4B Older Practice questions Controls Flashcards
An ON-OFF steam boiler:
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. Operates most efficiently at continuous firing
A modulating control steam heating boiler:
a. Is always fully automatic
b. Will have a wide operating pressure range
c. Has very efficient operation
d. Will have a constant combustion air, flow rate
e. Cannot operate in a multi-boiler system
c. Has very efficient operation
The type of combustion fuel control frequently used on a small package boiler, is a/an:
a. Scanner
b. Modulating control
c. High fuel level cut-off
d. Constant pressure control
e. On and off control
e. On and off control
A high limit control switch:
a. Is necessary on all boilers.
b. Must be used when a boiler is not under continuous supervision.
c. Is a normally open switch.
d. Usually does not require manual resetting.
e. Activates after the safety valve opens.
b. Must be used when a boiler is not under continuous supervision.
Quickly closing the main burner manual cock valve during boiler operation should check the:
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. High gas pressure fuel cut-off
A leveling 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.
e. An ON-OFF operating control switch.
A manual “high-low” switch should be switched to “high” or “auto”:
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
d. When the boiler has been properly warmed up
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. Works in conjunction with a modutrol motor
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. Will not result in simultaneous adjustment of air and fuel
e. Eliminates the need for a high limit control
a. Varies electrical current to a modutrol motor
On a multi-burner boiler the high fire nozzle will:
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.
b. Operate continuously when steam demand exceeds boiler capacity
Prior to a boiler safety valve popping during routine boiler operation:
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
c. The high limit switch should open
A test lead or “jumper wire” is required when testing:
a. High steam pressure or water temperature limiting 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
a. High steam pressure or water temperature limiting controls
A hot water boiler operating control can be a pressure switch:
a. Which is normally open
b. Which is sensitive to the expansion and contraction of boiler water
c. Utilizing a closed liquid filled system
d. Sensitive to steam pressure
e. Sensitive to boiler steam pressure
c. Utilizing a closed liquid filled system
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. Capable of sensing temperature and converting it to a pressure signal
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
b. Is like a thermal element without a capillary tube
Modulating combustion controls
a. Regulate the steam and feedwater supply
b. Regulate the fuel and air supplies
c. Control the oil atomizer
d. Control the back draft damper
e. Control the draft and feedwater temperature
b. Regulate the fuel and air supplies
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 atomizing steam flow
d. Fuel flow and air, flow
What is the purpose of the high limit temperature control on a hot water boiler?
a. To take over operating the boiler if the water level control fails.
b. To allow you to take off the operating control for maintenance without shutting down the boiler.
c. To shut down the burner if the water temperature rises too high.
d. To prevent the pressure in the boiler rising above 210 kPa gage.
e. To limit high pressure and temperature from developing.
c. To shut down the burner if the water temperature rises too high.
The main boiler control device used with an on/off combustion fuel control is a _____ sensing element.
a. Pressure
b. Level
c. Temperature
d. Electronic
e. Pneumatic
a. Pressure
A device found on the pressure side of a boilers operating control switch is a:
a. Modutrol motor
b. Siphon
c. Combustion air proving switch
d. Test connection for an inspector
e. Feedwater pressure gage.
b. Siphon
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
e. Should be checked when air flow is maximum
An operating control switch for an ON-OFF boiler:
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
a. Uses a differential spring to reduce cycling
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. Acts as an interlock to ensure minimum damper setting
d. Utilizes a thermal element for its operation
e. Is a normally closed switch.
c. Acts as an interlock to ensure minimum damper setting
A high gas pressure fuel cut-off switch:
a. Closes when gas pressure is too high
b. Is never a manual reset device
c. Must be located upstream of an automatic fuel valve
d. Is a normally open switch
e. Opens when gas pressure is too high
e. Opens when gas pressure is too high
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. As non-interlocking devices and take no part in a startup
e. On gas fired boilers only.
c. On boilers utilizing a forced draft fan
A flame failure device:
a. Must be installed on every high pressure boiler
b. Will shut off the steam leaving the boiler
c. Will control the pressure of the boiler
d. Will shut off the fuel to the burner
e. Will shut down the flame in the boiler
d. Will shut off the fuel to the burner
Thermocouples are connected in series to:
a. Monitor more than one flame source
b. Increase the sensitivity of the detection system
c. Generate a higher voltage
d. Provide a spare thermocouple in case of failure of one
e. Generate a lower voltage
c. Generate a higher voltage
During the start-up, a boiler equipped with an automatic control system and a 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 opened as soon as the pilot valve opens
e. Must be closed before ignition.
e. Must be closed before ignition
Flame rods:
a. Should be cleaned of deposits regularly.
b. Require frequent filing of electrical contacts to prevent corrosion build-up and failure of the device.
c. Should shut off the fuel within four seconds of flame failure.
d. Are very reliable and maintenance free.
e. Should not be exposed to temperatures above 100°C.
c. Should shut off the fuel within four seconds of flame failure
All flame safeguard devices:
a. Close the main fuel valve in case of pilot flame failure or main burner failure.
b. Require a photoelectric cell.
c. Are limited to temperatures comfortable to the hand.
d. Monitor the pilot flame and main burner simultaneously.
e. Activate an alarm system if flame failure is detected
a. Close the main fuel valve in case of pilot flame failure or main burner failure.
