BCIT Exam 2 | Questions with Correct Verified
Answers
5
The float mechanism of the feeder is mounted directly in the tank. The disadvantage of this
arrangement is obvious. The water level in a condensate receiver can be subjected to
violent fluctuations due to the return of the condensate in slugs which will affect the float
control, resulting in a very unsteady valve operation.
With some condensate receivers, the makeup water valve is operated by a float located inside the
receiver. A disadvantage to this arrangement is
1) the operating arm for the float is too long.
2) the float tends to get hung up.
3) level control is affected by pressure in the receiver.
4) the makeup valve tends to scale up.
5) the water level in the receiver can fluctuate radically resulting in unsteady valve operation.
4
The purpose of the bellows in a float operated low water cutoff using a mercury switch is to
,1) operate the snap switch that shuts off the fuel supply.
2) sense the water level in the boiler.
3) open the circuit and shut off the fuel if a low water condition occurs.
4) seal between the mercury switch and float chamber.
5) keep sediment from entering the float chamber.
3
When a boiler shuts down due to a low-water condition
1) a manual reset switch must be used.
2) a prepurge will not be necessary.
3) level must be restored to above the cutoff line before the unit can be restarted.
4) it can be restarted by simply resetting the cutoff switch.
5) the feed water flow will also stop.
1
,In heating plants with multiple boilers that are supplied from a single condensate receiver the
level is controlled in each boiler by separate feed water valves supplied from a common header.
1) True
2) False
3
In multiple boiler heating plants, the control of the water level in each boiler is independent
from the other boilers but the feed water is usually supplied through a common feed line by
a single pump.
In heating plants with multiple boilers that are supplied from a single condensate receiver, all
boilers commonly share a single
1) drum level control valve.
2) water column and gage glass.
3) boiler feed pump.
4) low water fuel cutoff.
5) burner.
, 1
A hot water boiler control is often used on smaller capacity boilers. This control has on-off
action and is commonly known as an aquastat. Its sensing bulb is directly connected to the
bellows (no capillary tube) which makes it necessary to mount the control at the point
where the water temperature is sensed. Although different in design, the aquastat controls
the burner circuit in the same manner as the control described previously.
An aquastat, used on hot water boilers,
1) is a thermal element without a capillary tube.
2) senses water level.
3) measures water flow.
4) is a modulating device.
5) can be located away from its point of measurement.
4
Hot water boilers are equipped with operating controls similar in construction and
application to the operating controls used on steam boilers except that the bellows of these
controls are not actuated by steam pressure but by pressure fluctuations caused by
expansion and contraction of a liquid in a thermal element due to increases or decreases in
the water temperature.
Answers
5
The float mechanism of the feeder is mounted directly in the tank. The disadvantage of this
arrangement is obvious. The water level in a condensate receiver can be subjected to
violent fluctuations due to the return of the condensate in slugs which will affect the float
control, resulting in a very unsteady valve operation.
With some condensate receivers, the makeup water valve is operated by a float located inside the
receiver. A disadvantage to this arrangement is
1) the operating arm for the float is too long.
2) the float tends to get hung up.
3) level control is affected by pressure in the receiver.
4) the makeup valve tends to scale up.
5) the water level in the receiver can fluctuate radically resulting in unsteady valve operation.
4
The purpose of the bellows in a float operated low water cutoff using a mercury switch is to
,1) operate the snap switch that shuts off the fuel supply.
2) sense the water level in the boiler.
3) open the circuit and shut off the fuel if a low water condition occurs.
4) seal between the mercury switch and float chamber.
5) keep sediment from entering the float chamber.
3
When a boiler shuts down due to a low-water condition
1) a manual reset switch must be used.
2) a prepurge will not be necessary.
3) level must be restored to above the cutoff line before the unit can be restarted.
4) it can be restarted by simply resetting the cutoff switch.
5) the feed water flow will also stop.
1
,In heating plants with multiple boilers that are supplied from a single condensate receiver the
level is controlled in each boiler by separate feed water valves supplied from a common header.
1) True
2) False
3
In multiple boiler heating plants, the control of the water level in each boiler is independent
from the other boilers but the feed water is usually supplied through a common feed line by
a single pump.
In heating plants with multiple boilers that are supplied from a single condensate receiver, all
boilers commonly share a single
1) drum level control valve.
2) water column and gage glass.
3) boiler feed pump.
4) low water fuel cutoff.
5) burner.
, 1
A hot water boiler control is often used on smaller capacity boilers. This control has on-off
action and is commonly known as an aquastat. Its sensing bulb is directly connected to the
bellows (no capillary tube) which makes it necessary to mount the control at the point
where the water temperature is sensed. Although different in design, the aquastat controls
the burner circuit in the same manner as the control described previously.
An aquastat, used on hot water boilers,
1) is a thermal element without a capillary tube.
2) senses water level.
3) measures water flow.
4) is a modulating device.
5) can be located away from its point of measurement.
4
Hot water boilers are equipped with operating controls similar in construction and
application to the operating controls used on steam boilers except that the bellows of these
controls are not actuated by steam pressure but by pressure fluctuations caused by
expansion and contraction of a liquid in a thermal element due to increases or decreases in
the water temperature.
