start cycle, beginning of normal firing period. Timer motor stops, burner and blower remain in operation until heat demand is satisfied and operating controls reach their cut-out points.
9. Operating control opens. Master relay and fuel valve de-energize. Scanner ceases to sense flame. Flame relay opens. Timer restarts. Programmer takes control of modulating motor and holds it in low fire position. Start of after-purge period at low air flow.
10. End of after-purge period. Blower motor stops, timer stops. The system is now ready again for a restart whenever operation control reaches its cut-in point.

A) 5 & 6
B) 1 & 2
C) 10 & 5
D) 8 & 9
E) None are out of order

Answer 9

E) None are out of order

Question 10

During the startup of an “OIL FIRED BOILER”at the end of the purge the timer:

A) Shuts down
B) Energizes the ignition transformer
C) Opens the pilot valve
D) Goes through an ignition trial
E) Opens the fuel valve

Answer 10

B) Energizes the “IGNITION TRANSFORMER”

Question 11

For “programmed startup of boilers” with “NATURAL DRAFT”the electrical circuit to the main gas valve is closed:

A) When the flame detector senses the Pilot flame
B) When the water level is high
C) Before purging
D) While purging
E) During pilot ignition

Answer 11

A) When the “FLAME DETECTOR SENSES”the Pilot flame

Question 12

Which of the following “is not required before” starting using programming control?

A) Main power on
B) Water level above cutoff
C) Water temp below cut in
D) Gas pressure above low pressure cutoff
E) Main gas valve closed

Answer 12

E) Main gas valve closed