CH.86
A bimetal thermostat reacts to changes of:
A )
pressure
B )
flow
C )
humidity
D )
heat
E ) temperature
A strain gage is used to measure:
A )
stresses in pipe walls
B )
pressure in boilers
C ) levels in tanks
D )
the densities of materials
E )
the tension given by a compressive load
When differential pressure manometers are
used the external leg is often called the _____________ or constant head.
A )
liquid
B )
variable
C )
water
D ) reference
E )
average
Relative to flow, velocity is kinetic
energy and when velocity increases, the:
A )
pressure and potential energy, will also increase
B )
cross-sectional area of the piping will be increased
C )
the mass quantity flowing per second will decrease
D ) potential energy in the
form of pressure will decrease
E )
density will decrease
One of the most widely used process
variables in a system is:
A )
temperature
B )
pressure
C )
density
D )
purity
E ) flow
The electrical output from a thermocouple
is measured by a:
A )
milliampmeter
B )
wattmeter
C )
milliwattmeter
D ) millivoltmeter
E )
power meter
A chromatograph uses electronic devices
which:
A )
utilise electrical current as a measurement base
B ) have inverse resistance
properties relative to temperature
C )
increase in resistance as temperature rises
D )
work in conjunction with a thermocouple
E )
are made of chromel and alumel
Temperatures are measured by:
A )
wattmeters
B )
bourdon tubes
C )
thermowells
D )
pressure differential
E ) thermocouples
A thermocouple will produce a DC
millivoltage which:
A )
will be read on a pressure scale
B )
will be fully proportional to a temperature difference
C )
increases as temperature decreases
D ) is not quite proportional
to temperature differences
E )
varies inversely with temperature
The purpose of a spiral or a helix Bourdon
tube is:
A )
to increase the pressure rating
B ) to provide a greater
degree of rotation
C )
to decrease the degree of rotation
D )
to decrease the linear motion
E )
to reduce fluttering of the indicator needle
CH.87
The nozzle receives a constant air supply
pressure of approximately:
A )
140 psi
B )
20 kPa
C ) 140 kPa
D )
210 kPa
E )
30 kPa
A sensing element sends its signal to a
fan:
A ) transmitter
B )
sender
C )
conveyer
D )
express
E )
recorder
A flapper-nozzle assembly is basic to all:
A )
controllers
B ) transmitters
C )
recorders
D )
pneumatic devices
E )
actuators
When controller output is proportional to
the amount of deviation, the controller is:
A )
derivative only
B ) integral
C )
two-position
D )
proportion plus reset plus rate
E ) proportional
A valve which has two seats, gives good
throttling action, but does not seat well is a:
A ) double-seated valve
B )
reverse-acting valve
C )
reverse-seated valve
D )
single-seated valve
E )
direct-acting valve
A valve that seals on the downstroke is:
A )
reverse-acting
B )
single sealed
C ) direct-acting
D )
double sealed
E )
uni-directional
In an automatic control system the
controller output manipulates the:
A )
transmitter
B )
sensing element
C )
recorder
D ) control valve
E )
thermocouple
A recorder utilising a spiral Bourdon tube
will have a pen movement:
A )
linear to the tube travel
B ) proportional to the change
in tube pressure
C )
angular to the tube travel
D )
range of 0 to 24 hours
E )
range of 0 to 7 days
A valve actuator:
A )
cannot be reverse acting
B )
will always have one side of the diaphragm open to atmosphere
C )
is a two-position device
D ) position is a function of
controller output
E )
causes a valve to always fail open
Most solenoid valves are unlike globe
valves in that upstream line pressure will:
A )
act to open the valve
B )
be less than downstream pressure
C )
be sensed by a transmitter
D ) act to close the valve
E )
pass through a restriction or nozzle
CH.88
Lead sulphide cells operate when __________
is present.
A )
no light
B ) infrared
C )
heat
D )
ultra-violet light
E )
flue gas
A packaged steam boiler modulating
combustion control system will routinely:
A )
maintain drum level within a desired range
B )
maintain flue gas temperature at some set point
C )
alter fuel flow without changing the air flow
D )
satisfy all load demands regardless of capacity
E ) maintain boiler steam
pressure within a desired range
A slight drop in steam pressure causes a
sudden increase of water volume in the steam drum and it is known as:
A )
rise
B )
water increase
C )
thermo-increase
D )
growth
E ) swell
The second element of a two element
feedwater control system compensates for or offsets:
A )
level variation
B )
differential feedwater pressure
C )
differential steam flow rate
D )
feedwater temperature variation
E ) shrink and swell
Modulating burner controls operate by
regulating:
A )
steam flow and fuel flow
B )
fuel temperature and air flow
C )
fuel flow, air flow, and feedwater pressure
D ) fuel flow and air flow
E )
fuel flow and atomising steam flow
On a packaged boiler a number of electrical
switches connected in series can be categorized as:
A )
controls
B ) interlocks
C )
start-up devices
D )
programmer controls
E )
detectors
Modulating combustion control on a heating
boiler is accomplished by:
A )
shutting down or lighting up the burner as pressure or temperature rises
or falls
B )
regulating the air flow to control combustion
C ) changing the amount of
fuel and air to the burner
D )
opening or closing the forced draft damper
E )
regulating the fuel and feedwater flow
Which of the following is a flame sensing
device?
