3e151 B Set Vol 2

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UREs for B set of 3E151 cdcs Vol 2.


Questions and Answers
  • 1. 

    The inside part of the a heat exchanger in a forced-warm air furnace is known as the

    • A.

      Burner cone

    • B.

      Draft chamber

    • C.

      Casing chamber

    • D.

      Combustion chamber

    Correct Answer
    D. Combustion chamber
    Explanation
    The inside part of a heat exchanger in a forced-warm air furnace is known as the combustion chamber. This is where the fuel and air mix and ignite to produce heat. The combustion chamber is designed to efficiently burn the fuel and transfer the heat to the surrounding air. It is an essential component of the furnace as it is responsible for generating the heat that is then distributed throughout the building. The burner cone, draft chamber, and casing chamber are not the correct terms for the inside part of a heat exchanger in a forced-warm air furnace.

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  • 2. 

    Three common types of bearing used on warm-air furnace assemblies

    • A.

      Anti-friction, sleeve, and bronze

    • B.

      Sleeve, thrust, and anti-friction

    • C.

      Plain, thrust, and anti-friction

    • D.

      Thrust, plain, and bronze

    Correct Answer
    B. Sleeve, thrust, and anti-friction
    Explanation
    The correct answer is sleeve, thrust, and anti-friction. These are the three common types of bearings used on warm-air furnace assemblies. A sleeve bearing is a type of plain bearing that consists of a cylindrical sleeve that supports the rotating shaft. A thrust bearing is designed to handle axial loads and is used to prevent axial movement of the shaft. Anti-friction bearings, also known as rolling element bearings, reduce friction by using rolling elements such as balls or rollers between the stationary and rotating parts.

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  • 3. 

    What type of warm-air furnace is known as a high-boy furnace?

    • A.

      Horizontal

    • B.

      Downflow

    • C.

      Gravity

    • D.

      Upflow

    Correct Answer
    D. Upflow
    Explanation
    An upflow warm-air furnace is known as a high-boy furnace because it is designed to be installed in an upright position, with the air intake at the bottom and the warm air discharge at the top. This configuration allows for efficient heating as the warm air rises and circulates throughout the room. The term "high-boy" refers to the furnace's taller and more slender profile compared to other types of warm-air furnaces.

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  • 4. 

    Gas burners primary controls operate in response to signals received from

    • A.

      Relays

    • B.

      Switches

    • C.

      Thermostats

    • D.

      A heating element

    Correct Answer
    C. Thermostats
    Explanation
    Gas burners primary controls operate in response to signals received from thermostats. Thermostats are devices that sense the temperature in the surrounding environment and send signals to the primary controls of the gas burner to adjust the flame accordingly. This allows the gas burner to maintain a desired temperature by turning on or off the gas supply based on the thermostat's signals. Switches and relays may be used in the overall control system, but the primary control and regulation of the gas burner is achieved through the use of thermostats.

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  • 5. 

    When the tempetature in a gas-fired furnance becomes excessive, what unit stops the burner?

    • A.

      Delayed-action control

    • B.

      Starting control

    • C.

      Ignition control

    • D.

      Limit control

    Correct Answer
    D. Limit control
    Explanation
    The limit control unit is responsible for stopping the burner in a gas-fired furnace when the temperature becomes excessive. This unit acts as a safety mechanism to prevent overheating and potential damage to the furnace or surrounding areas. It monitors the temperature and when it reaches a predetermined limit, it sends a signal to shut off the burner, ensuring that the temperature remains within a safe range.

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  • 6. 

    The delayed-action control is a primary control that is usually used with 

    • A.

      A stoker

    • B.

      An oil burner

    • C.

      A gas burner

    • D.

      A coal hand-fired furnace

    Correct Answer
    B. An oil burner
    Explanation
    The delayed-action control is a primary control that is usually used with an oil burner. This control is designed to delay the ignition of the oil until the proper conditions are met, such as the presence of sufficient airflow or the absence of any safety hazards. By delaying the ignition, the control helps to ensure safe and efficient operation of the oil burner. It allows for proper fuel atomization and combustion, resulting in optimal performance and reduced emissions. Therefore, an oil burner is the most suitable option for the delayed-action control.

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  • 7. 

    The most important inspection you perform on a gas-fired furnace is one for 

    • A.

      Power

    • B.

      Unit size

    • C.

      A gas leak

    • D.

      Unit location

    Correct Answer
    C. A gas leak
    Explanation
    The most important inspection to perform on a gas-fired furnace is for a gas leak. This is crucial because a gas leak can be extremely dangerous, leading to potential explosions or carbon monoxide poisoning. Detecting and fixing a gas leak ensures the safety of the occupants and prevents any potential hazards.

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  • 8. 

    What is the most serious defect to look for when you inspet a heat exchanger?

