Power Engineering 4th Class unit B 3
chapter 1 Questions and answers well
explained
What is the minimum number of safety valves required on a boiler that has a heating
surface of 42 m2?
a. None
A
b. One
c. Two
VI
d. Three
e. Four - ANS B
TU
The safety valves on a boiler and are set to open at 1380 kPa. What is the maximum
permissible pressure rise in the boiler if it is fired at full capacity with the steam outlet
valve closed?
a. 0 kPa
IS
b. 37.5 kPa
c. 41.4 kPa
d. 69 kPa
OM
e. 82.8 kPa - ANS E
The blowdown on a safety valve is adjusted by turning the:
a. Inspector's seal
b. Valve disc
NA
c. Adjusting nut
d. Adjusting ring
e. Valve seat - ANS D
JP
If the safety valves on a boiler are undersized, the boiler pressure may:
a. Rise 5% above the maximum allowable working pressure MAWP
b. Not rise more than 15% above the MAWP
c. Remain at the MAWP
d. Rise to 6% above the MAWP
e. Rise more than 6% above the MAWP - ANS E
Safety valves "pop" open because the pressure of the steam:
a. Acts upon a blow down ring
, b. Acts upon a huddling chamber
c. Acts upon a larger area as soon as the valve opens
d. Increases due to the discharge ports
e. Decreases the force created by the spring - ANS C
If a boiler was fired with the main steam stop valve closed, the safety valves should
ensure that the:
a. Pressure cannot exceed the maximum working pressure by more than 6%.
b. Water glass will not burst with the pressure.
c. Fuel cut-off will operate.
A
d. Pressure cannot exceed the maximum working pressure by more than 3%.
e. Pressure is never more than the hydrostatic test pressure. - ANS A
VI
Testing a safety valve on a boiler by pulling the try-lever
a. Ensures the popping pressure is correct
TU
b. Indicates that valve capacity is adequate
c. Ensures the closing pressure is correct
d. Takes approximately two seconds
e. Ensures the valve is free to operate - ANS E
IS
If a boiler has only one safety valve, its heating surface must not exceed
a. 75 m2
OM
b. 47 m2
c. 36 m2
d. 28 m2
e. 19 m2 - ANS B
NA
The purpose of the spring in a safety valve is to:
a. Help open the testing lever
b. Pull open the valve at blowing pressure
c. Adjust the pressure setting of the valve
d. Adjust the blow down of the valve
JP
e. Hold down the disc on the seat - ANS E
The test lever on a safety valve must not be used unless the boiler:
a. Is at maximum operating pressure
b. Has no load on it
c. Inspector approves it
d. Pressure is at least 75% of the valve popping pressure
e. Is at the popping pressure of the safety valve - ANS D
chapter 1 Questions and answers well
explained
What is the minimum number of safety valves required on a boiler that has a heating
surface of 42 m2?
a. None
A
b. One
c. Two
VI
d. Three
e. Four - ANS B
TU
The safety valves on a boiler and are set to open at 1380 kPa. What is the maximum
permissible pressure rise in the boiler if it is fired at full capacity with the steam outlet
valve closed?
a. 0 kPa
IS
b. 37.5 kPa
c. 41.4 kPa
d. 69 kPa
OM
e. 82.8 kPa - ANS E
The blowdown on a safety valve is adjusted by turning the:
a. Inspector's seal
b. Valve disc
NA
c. Adjusting nut
d. Adjusting ring
e. Valve seat - ANS D
JP
If the safety valves on a boiler are undersized, the boiler pressure may:
a. Rise 5% above the maximum allowable working pressure MAWP
b. Not rise more than 15% above the MAWP
c. Remain at the MAWP
d. Rise to 6% above the MAWP
e. Rise more than 6% above the MAWP - ANS E
Safety valves "pop" open because the pressure of the steam:
a. Acts upon a blow down ring
, b. Acts upon a huddling chamber
c. Acts upon a larger area as soon as the valve opens
d. Increases due to the discharge ports
e. Decreases the force created by the spring - ANS C
If a boiler was fired with the main steam stop valve closed, the safety valves should
ensure that the:
a. Pressure cannot exceed the maximum working pressure by more than 6%.
b. Water glass will not burst with the pressure.
c. Fuel cut-off will operate.
A
d. Pressure cannot exceed the maximum working pressure by more than 3%.
e. Pressure is never more than the hydrostatic test pressure. - ANS A
VI
Testing a safety valve on a boiler by pulling the try-lever
a. Ensures the popping pressure is correct
TU
b. Indicates that valve capacity is adequate
c. Ensures the closing pressure is correct
d. Takes approximately two seconds
e. Ensures the valve is free to operate - ANS E
IS
If a boiler has only one safety valve, its heating surface must not exceed
a. 75 m2
OM
b. 47 m2
c. 36 m2
d. 28 m2
e. 19 m2 - ANS B
NA
The purpose of the spring in a safety valve is to:
a. Help open the testing lever
b. Pull open the valve at blowing pressure
c. Adjust the pressure setting of the valve
d. Adjust the blow down of the valve
JP
e. Hold down the disc on the seat - ANS E
The test lever on a safety valve must not be used unless the boiler:
a. Is at maximum operating pressure
b. Has no load on it
c. Inspector approves it
d. Pressure is at least 75% of the valve popping pressure
e. Is at the popping pressure of the safety valve - ANS D
