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
Two conditions which may occur during warm-up of a cold boiler are smoking and:
A.Pressure pulsations
B.Flue gas condensation
C.Fuel flow surging
D.Flame pulsations
E.Very high stack temperatures
b
Uneven thermal expansion in a firetube boiler occurs between the:
1. Fire tubes
2. Water tubes
3. Furnace
4. Drum
5. Shell
A.1, 3, 5
B.3, 4, 5
C.1, 2, 4
D.1, 2, 3
E.2, 3, 4
a
The most important rule in the safe operation of steam boilers is to:
A.Keep water in the boiler at the proper level
B.Keep the feedwater chemical free
C.Blowdown the gage glass regularly
D.Keep the boiler pressure below the safety valve setting
E.Add chemicals to the boiler feedwater
a
The operating pressure of low-pressure hot water heating boilers varies considerably, it is recommended that the differential between the safety relief valve set pressure and the boiler operating pressure is kept to a minimum of _____ or 25% of the relief valve setting, whichever is greater.
A.15 psi. (100 kPa)
B.69 kPa (10 psi)
C.6 psi. (40 kPa)
D.100 psi. (700 kPa)
E.3 psi. (20 kPa)
b
When a cold oil-fired boiler is started up, the operator may notice that during the first part of the warm-up period the stack will smoke slightly due to:
A.The incorrect gas/air ratio
B.Using the wrong oil
C.The incorrect gas/oil ratio
D.The oil not being pre heated
E.The furnace temperature not being high enough to vaporize the incoming fuel oil immediately and completely
e
A hot water heating system automatic fill valve will:
A.Prevent the boiler from tripping on low water level
B.Keep the chemical tanks filled
C.Maintain system pressure, regardless of level
D.Maintain boiler water level at some predetermined value
E.Sense expansion tank level
c
The two conditions that may occur during the warm-up period which may seem to be abnormal to the operator but will disappear after the boiler heats up are:
1. Smoking
2. Water hammer
3. Condensation
4. Corrosion
A.1, 3
B.1, 2
C.1, 4
D.2, 3
E.2, 4
a
Heavy soot build-up can affect combustion conditions in the furnace and may result in:
A.A boiler low water condition
B.A furnace flame out
C.A furnace explosion
D.Increased sludge and scale formation
E.Loss of ignition
c
During the filling of an empty boiler, a valve that should be open to allow the air to escape is the:
A.Boiler vent valve
B.Gauge glass drain valve
C.Boiler stop valve
D.Boiler drain valve
E.Gauge glass steam valve
a
When a steam boiler has to be taken out of service give it a good blowdown to remove as much sediment as possible stop when the drain runs clear. Refill the boiler to the top of the glass maintaining the boiler water temperature above _____ for about one hour to release all the dissolved gases.
A.50°C (98°F)
B.85°C (185°F)
C.121°C (250°F)
D.120°C (248°F)
E.77°C (170°F)
b
a hot water heating system automatic fill valve will
a. sense expansion tank level
b. maintain system pressure, regardless of level
c. maintain boiler water level at some predetermined value
d. prevent the boiler from tripping onlow water level
b
prior to starting a new boiler for the first time, it is common practice to
a. establish a main flame first to ensure the controls funtion properly
b. ensure all controls work before contacting an inspector
c. “boil out” the waterside with chemicals to remove oil, etc..
d. test the safety or relief valve first
c
boiler stack temp is rising due to soot build up on the boiler tubes. this could:
a. result in condensation forming in the flue gas system
b. cause the water level to drop to the trip level
c. cause foaming of the boiler water
d. cause a furace explosion
d
when doing routine checks on a hot water system, one thing that is often overlooked is
a. system pressure
b. expansion tank level
c. unusual noise
d. fuel pressure
c
two conditions that may occur during warm up of a cold boiler are smoking and:
a. fuel slow surging
b. flame pulsations
c. very high stack temp
d. flue gas condensation
d
a boiler item that should be checked monthly is
a. refractory
b. fireside cleanliness
c. the flame detection system
d. water outlet temp
c
if maintanence is planned for a hot water boiler it should be drained
a. only after its cooled down
b.as soon as possible after removal from service
c. wuth the vent valve closed
d. while using cold feedwater to cool it
a
a hot water boiler should be equipped with water supply and return valves so that
a. it can be drained without draining the system
b. it cannot be isolated from the system
c. the system can be drained through the boiler
d. boiler pressure will not be appied to the system
a
during the filling of an empty boiler, a valve that should be open to allow the air to escape the
a. gauge glass steam valve
b. boiler drain valve
c. boiler vent valve
d. gauge glass drain valve
c
which of the following is done to prevent excessive stresses of the boiler metal due to uneven expansion
a. warm a boiler up as quickly as possible
b. open the safety valve slowly during test
b. warm boiler up before filling it with water
c. warm boiler up as slowly as possible
d
if boiler level has dropped below the gauge glass during boiler operation the operator is to
a.contact boiler inspector immediatly
b. shut down, cool and then inspect the boiler for damage before refilling
c. immediatly restore water level before shutting off the unit
d. open the blow down valves in order to have the low water fuel cut off trip the unit
b
some of the reasons why heating boiler accidents occur are
a. the misconception that no supervision is required for automatically fired boilers
b. the inexpirience or lack of training of operatting personal
c. inadequate maintenance of boilers and controls
d. all of the above
d
the most important factor to be considered during steam boiler operation is
a. housekeeping
b. water level
c. steam pressure
d. combustion quality
b
when removing a steam boiler from service, the vent valve should be opened at 15-20 kPa to
a. permit draining of the boiler while it is still hot
b. let the O2 within the boiler escape
c. maintain the boiler water level at operating level
d. prevent a vacuum from forming in the boiler
d
