Thermal Engineering Multiple Choice Questions on “Boiler Mountings – 1”.
1. Which of the following statements regarding boiler mountings is TRUE?
a) They ensure safe operation of the boiler
b) They are installed to increase efficiency of the boiler
c) Economizer, superheater and feed pumps are boiler mountings
d) Water level indicator is not a boiler mounting
Answer: a
Clarification: Boiler mountings are installed for safety of a boiler. Economizer, superheater and feed pumps are not boiler mountings, they are boiler accessories. Examples of boiler mountings are water level indicator, steam stop valve, man hole, pressure gauge, safety valve etc.
2. Water level indicator _____
a) indicates the amount of steam in the boiler
b) indicates the amount of water in the boiler
c) indicates the amount of water converted to steam
d) indicates the amount of steam left in the boiler
Answer: b
Clarification: Water level indicator constantly indicates the level of water inside the boiler. The water level in a boiler must not fall below a certain safe-level. If the level of water inside the boiler happens to fall below safe-level, crack and leak can occur.
3. What is the purpose of guard glass in a glass-tube water level indicator?
a) It protects the attendant, if water starts leaking
b) It protects the water gauge, if steam pressure increases the design pressure
c) It protects the attendant, if boiler cracks
d) It protects the attendant, if the gauge glass breaks
Answer: d
Clarification: The guard glass is tough. It doesn’t give shards on breaking. Guard glass covers the gauge glass. If due to sudden rush of water and steam the gauge glass breaks, the guard glass protects the attendant from getting hurt.
4. What is the purpose of pressure gauge?
a) It measures the pressure exerted on the boiler shell from outside
b) It measure the current atmospheric pressure
c) It measures pressure exerted inside the boiler shell
d) It measures hydrostatic pressure of water at the bottom of the boiler shell
Answer: c
Clarification: Pressure gauge measures the pressure exerted inside the boiler shell. Normally, it is manufactured to indicate pressure upto double the maximum working pressure. It measures gauge pressure i.e. pressure above atmospheric pressure.
5. Which of the following statements about compound pressure gauge is TRUE?
a) It measure the hydrostatic pressure exerted by water at the bottom surface
b) It can measure pressures above and below atmospheric pressure on the same dial
c) It is installed at the bottom of the boiler shell
d) It measures absolute pressure
Answer: b
Clarification: A compound pressure gauge is designed such that it can measure pressures above and below atmospheric pressure. It is a pressure gauge, hence mounted on the front top of the shell.
6. The syphon tube in the Bourdon pressure gauge (single tube) is filled with _____
a) mercury
b) turpentine oil
c) mineral water
d) condensed water
Answer: d
Clarification: Syphon tube is an integral part of the Bourdon pressure gauge. The syphon tube is completely filled with condensed water. Steam pressurizes the water in the syphon from one side and the water is forced into the elliptical tube.
7. Which of the following statements about Bourdon pressure gauge is FALSE?
a) Double-tube Bourdon gauge is more rigid than the single tube
b) Double-tube Bourdon gauge is more suitable for portable boilers
c) It measures the gauge pressure
d) The movement of the free end of the elliptical tube is proportional to the internal pressure of the boiler
Answer: d
Clarification: The movement of the free end of the elliptical tube is proportional to the difference between internal and external pressure in the tube. Since the external pressure is atmospheric the free end measures gauge pressure.
8. The function of a safety valve is _____
a) to release the excess steam when the steam pressure exceeds the rated pressure
b) to extinguish fire when the temperature reaches impermissible value
c) to release the excess water
d) it cuts off the water supply when water level reaches its maximum limit