The maximum allowable temperature for the water in a hot water heating boiler is:
a. 100°C b. 150°C c. 121°C d. 170°C e. 250°C.
c. 121°C
A flame scanner:
- Requires a photoelectric cell
- Responds to temperature changes
- Requires a clear line of sight to the flame
- Produces a steady voltage signal
a. 1, 2, 3, 4
b. 2, 3
c. 1, 2, 4
d. 1, 3
e. 2, 3, 4.
d. 1, 3
The “Purple Peeper” scans the boiler furnace for radiation in the _____ range.
a. Visible
b. Ultrasonic
c. Infrared
d. Invisible
e. Ultraviolet
e. Ultraviolet.
The requirement for each automatically fired hot water heating or hot water supply boiler to be protected from over temperature by two temperature-operated controls is stated in:
a. ASME Section I
b. ASME Section IV
c. CSA B-51
d. Alberta Pressure Equipment Safety Regulation
e. Alberta Power Engineers Regulation.
b. ASME Section IV
The current code that covers hot water heating or hot water supply boilers that operate at temperatures not exceeding 120°C is:
a. ASME Section I
b. ASME Section IV
c. CSA B-51
d. Alberta Pressure Equipment Safety Regulation
e. Alberta Power Engineers Regulation
b. ASME Section IV
Boiler fuel should be shut off immediately if it fails to ignite to:
a. Save fuel
b. Prevent furnace explosions
c. Prevent spills
d. Save power
e. Prevent boiler corrosion
b. Prevent furnace explosions
Flame safeguard devices:
a. Should be tested following the manufacturers instructions
b. Should be kept as far away from the fire as possible
c. Should not be cleaned except by a qualified serviceman
d. Should be kept cool enough to be touched by hand
e. Are all unaffected by heat
a. Should be tested following the manufacturers instructions
Which of the following is a flame, sensing device?
a. Thermopile
b. Heat sensing control
c. Stack relay
d. Cut-off valve
e. Scanner.
e. Scanner
A thermocouple:
a. Consists of two similar wires
b. Produces an electric signal
c. Senses infrared light from the flame
d. Senses changes in fuel line pressure
e. Senses changes in air pressure.
b. Produces an electric signal
The function of a flame failure device is to:
a. Shut off the fuel supply when the pressure gets too high
b. Shut off the fuel when the burner flame goes out
c. Shut off the fuel when the fuel temperature is high
d. Shut off the feedwater supply to the boiler
e. De-energize the fan and feedwater systems.
b. Shut off the fuel when the burner flame goes out
High limit temperature controls:
a. Increase air, flow to the boiler if temperature limits are exceeded
b. Open a 3-way mixing valve to add cold water to the hot water to reduce the water temperature
c. Shut off the fuel if the water temperature is too high
d. Are required under Section II of the ASME Codes
e. Are required on steam boilers.
c. Shut off the fuel if the water temperature is too high
A flame rod:
a. Forms an electric circuit with the rod, flame and relay
b. Is used for gas and oil fired burners
c. Forms an electric circuit with the rod, flame and burner
d. Senses the temperature of the flame
e. Is used to light the main burner
c. Forms an electric circuit with the rod, flame and burner
An example of a final control device for a heating system is a:
a. Slide-gate
b. Pump
c. Fan
d. Set of louvers
e. All of the above
e. All of the above
Pneumatic controllers are divided into two basic classes:
a. Direct and indirect
b. Off/on and proportional
c. Positive and negative action
d. Bleed and non-bleed
e. Reset and gain
d. Bleed and non-bleed
In a non-bleed type controller the device that senses a change in room temperature is called a:
a. Sensing valve
b. Bellows
c. Set point gage
d. Temperature switch
e. Feedback switch.
b. Bellows
An example of an auxiliary device for a pneumatic control system would be a:
a. Reducing valve
b. Three way air valve
c. Damper
d. Pump
e. Bellows.
b. Three way air valve
In a self-contained control system the energy for operation is provided by:
a. Electricity
b. Air pressure
c. The reaction of the sensing device
d. A bellows
e. A bleed type nozzle
c. The reaction of the sensing device
Parallel blade dampers are usually used for:
a. Changing the direction of the air flow
b. Varying the amount of air flow
c. Turning the air flow on or off
d. Proportional operation
e. Mixed air control (outside and inside air).