    • A.

      Warped metal

    • B.

      Soot deposits

    • C.

      Blockages

    • D.

      Cracks

    Correct Answer
    D. Cracks
    Explanation
    When inspecting a heat exchanger, the most serious defect to look for is cracks. Cracks in a heat exchanger can lead to leakage of fluids or gases, which can result in reduced efficiency or even complete failure of the system. Cracks can also pose safety hazards, such as the risk of fire or explosion. Therefore, identifying and addressing cracks in a heat exchanger is crucial to ensure its proper functioning and prevent any potential damage or accidents.

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  • 9. 

    When you perform a test to ensure that the safety limit control is operating properly, which circuit do you disconnect?

    • A.

      Blower

    • B.

      Burner

    • C.

      Pilot

    • D.

      Main

    Correct Answer
    A. Blower
    Explanation
    To perform a test on the safety limit control, the blower circuit needs to be disconnected. This is because the blower is responsible for circulating air through the system, and disconnecting it will allow for a controlled test of the safety limit control without the blower's interference. By disconnecting the blower circuit, you can ensure that the safety limit control is functioning correctly and independently from the blower.

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  • 10. 

    What type of gas space heaters can be gravity or mechanical air-circulation type and vented or unvented type?

    • A.

      Ceiling

    • B.

      Floor

    • C.

      Room

    • D.

      Wall

    Correct Answer
    C. Room
    Explanation
    Gas space heaters can be of different types based on the way they circulate air and whether they are vented or unvented. The options provided in the question, such as ceiling, floor, and wall, refer to the physical location of the heaters. However, the correct answer, "room," refers to the type of gas space heaters that can be both gravity or mechanical air-circulation type and vented or unvented. In other words, gas space heaters designed for rooms can have different air-circulation mechanisms and venting options.

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  • 11. 

    Which space heater must be used inly in a well-ventilated rooms?

    • A.

      Wall

    • B.

      Room

    • C.

      Vented

    • D.

      Unvented

    Correct Answer
    D. Unvented
    Explanation
    An unvented space heater must be used only in well-ventilated rooms because it does not have an exhaust or vent to remove the combustion byproducts, such as carbon monoxide, outside. Without proper ventilation, these byproducts can accumulate in the room and pose a serious health risk to the occupants. Therefore, it is important to use an unvented space heater only in a well-ventilated area to ensure the safety and well-being of everyone in the room.

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  • 12. 

    What is the maximum Btu input for an unvented space heater?

    • A.

      50,000 btu/h

    • B.

      40,000 btu/h

    • C.

      30,000 btu/h

    • D.

      20,000 btu/h

    Correct Answer
    B. 40,000 btu/h
    Explanation
    An unvented space heater refers to a heating device that does not require a chimney or vent to release combustion byproducts. The maximum Btu input for an unvented space heater refers to the highest amount of heat energy that the heater can produce in an hour. In this case, the correct answer is 40,000 btu/h, which means that this particular unvented space heater can generate a maximum of 40,000 British thermal units of heat energy per hour.

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  • 13. 

    Which type of space heater control valve has an infinite number of fuel firing rates between high fire and low fire?

    • A.

      Step-modulating

    • B.

      Single-stage

    • C.

      Two-stage

    • D.

      Manual

    Correct Answer
    A. Step-modulating
    Explanation
    A step-modulating space heater control valve has an infinite number of fuel firing rates between high fire and low fire. This means that it can adjust the fuel flow in small increments, allowing for precise control of the heating output. Unlike single-stage or two-stage valves, which have fixed firing rates, a step-modulating valve offers more flexibility and efficiency in regulating the heat output of the space heater. A manual valve, on the other hand, requires manual adjustment and does not provide the same level of control as a step-modulating valve.

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  • 14. 

    Whose instructions must you follow when you inspect gas-fired heaters?

    • A.

      Air force bulletins

    • B.

      Air force procedures

    • C.

      Manufacturers' instructions

    • D.

      Local procedures and air force bulletins

    Correct Answer
    C. Manufacturers' instructions
    Explanation
    When inspecting gas-fired heaters, it is important to follow the manufacturers' instructions. These instructions are provided by the manufacturers who have the expertise and knowledge about their specific heaters. They outline the proper procedures and guidelines for inspecting and maintaining the heaters to ensure their safe and efficient operation. Following these instructions is crucial to ensure the safety of the inspector and to avoid any potential damage or malfunction of the heaters.

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  • 15. 

    What method of heat transfer is used when floors or other objects reradiate to the air?

    • A.

      Conduction

    • B.

      Convection

    • C.

      Radiation

    • D.

