Book 1 Chapter 9: Boiler Combustion Controls Flashcards
What is the voltage level generated by a thermocouple?
A) 30 milivolts
B) 15 milivolts
C) 60 milivolts
D) 100 milivolts
A) 30 milivolts
What is the maximum allowable water temperature in a hot water boiler?
A) 200C (392F)
B) 75C (167F)
C) 150C (302F)
D) 120C (248F)
D) 75C (167F)
What is the maximum time allowed for a gas valve to close following a flame failure on a gas burner with an electronic flame scanner?
A) 5 seconds
B) 2 seconds
C) 4 seconds
D) 10 seconds
C) 4 seconds
The time taken for the automatic pilot valve to close in the event of a loss of flame detection is about:
A) 5 seconds
B) 10 seconds
C) 15 seconds
D) 22 seconds
B) 10 seconds
The programming control relay of a flame safeguard device:
A) Should occasionally have the dust blown out of it
B) Requires yearly maintenance tune up by the operator
C) Can be bypassed
D) Requires an adjustment check monthly by the chief engineer
E) Needs an electrician to work on it
A) Should occasionally have the dust blown out of it
The flame scanner lens is:
A) Concave
B) Concentric
C) Cleanable
D) Easily changeable
E) Inaccessible
C) Cleanable
The flame scanner:
A) All of the above
B) Should be shielded from light
C) Is not sensitive to electromagnetic radiation
D) Should be cool enough to hold in the hand during operation
E) Must be protected from drafts
D) Should be cool enough to hold in the hand during operation
One type of flame failure device uses a lead sulphide cell that is sensitive to:
A) The colour of the fuel
B) Infrared rays
C) Ultraviolet rays
D) Temperature
E) Radio waves
B) Infrared rays
The fuel to a boiler burner should be shut off immediately if it fails to ignite in order to;
A) Prevent spills
B) Save power
C) Prevent boiler corrosion
D) Save fuel
E) Prevent furnace explosion
E) Prevent furnace explosion
A thermocouple:
A) Senses changes in air pressure
B) Consists of two similar wires
C) Senses infrared light from the flame
D) Produces an electrical signal
E) Senses changes in fuel pressure
D) Produces an electric signal
Thermocouples are connected in series to:
A) Increase the sensitivity of the detection system
B) Generate a lower voltage
C) Generate a higher voltage
D) Monitor more than one flame source
E) Provide a spare thermocouple in case one fails
C) Generate a higher voltage
The flame scanner sight tube:
A) Should be shielded from the burner radiation
B) Should be lubricated often
C) Should be aimed at the rear of the furnace
D) Should be free of obstructions
E) Is filled with protective packing
D) Should be free of obstructions
Flame Rods:
A) Are rarely used as they are unreliable and require frequent maintenance
B) Should not be exposed to temperatures above 100C
C) Require frequent filing of electrical contacts to prevent corrosion of the device
D) Are commonly used with oil-fired burners
E) Should shut off the fuel within four seconds of flame failure
E) Should shut off the fuel within four seconds of flame failure
A flame rod:
A) Senses the temperature of the flame
B) Is used for gas and oil fired burners
C) Forms an electric circuit with the rod, flame and relay
D) Forms an electric circuit with rod, flame and burner
E) Is used to light the main burner
D) Forms an electric circuit with rod, flame and burner
The flame Rod Boiler Flame Failure is commonly only used with:
A) Gas burners
B) Electric heaters
C) Coal burners
D) Solid fuels
E) Oil burners
A) Gas burners
A photoelectric cell reacts to the _____ emitted by the flame
1. Ultraviolet rays
2. Thermocouple
3. Flame rods
4. Infrared rays
A) 1,2
B) 2,4
C) 1,4
D) 2,3
E) 1,3
C) 1,4
The infrared scanner contains a _____ cell which reacts to infrared rays.
A) Lead sulphide
B) Sodium sulphide
C) Lead sulphate
D) Lithium bromide
E) Sodium chloride
A) Lead sulphide
The voltage supply generated by the thermocouples is usually not more than:
A) 100 millivolts
B) 15 millivolts
C) 30 millivolts
D) 0 millivolts
E) 50 millivolts
C) 30 millivolts
In an oil fired boiler the fuel enters the furnace in a ______ state mixes with combustion air and is ignited.
A) Vaporized
B) Mixed
C) Solid
D) Gaseous
E) Liquid
A) Vaporized
This scanner is mounted as close to the flame as physically possible without subjecting it to a temperature over:
A) 50C (98F)
B) 75C (167F)
C) 120C (248F)
D) 150C (302F)
E) 100C (212F)
E) 100C (212F)
The flame rod method of sensing is often referred to as:
A) Infrared detection
B) Flame rectification
C) Ultraviolet detection
D) Photoelectric scanning
E) The ionized particle principle
B) Flame rectification
Unburned fuel collecting in the furnace can mix with the combustion air and may ignite, causing a:
A) Boiler drum failure
B) Serious explosion
C) Spike in steam production
D) Fire tube failure
E) Water tube explosion
B) Serious explosion
If for any reason, the burner should go out during normal operation, or the fuel should fail to ignite during startup:
A) Increase the combustion air flow
B) Increase the fuel flow
C) The air to the burner must be shut off immediately
D) The fuel to the burner must be shut off immediately
E) No action is required
D) The fuel to the burner must be shut off immediately
The most commonly used flame detection devices are:
1.Ultraviolet detectors
2. Thermocouples
3. Flame rods
4. Infrared detectors
5. Photoelectric cells
A) 1,2,4
B) 2,3,5
C) 3,4,5
D) 2,3,4
E) 1,2,3
B) 2,3,5
In a gas fired boiler the fuel enters the furnace in a _____ state mixes with combustion air and is ignited.
A) Liquid
B) Vaporized
C) Solid
D) Gaseous
E) Mixed
D) Gaseous
