INST 6007 - Low Water Fuel Cut-offs and Feedwater Controls (Chp 7)

Question 1

A leak in a condensate return pipe can cause:

A) Less chemicals to be required
B) A low boiler water condition
C) A decrease in system water use
D) Less corrosion in the condensate system
E) Less fuel to be burned

Answer 1

B) A low boiler water condition

Question 2

Equalizing lines on a condensate receiver float chamber:

A) Keep receiver level equal to boiler level
B) Maintain make-up flow equal to condensate flow
C) Eliminate the need for a make-up level control valve
D) Will dampen level fluctuations
E) Maintains equal flow of condensate to multiple boilers

Answer 2

D) Will dampen “level fluctuations”

Question 3

A hot water boiler low water fuel-cutoff:

A) Must have a normally closed switch
B) Cannot be tested during routine boiler operation
C) Should be located on the expansion tank
D) Should be tested weekly during routine boiler operation
E) Cannot be tested

Answer 3

B) Cannot be tested during “routine boiler operation”

Question 4

The low water fuel cut-off may be tested by:

A) Decreasing the firing rate
B) Closing the feedwater inlet valve and opening the blowdown valves
C) Opening the gauge glass drain
D) Adjusting the level controller to maximum
E) Opening the feedwater inlet valve and closing the blowdown valves

Answer 4

B)”CLOSING” feedwater “inlet valve”and opening the blowdown valves

Question 5

Low hot water heating boiler water level can be caused by:

A) Feedwater flow exceeding steam flow
B) High boiler conductivity
C) Excessive blowdown (blowoff)
D) Swell in the boiler
E) Low phosphate level

Answer 5

C) Excessive blowdown (blowoff)

Question 6

When a boiler equipped with a combination feedwater control and low water cutoff device shuts down due to a low water condition:

A) It can be restarted by simply resetting the low water fuel cut-off switch
B) A prepurge of the boiler before it is restarted will not be necessary
C) The feedwater flow to the condensate receiver tank will also stop
D) Level must be restored to above the cut-off line before the unit can be restarted
E) A manual reset switch on the boiler control panel must be used

Answer 6

D) Level must be “restored to above the cut-off line” before the unit can be restarted

Question 7

On LP steam heating boilers, the low water fuel cut-off should operate when:

A) The float chamber drain is opened
B) All of the above
C) The boiler water level drops below 25mm (1 in) in the gauge glass
D) There is excessive blowdown or leakage
E) The boiler feedwater flow is stopped during operation

Answer 7

B) All of the above

Question 8

There are many different types of low water fuel cut-off devices used on boilers. The low water fuel cut-off will operate if the:

A) Mercury switch is tilted
B) All of the above
C) Float drops down in the float chamber
D) Water uncovers both probes
E) Water level in the boiler is not adequate

Answer 8

B) All of the above

Question 9

The low water fuel cut-off must:

A) Not be electronically disabled
B) Not be physically disabled
C) Not have isolation valves installed
D) Be repaired immediately on detection of failure
E) All of the above

Answer 9

C) Not have isolation valves installed

Question 10

Relief valve discharge due to overfiring a hot water boiler can cause:

A) High level in the expansion tank
B) High level of solids in boiler water
C) Low system water temperature
D) Low boiler water level
E) Backflow to city domestic water

Answer 10

D) Low boiler water level

Question 11

Feedwater pump failure:

A) Causes the feedwater temperature to rise
B) Causes a low water condition in the boiler
C) Causes the level in the hotwell to drop
D) Increases the load on the deaerator
E) Causes the feedwater supply pressure to increase

Answer 11

B) Causes a low water condition in the boiler

Question 12

The CSA code B51-09, Part1, 6.3.2.2 states that automatically fired hot water boilers not under continuous attendance by a certified operator must be equipped with a low water fuel-cutoff which:

A) Can also activate an alarm
B) Must be a manually reset device
C) May be equipped with isolation valves to isolate it from service
D) Must be a normally open switch
E) Cannot be rendered inoperative or tampered with

Answer 12

E) Cannot be rendered inoperative or tampered with

Question 13

In nearly all LP steam heating systems the feedwater:

A) Requires daily close scrutiny of chemical values
B) Requires preheating in an economizer
C) Is usually condensate
D) Is a high make-up percentage
E) Must be deaerated

Answer 13

C) Is usually condensate

Question 14

“Overheating of boiler” heating surfaces due to low water:

A) Can be prevented with proper water treatment
B) Will cause a furnace explosion
C) Cannot occur if the boiler is a hot water unit
D) Is the main cause of boiler failure
E) Can be eliminated with a low water fuel-cutoff

Answer 14

D) Is the “main cause” of boiler failure

Question 15

The low water fuel cut-off on steam boilers will operate if:

A) The low side connection valve is closed
B) The high side connection valve is closed
C) The drain valve is closed
D) The float chamber drain valve is opened
E) The feedwater regulator fails open

Answer 15

D) The float chamber drain valve is opened

Question 16

A mercury switch in a float operated Low Water Fuel Cut off consists of:

A) float and Rod
B) Electrode and Transformer
C) Glass bulb, electrical contacts, small amount of mercury
D) Motorized valve
E) Diaphragm strainer and bellows assembly

Answer 16

C) Glass bulb, electrical contacts, small amount of mercury

Question 17

During monthly testing of Low Water Fuel Cut off devices, the burner should shut down when the visible level in the gauge glass is approximately:

A) Any time the level is below normal
B) 2 inches below the bottom of the Gauge Glass
C) 2.54 cm (1 inch) above the bottom of the Gauge Glass
D) Half way in the glass
E) 75 mm (3 inches)

Answer 17

C) 2.54 cm (1 inch) above the bottom of the Gauge Glass