A )
thermopile
B )
heat sensing control
C )
stack relay
D )
cut-off valve
E ) scanner
A lead sulphide cell is sensitive to IR
rays and:
A ) its resistance to current
flow varies inversely with ray emissions
B )
its resistance to current does not change during operation
C )
will not sense steady IR rays, only pulsating ones
D )
will not respond to glowing hot refractory
E )
must be replaced at least monthly
Two element feedwater control:
A ) measures water level and
steam flow
B )
compares forced draft to water level
C )
compares fuel flow to steam flow
D )
has one element in the feed control valve and one element in the
deaerator
E )
compares water level to the firing rate
CH.89
An interrupted pilot of an automatic
boiler:
A )
burns continuously, like that in a home furnace
B )
lights before the main burner and goes out with it
C )
is one which has been extinguished by a flame scanner
D ) lights, completes a trial,
and extinguishes after a main flame trial
Automatic boiler programming controls:
A )
must incorporate a modulating control system
B )
do not require interlocking devices
C ) require an ON-OFF or
two-position control switch
D )
cannot make use of high-low fire control
E )
are not interconnected with the water level control system
With automatic fuel fired boiler programmed
control the normal firing period begins approximately:
A )
44 seconds after FD fan starts
B )
75 seconds after FD fan starts
C ) 60 seconds after FD fan
starts
D )
10 seconds after pilot extinguishes
E )
47 seconds after pre-purge
Boiler furnaces are purged:
A )
so that the programmer has time to verify permissiveness of interlocks
B )
in order to ensure combustion gases are fully removed prior to ignition
C )
while the operator is given the opportunity to check fuel and water
systems
D ) so that combustibles are
fully removed prior to ignition
E )
to cool any glowing refractory
On a gas fired automatic boiler a normal
programmed start-up takes approximately:
A ) 105 seconds
B )
55 seconds
C )
27 - 40 seconds
D )
120 seconds
E )
70 seconds
If a shutdown occurs during normal firing
of a boiler and the steam pressure is below the normal cut-out value, the problem
could be:
A )
the sensing line to the combustion air proving switch has broken
B )
main flame trial failure
C ) pilot flame trial failure
D )
ignitor transformer failure
E )
high steam pressure limit switch tripped
Automatic boiler liquid fuel manual valves
should be opened:
A ) prior to pre-purging
B )
after pre-purge and just prior to pilot ignition
C )
immediately after completion of the pilot flame trial
D )
after the automatic main burner fuel valve opens
E )
with the automatic main burner fuel valve
During a programmed start-up if an
ignitor spark is visible but no flame appears the operator
should suspect:
A ) a boiler low water level
B )
the main burner manual fuel valve is closed
C )
the pilot manual fuel valve is closed
D )
the scanner lead sulphide cell is weak
E )
boiler steam pressure operating control switch is open
The second from last step in an automatic
boiler programmed shutdown sequence is:
A )
timer shutdown
B )
main flame trial
C ) post purge
D )
operating control switch contacts closing
E )
flame failure switch contacts opening
On a boiler with high-low fire control, if
the damper positioning switch is in the wrong position:
A ) the damper motor may not
operate
B )
a pre-purge will not occur
C )
a high fire main flame ignition could occur
D )
nothing will happen when the manual start switch is closed
E )
the pre-purge period will last indefinitely unless the problem is
corrected
CH.90
On a boiler with high-low fire control, if
the damper positioning switch is in the wrong position:
A ) the damper motor may not
operate
B )
a pre-purge will not occur
C )
a high fire main flame ignition could occur
D )
nothing will happen when the manual start switch is closed
E )
the pre-purge period will last indefinitely unless the problem is
corrected
Automatic boiler liquid fuel manual valves
should be opened:
A ) prior to pre-purging
B )
after pre-purge and just prior to pilot ignition
C )
immediately after completion of the pilot flame trial
D )
after the automatic main burner fuel valve opens
E )
with the automatic main burner fuel valve
The function of a programming control is:
A )
to supervise feedwater supply to the boiler
B )
to regulate the fuel supply to the burner
C ) to regulate combustion
controls during start-up
D )
control the boiler blowdown rate
E )
to regulate fuel, air, and water supply to the boiler
Before lighting off a boiler you should
always purge the furnace in order to:
A )
prove that the furnace and stack are clear
B )
blow out any soot which may have collected in the tubes
C )
cool the furnace so that premature combustion can occur
D )
dry out the brickwork and check for leaks
E ) remove any combustible
gases which may have collected
Automatic boiler programming controls:
A )
must incorporate a modulating control system
B )
do not require interlocking devices
C ) require an ON-OFF or
two-position control switch
D )
cannot make use of high-low fire control
E )
are not interconnected with the water level control system
During the start-up of a boiler equipped
with an automatic control system and flame scanning device, the main fuel
supply valve:
A ) must be opened before
ignition can take place
B )
can be opened before the flame scanner sees a flame
C )
can be opened any time during start up sequence
D )
should be open as soon as pilot valve opens
E )
must be closed before ignition
The second from last step in an automatic
boiler programmed shutdown sequence is:
A )
timer shutdown
B )
main flame trial
C ) post purge
D )
operating control switch contacts closing
E )
flame failure switch contacts opening
The operating pressure control will control
the:
A ) steam pressure in the
boiler
B )
gas pressure to the burner
C )
water pressure to the boiler
D )
boiler furnace pressure
E )
steam pressure in the steam header
With automatic fuel fired boiler programmed
control the normal firing period begins approximately:
A )
44 seconds after FD fan starts
B )
75 seconds after FD fan starts
C ) 60 seconds after FD fan
starts
D )
10 seconds after pilot extinguishes
E )
47 seconds after pre-purge
When an automatic unattended boiler starts
up, the program timer will first:
A )
energise the ignition transformer and pilot gas solenoid valve
B )
start the post purge period
C ) start the force draft fan
D )
energise the main gas valve
E )
energise the main feed water valve
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