Upgrade to remove ads
Only $2.99/month

Power Engineering 4th Class Ch 105

Terms in this set (25)

c
A hot water boiler operating control can be a pressure switch:
Choose one answer.
a. That is normally open
b. That is sensitive to the expansion and contraction of boiler water
c. Utilizing a closed liquid filled system
d. That is sensitive to system steam pressure
e. That is sensitive to boiler steam pressure
e
The type of combustion control frequently used on a small packaged boiler is
Choose one answer.
a. a semi-automatic control
b. a modulating control
c. a proportional control
d. a constant pressure control
e. an on-off control
c
A modulating control steam heating boiler:
Choose one answer.
a. Is always fully automatic
b. Will have a narrow operating pressure range
c. Maintains a steady boiler pressure
d. Will have a constant combustion air, flow rate
e. Cannot be adjusted
c
Prior to a boiler safety valve popping during routine boiler operation:
Choose one answer.
a. A try lever test should be performed
b. The pressure gage should be checked
c. The high limit switch should open
d. The feedwater pump should stop
e. The high level alarm should sound
a
An operating control switch for an ON-OFF boiler:
Choose one answer.
a. Uses a differential spring to reduce cycling
b. Can only have its cut-in setting adjusted
c. Has an un-adjustable span between cut-in and cut-out
d. Utilizes a resistance coil
e. Operates in conjunction with a Modutrol motor
b
The most important fitting installed between the operating switch of a steam boiler and the boiler itself is a
Choose one answer.
a. Tee with a plug
b. Syphon
c. Blowdown valve
d. Test connection for an inspector
e. Pressure gage
b
On a cluster burner, the high fire nozzle will:
Choose one answer.
a. Be in operation on start-up.
b. Operate continuously when steam demand exceeds boiler capacity.
c. Be ignited by a pilot flame.
d. Operate regardless of where the manual over-ride switch is set.
e. Respond to electrical resistance
c
What is the purpose of the high limit control on a hot water boiler?
Choose one answer.
a. To stop the boiler if the water level control fails.
b. To act as a emergency stop for the operator
c. To shut down the burner if the water temperature exceeds 121 deg C.
d. To prevent the pressure in the boiler rising above 210 kPa gage.
e. To prevent excessive pressure from developing
a
The main steam boiler control device used with an on/off combustion fuel control is a _____ sensing element.
Choose one answer.
a. Pressure
b. Level
c. Temperature
d. Flow
e. Pneumatic
a
A flame control switch:
Choose one answer.
a. Varies electrical current to a modutrol motor
b. Will start and stop a boiler
c. Cannot have its settings adjusted
d. Will not result in simultaneous adjustment of air and fuel
e. Eliminates the need for a high limit control
a
A test lead or "jumper wire" is required when testing:
Choose one answer.
a. High steam pressure or high water temperature limit controls
b. A high gas pressure fuel cut-off switch
c. A safety valve with the test lever
d. The low water fuel cut-off switch
e. A low gas pressure fuel cut-off
e
A high gas pressure fuel cut-off switch:
Choose one answer.
a. Closes when gas pressure is too high
b. Automatically resets itself when the gas pressure is restored
c. Is located upstream of the automatic fuel valve
d. Is a normally open switch
e. Prevents excessive fuel pressure from creating an unstable flame condition
b
An ON-OFF steam boiler:
Choose one answer.
a. Will maintain a fairly constant steam pressure
b. Operates most efficiently at continuous firing
c. Will cycle on and off based on temperature
d. Must have a low capacity
e. Cannot operate in a multi-boiler system
b
Modulating combustion controls
Choose one answer.
a. Regulate the steam and feedwater flow
b. Regulate the fuel and air flow
c. Control the atomizing air
d. Control the combustion programmer
e. Control the draft and feedwater temperature
d
Quickly closing the main burner manual cock valve during boiler operation should trip the:
Choose one answer.
a. Flame scanner
b. Combustion air proving switch
c. Low gas pressure fuel cut-off
d. High gas pressure fuel cut-off
e. Low fire interlock switch
d
A manual "high-low" switch should be switched to "high" or "auto":
Choose one answer.
a. As soon as the main flame has stabilized
b. Prior to ignition of the main flame
c. When pressure is too low
d. When the boiler has been properly warmed up
e. During boiler pre-purge
e
A levelling indicator is found on

a) the casing of a heating boiler
b) a low-water fuel cutoff switch
c) a boiler feedwater pump
d) a modutrol motor
e) an ON-OFF operating control switch
a
A resistance control or "potentiometer" for modulating
control

a) works in conjunction with a modutrol motor
b) utilizes a mercury switch
c) senses steam temperature
d) can only be used on a fully automatic boiler
e) can operate only in the vertical position
a
A potentiometer control

a) varies electrical current to a modutrol motor
b) will start and stop a boiler
c) cannot have its settings adjusted
d) eliminates the need for a high limit control
e) will not result in simultaneous adjustment of air and
fuel
e
A high limit control switch

a) is necessary on all boilers
b) activates after the safety valve opens
c) is a normally open switch
d) usually does not require manual resetting
e) must be used when a boiler is not under continuous
supervision
b
A thermal element is

a) used to measure pressure
b) capable of sensing temperature and converting it to a
pressure signal
c) a type of open system
d) used to measure heat content
e) commonly termed an "aquastat"
b
An aquastat

a) senses water level
b) is like a thermal element without a capillary tube
c) can be located away from its point of measurement
d) measures water flow
e) is a modulating device
e
A low fire switch

a) is a type of manual over-ride
b) takes no part in the start-up of an automatic boiler
c) is a normally closed switch
d) utilizes a thermal element for its operation
e) acts as an interlock to ensure minimum damper setting
c
Combustion air safety switches are commonly found

a) on natural draft boilers
b) on hot water boilers only
c) on boilers utilizing a forced draft fan
d) on gas fired boilers only
e) as noninterlocking devices and take no part in a startup
e
The combustion air proving switch

a) should be checked when air flow is minimum
b) should not be checked while the boiler is in the purge
cycle of start-up
c) is a normally closed switch
d) must always be a manual reset device
e) should be checked when air flow is maximum
THIS SET IS OFTEN IN FOLDERS WITH...