c. Turning the air flow on or off
The device used to maintain a constant pressure throughout a pneumatic control system is called a:
a. Reducing valve
b. Control regulator
c. Pneumatic valve
d. Balancing valve
e. Proportional band controller
a. Reducing valve
A pneumatic control system:
a. Uses a sensing device to change pressures in the control line
b. Requires an intermittent air supply
c. Always uses pressure actuated final controlled devices
d. Is not used to control air flow for ventilation
e. Is seldom used to control humidity.
a. Uses a sensing device to change pressures in the control line
The most common type of damper operator is a:
a. Slide
b. Ramp
c. Bellows
d. Piston
e. Pilot positioner
d. Piston
A pneumatic relay can also be called a:
a. Selector switch
b. Air reservoir
c. Bleed type controller
d. Cumulator
e. Pneumatic-electric switch
d. Cumulator
The effective range of control pressure used in 100 kPa circuits is usually considered to be from:
a. 20 to 90 kPa
b. 0 to 100 kPa
c. 3 to 15 kPa
d. 2 to 25 kPa
e. 15 to 75 kPa.
a. 20 to 90 kPa
A pneumatic control system consists of four essential parts:
- An air compressor with storage tank, filter, and reducing valve.
- Air piping and tubing forming the air distribution system.
- Controllers such as rheostats.
- Controlled devices such as convector valves, zone valves, and damper operators.
a. 1, 2, 3
b. 2, 3, 4
c. 1, 2, 4
d. 1, 3, 4
e. 1, 2, 3, 4.
c. 1, 2, 4
Dual temperature thermostats are set at two different temperatures and the transfer from one to the other is made by, changing the supply air pressure from:
a. 3 kPa to 15 kPa
b. 5 kPa to 25 kPa
c. 20 kPa to 90 kPa
d. 0 kPa to 100 kPa
e. 100 kPa to 125 kPa
e. 100 kPa to 125 kPa.
In the pneumatic control nozzle and vane system the:
a. Vane approaches the nozzle increasing air pressure
b. Vane approaches the nozzle decreasing air pressure
c. Nozzle pressure increases moving the vane further away
d. Nozzle pressure decreases allowing the vane to move closer
e. Vane and nozzle both move to maintain equilibrium
a. Vane approaches the nozzle increasing air pressure
A non-bleed controller bleeds control air:
a. When the supply pressure is decreased
b. When the supply pressure is increased
c. Non-bleed controllers do not bleed air
d. When the control air pressure is increased
e. When the control air pressure is decreased
e. When the control air pressure is decreased
A device used to position dampers and control valves is, termed:
a. A controller
b. A relay
c. A transformer
d. An actuator
e. A temperature controller
d. An actuator
Thermostats may be classified according to there:
a. Application
b. Type of temperature sensing element
c. Type of control action provided
d. Temperature range
e. All of the above
e. All of the above
A room thermostat should be mounted on an inside wall about _____ above the floor.
a. 0.5 m b. 0.75 m c. 1.0 m d. 1.25 m e. 1.5 m.
e. 1.5 m.
In a basic electric control system an example of a controlled device is:
a. A fuel valve
b. A louver
c. A diverter valve
d. An electric switch
e. All of the above
e. All of the above.
In a basic electrical control system the device that senses a drop in air temperature is called the:
a. Final controlled device
b. Pneumatic temperature sensor
c. Humidistat
d. Thermostat
e. Regulator.
d. Thermostat
- Pressure controllers can be divided into two classes:
a. High and low temperature
b. High and low pressure
c. High and low flow
d. Inside and outside mounting
e. Horizontal or vertical mounting.
b. High and low pressure
- An example of a controlled device would be a:
a. Damper motor operating air louvers
b. Hot water boiler
c. Radiator
d. Steam boiler
e. Thermostat.
a. Damper motor operating air louvers
Control motors are divided into two classifications:
a. Large and small
b. AC and DC
c. Valve operators and damper operators
d. High voltage and low voltage
e. Pump and fan controllers
c. Valve operators and damper operators
- On-off thermostats are equipped with:
a. An open contact switch
b. A high temperature switch
c. A low temperature switch
d. A high voltage switch
e. A low voltage switch
a. An open contact switch
The bimetal sensing element consists of a strip made up of two thin layers of metal with:
a. Similar rates of thermal expansion
b. Widely different rates of thermal expansion
c. Slightly different rates of thermal expansion
d. Widely different rates of thermal conductivity
e. Slightly different rates of thermal conductivity
b. Widely different rates of thermal expansion
In electric switch configuration the term “contact arrangement refers to:
a. Normally open or normally closed position
b. Switches in series or parallel
c. Double or single pole switches
d. Switches mounted vertically or horizontally
e. Relay contacts.