      Absorption

    Correct Answer
    B. Convection
    Explanation
    When floors or other objects reradiate heat to the air, the method of heat transfer being used is convection. Convection is the process by which heat is transferred through the movement of fluids, such as air or water. In this case, the heat from the floors or objects is transferred to the surrounding air through convection, as the air near the objects gets heated and rises, creating a convection current that spreads the heat throughout the room.

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  • 16. 

    Infrared heaters are not used in an area that contains ignitable dust, gases, or vapors in hazardous concentrations because of

    • A.

      Their very low surface temperature

    • B.

      Their high surface temperature

    • C.

      The porosity of their ceramic elements

    • D.

      The possibility of corrosion damage to the elements

    Correct Answer
    B. Their high surface temperature
    Explanation
    Infrared heaters are not used in areas with ignitable dust, gases, or vapors in hazardous concentrations because of their high surface temperature. This is because the high surface temperature of the heater can potentially ignite or cause explosions when it comes into contact with these hazardous substances. Therefore, it is safer to use other heating methods in such environments to prevent any potential accidents or hazards.

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  • 17. 

    The fan control has two settings; the fan OFF temperature is generally set at

    • A.

      20 to 25*F above the desired room temperature

    • B.

      15 to 20*F above the desired room temperature

    • C.

      10 to 15*F above the desired room temperature

    • D.

      5 to 10*F above the desired room temperature

    Correct Answer
    D. 5 to 10*F above the desired room temperature
    Explanation
    The correct answer is 5 to 10*F above the desired room temperature. This is because the fan control is designed to turn on the fan when the room temperature exceeds the desired temperature by a certain range. Setting the fan OFF temperature at 5 to 10*F above the desired room temperature ensures that the fan will turn off once the room temperature reaches the desired level, preventing excessive cooling and energy waste.

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  • 18. 

    While troubleshooting a warm-air heating system, you notice the flame burning in a long, yellow-tipped manner?  What would cause this to happen?

    • A.

      A strong updraft

    • B.

      A very weak cross draft

    • C.

      Low voltage in the control circuit

    • D.

      Insufficient primary combustion

    Correct Answer
    D. Insufficient primary combustion
    Explanation
    The flame burning in a long, yellow-tipped manner is indicative of insufficient primary combustion. This means that the fuel-air mixture is not being properly ignited, resulting in an incomplete combustion process. This could be caused by factors such as a clogged or dirty burner, inadequate air supply, or improper fuel delivery. Insufficient primary combustion can lead to reduced heating efficiency, increased fuel consumption, and potentially the release of harmful gases.

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  • 19. 

    When troubleshooting a gas-fired warm-air furnace, the unit is functioning eletrically but does not operate. What could be the cause of the type malfunction?

    • A.

      An open gas valve

    • B.

      A closed gas valve

    • C.

      An open alarm circuit

    • D.

      A closed thermostat circuit

    Correct Answer
    B. A closed gas valve
    Explanation
    A closed gas valve could be the cause of the malfunction in the gas-fired warm-air furnace. Even though the unit is functioning electrically, if the gas valve is closed, no gas will be able to flow into the furnace, preventing it from operating.

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  • 20. 

    What surrounds the tubes of water-tube boiler?

    • A.

      Hot gases

    • B.

      Hot air

    • C.

      Water

    • D.

      Steam

    Correct Answer
    A. Hot gases
    Explanation
    The tubes of a water-tube boiler are surrounded by hot gases. In a water-tube boiler, the water flows through the tubes while the hot gases produced by burning fuel surround the tubes. This design allows for efficient heat transfer from the hot gases to the water, resulting in the generation of steam. Hot air, water, and steam are not the correct answers as they do not directly surround the tubes in a water-tube boiler.

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  • 21. 

    An increase in pressure and the surface of water will

    • A.

      Increase the boiling point

    • B.

      Decrease the boiling point

    • C.

      Increase the molecular count

    • D.

      Decrease the molecular count

    Correct Answer
    A. Increase the boiling point
    Explanation
    When pressure is increased, the boiling point of water also increases. This is because an increase in pressure compresses the water molecules, making it harder for them to escape into the gas phase. As a result, more heat is required to break the intermolecular forces and convert water into vapor. Therefore, an increase in pressure raises the boiling point of water.

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  • 22. 

    The formula for determining the temperature of water at a given steam pressure is

    • A.

      Square root of the psi + 14 x 198

    • B.

      Square root of the psi x 14 + 198

    • C.

      198 X 14 + square root of the psi

    • D.

      198 + 14 x the square root of the psi

    Correct Answer
    B. Square root of the psi x 14 + 198
    Explanation
    The correct formula for determining the temperature of water at a given steam pressure is the square root of the psi multiplied by 14, and then adding 198.

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  • 23. 

    The internal feedline is installed in the water space near, but not touching, the

    • A.

      Downcomer tubes

    • B.

      Side of the drum

    • C.

