chapter 11 Flashcards
Why is it important to warm a steam boiler up slowly?
a. So that the operating controls have time to come online
b. So that proper water circulation is established before going to high fire
c. So that the flue gases will be hot before going to high fire
d. So that the boiler water expands properly before going to high fire
b
A furnace explosion can be caused by:
a. Failure of the safety valve
b. Operating with steam stop valves closed
c. Rupture of the boiler shell
d. An accumulation of combustible gases
d
When preparing a boiler with high-fire low fire burner control for start-up, how should the control switch be set
a. on high fire position
b. on constant fire position
c. on modulating manual position
d. on low fire position
d
A sudden drop in boiler steam pressure without a corresponding drop in boiler water temperature could result in:
a. water hammer
b. boiler implosion
c. boiler explosion
d. cavitation
c
The boiler vent is open when warming up a boiler until:
a. Main steam valves are opened
b. There is 2 - 3 psi/ 15 -20 kPa of steam pressure on the boiler
c. The boiler has been steaming for at least 24 hours
d. The water level is visible at the lowest part of the gauge glass
b
Where do you initially bring the water level to when refilling a hot water heating boiler that has drained for service
a. To half-glass in the expansion valve
b. Until water escapes the open vent
c. ill until system pressure is minimum 85 kPa (12 psi)
d. To slightly below the normal operating water line so there is room for expansion when you heat the boiler up
b
A watertube boiler is more susceptible to expansion stresses than the firetube boiler
True False
false
Thermal shock produces
a. Strong internal stresses in the boiler metal
b. A series of sharp hammer-like blows in the boiler metal
c. A sudden vapour-cavity formation, growth and subsequent collapse in a saturated liquid
d. All of the above
a
It is recommended that a hot water heat boiler fitted with a safety relief valve that has a 207 kPa (30 psi) set pressure should have an operating pressure no greater than:
a. 207 kPa (30 psi)
b. 138 kPa (20 psi)
c. 1100 kPa (160 psi)
d. 103 kPa (15 psi)
b
When blowing down a boiler equipped with a quick opening valve and a slow opening valve, the quick opening valve is:
a. A plug valve
b. Opened first and closed last
c. A globe valve
d. Opened last and closed first
b
Where do you initially bring the water level to when refilling a hot water heating boiler that has drained for service
a) Fill until system pressure is minimum 85 kPa (12 psi)
b) Until water escapes the open vent
c) To slightly below the normal operating water line so there is room for expansion when you heat the boiler up
d) To half-glass in the expansion valve
b
Thermal shock produces
a) A series of sharp hammer-like blows
b) A sudden vapour-cavity formation, growth and subsequent collapse in a saturated liquid
c) All of the above
d) Strong internal stresses in the boiler metal
d
When preparing a hot water heating boiler that is cool and has been offline for some time to go back online in a multi-boiler plant where other boilers are already online:
a) Keep the stop and return valves on the cool boiler closed until it is up to temperature, then open the valves slowly
b) Prior to firing the cool boiler, slowly open the stop and return valves introduce heat to it, then fire the boiler when it is up to plant temperature
c) Slowly open the return valve on the cool boiler and leave the stop valve closed, fire the boiler slowly to bring it to temperature, then open the stop valve slowly
d) Any of these methods are acceptable
a
In a hot water heating boiler, it’s possible for the expansion tank level to be normal even though the upper floors of the system lack water
True False
true
In a low pressure steam boiler the maximum operating pressure should be:
a) 50 kPa (7 psi) lower than the safety valve setting
b) 103 kPa (15 psi)
c) 69 - 90 kPa (10 - 13 psi)
B