a. Normally open or normally closed position
_____ is the term that refers to the normal electric supply voltage.
a. Extra low voltage
b. Low voltage
c. High voltage
d. Line voltage
e. Very high voltage
d. Line voltage
A transformer is a device that is used to change:
a. AC amperage from one value to another
b. AC voltage from one value to another
c. DC amperage from one value to another
d. DC voltage from one value to another
e. Both AC and DC voltages.
b. AC voltage from one value to another
Using electricity for control purposes has the following advantages:
- It is readily available
- The wiring is usually simple and easy to install
- Signals from sensing elements can produce one output
- Controller/actuators do not require an air supply
a. 1, 2, 3
b. 2, 3, 4
c. 1, 2, 4
d. 1, 3, 4
e. 1, 2, 3, 4.
c. 1, 2, 4
A bimetal thermostat’s operating range is between:
a. 5 and 40°C b. 0 and 50°C c. 0 and 40°C d. 10 and 32°C e. 50 and 90°C.
d. 10 and 32°C
- An electronic control system is comprised of a:
a. Meter, sensor, and valve
b. Sensor, controller, and final control element
c. Sensor, transmitter, and thermostat
d. Controller, thermostat, and sensor
e. Thermostat, electronic controls, and furnace
b. Sensor, controller, and final control element
An advantage of an electronic control system is that:
a. The controllers can accept a wide variety of inputs
b. They are inexpensive to operate
c. They are inexpensive to install
d. The controllers can be used outdoors
e. It is very compact
a. The controllers can accept a wide variety of inputs
An example of a final control element is a:
a. Thermostat
b. Fire eye
c. Relay
d. Damper
e. Thermocouple.
d. Damper
Transmitters or transducers can measure:
a. Temperature
b. Air flow
c. Air flow velocity
d. Water flow
e. All of the above
e. All of the above
Authority or Compensation Authority is the:
a. A process of automatically adjusting the control point of a controller.
b. Point in which the compensation effect is reversed in action.
c. System element that senses a variable other than the controlled variable.
d. A setting that indicates the relative effect a compensating sensor has on the main setpoint.
e. Entity that awards compensation after a workplace injury.
d. A setting that indicates the relative effect a compensating sensor has on the main setpoint
- Deviation is the difference between the setpoint of a controller and the value of the controlled variable it is also called:
a. Error
b. Proportional band
c. Offset
d. Integral
e. Gain.
c. Offset
The electrical resistance of a thermistor will:
a. Decrease when cooled
b. Decrease when heated
c. Increase when heated
d. Remain constant with temperature changes
e. None of the above.
b. Decrease when heated
A pressure sensor converts pressure changes into:
a. An electrical signal
b. A change in electrical resistance
c. Variables such as voltage, current, or resistance
d. Air pressure
e. A temperature change.
c. Variables such as voltage, current, or resistance
Electronic controllers can be divided into two types:
a. On or off
b. Modulating and direct acting
c. Indirect and direct acting
d. On or off and modulating
e. Actuators and relays
d. On or off and modulating
A transducer is a device that is used to:
a. Generate a set point
b. Produce an off or on signal
c. Convert an electronic signal to a pneumatic signal
d. Amplify an electronic signal
e. Filter an electronic signal
c. Convert an electronic signal to a pneumatic signal
Resistance temperature devices can provide a relatively linear resistance variation from:
a. -60 to 80°C b. -40 to 120°C c. -40 to 250°C d. 0 to 100°C e. 40 to 100°C
b. -40 to 120°C
An electronic controller is:
a. Not part of the electronic control system
b. Used to position an actuator
c. Used to generate a set point
d. A type of sensor
e. Used only in pneumatic systems
b. Used to position an actuator
A direct acting controller:
a. Increases its output signal on an increased input signal.
b. Increases its output signal on a decreased input signal.
c. Increases its output signal on an increased output signal.
d. Increases its input signal on an increased output signal.
e. Decreases its output signal on an increased input signal
a. Increases its output signal on an increased input signal
Proportional band or throttling range is the:
a. Control method in which the final control element moves proportionally to the deviation of the controlled variable from the setpoint.
b. Control algorithm that combines the proportional and integral response control algorithms.
c. Compensation action where a decrease in the compensation variable has the same effect as an increase in the controlled variable.
d. Control point range through which the controlled variable must pass to drive the final control element through its full range.
e. Sustained deviation between the control point and the setpoint of a proportional control system under stable operating conditions.
d. Control point range through which the controlled variable must pass to drive the final control element through its full range.
A reverse acting controller:
a. Increases its output signal on a decreased output signal.
b. Decreases its output signal on an increased input signal.
c. Increases its output signal on an increased output signal.
d. Decreases its input signal on an increased output signal.
e. Decreases its output signal on a decreased input signal.
b. Decreases its output signal on an increased input signal.