      Bottom of the drum

    • D.

      Surface blowdown line

    Correct Answer
    C. Bottom of the drum
    Explanation
    The internal feedline is installed at the bottom of the drum. This location allows for efficient transfer of water from the drum to the downcomer tubes, which are located near the side of the drum. Placing the feedline at the bottom ensures that it is submerged in the water, allowing for a continuous flow of water to the downcomer tubes. Additionally, this location helps prevent any interference with the surface blowdown line, which is typically located at the top of the drum.

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  • 24. 

    Flat surfaces of a boiler are held in place by braces, which are called

    • A.

      Baffles

    • B.

      Tubes

    • C.

      Stays

    • D.

      Drums

    Correct Answer
    C. Stays
    Explanation
    The correct answer is "stays." In a boiler, the flat surfaces are held in place by braces called stays. Stays are structural components that provide support and prevent movement or deformation of the flat surfaces. They help maintain the integrity and stability of the boiler structure, ensuring that the flat surfaces remain securely in place during operation.

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  • 25. 

    Water hammer in a piping sysytem is prevented by using

    • A.

      Open traps

    • B.

      Flash tanks

    • C.

      Saturated pressure

    • D.

      Pressure release valves

    Correct Answer
    B. Flash tanks
    Explanation
    Water hammer in a piping system is a phenomenon that occurs when there is a sudden change in the flow velocity of water, resulting in pressure surges and vibrations. Flash tanks are used to prevent water hammer by providing a space for the sudden increase in pressure to be absorbed. When there is a surge in pressure, the flash tank allows the excess water and steam to be released, preventing the pressure from damaging the piping system. Open traps, saturated pressure, and pressure release valves do not specifically address the issue of water hammer prevention.

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  • 26. 

    In an 8-hour shift, how many times should you blow down a steam boiler?

    • A.

      Four

    • B.

      Three

    • C.

      Two

    • D.

      One

    Correct Answer
    D. One
    Explanation
    In an 8-hour shift, you should blow down a steam boiler only once. Blowing down a steam boiler refers to the process of removing sediment and impurities from the boiler water. This is done to maintain the efficiency and safety of the boiler. Blowing down the boiler once during an 8-hour shift ensures that any buildup of sediment or impurities is removed, preventing potential issues with the boiler's performance.

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  • 27. 

    What is the first step involved in the blowdown procedure?

    • A.

      Open the blowdown valve closest to the boiler first

    • B.

      Open the blowdown valve farthest to the boiler first

    • C.

      Close the blowdown valve closest to the boiler first

    • D.

      Close the blowdown valve farthest to the boiler first

    Correct Answer
    A. Open the blowdown valve closest to the boiler first
    Explanation
    The first step involved in the blowdown procedure is to open the blowdown valve closest to the boiler first. This allows for the release of any impurities or sediments that may have accumulated in the boiler. By opening the valve closest to the boiler, it ensures that the initial discharge is from the area where most of the impurities are likely to be present. This helps in maintaining the efficiency and safety of the boiler system.

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  • 28. 

    The purpose of a continuous blowdown system is to maintain the concentration of the boiler water at the proper limits and remove

    • A.

      Chemicals from the boiler

    • B.

      Foreign soilds from the boiler water

    • C.

      Sludge from the bottom of the boiler

    • D.

      Calcium from the bottom of the boiler

    Correct Answer
    B. Foreign soilds from the boiler water
    Explanation
    A continuous blowdown system is designed to maintain the concentration of the boiler water within the appropriate limits. One of its main functions is to remove foreign solids from the boiler water. These foreign solids can include impurities, such as dirt, rust, and other contaminants that may accumulate in the boiler system. By removing these foreign solids, the blowdown system helps to prevent potential blockages, corrosion, and other issues that can arise from the presence of these impurities in the boiler water.

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  • 29. 

    Which of following is noramally found on a continous blowdown system?

    • A.

      Collecting takeoff line

    • B.

      Safety relief valves

    • C.

      Gauge glasses

    • D.

      Limit switches

    Correct Answer
    A. Collecting takeoff line
    Explanation
    A continuous blowdown system is used to remove impurities and maintain the desired level of dissolved solids in a boiler. The collecting takeoff line is an essential component of this system. It collects the blowdown water from the boiler and transports it to a suitable location for further treatment or disposal. Safety relief valves are used to release excess pressure in the boiler, gauge glasses are used to monitor the water level, and limit switches are used to control the operation of various components in the system. However, these components are not specifically related to a continuous blowdown system.

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  • 30. 

    Water columns are contructed of 

    • A.

      Aluminum

    • B.

      Pig iron

    • C.

      Cast iron

    • D.

      Stainless steel

    Correct Answer
    C. Cast iron
    Explanation
    Cast iron is a suitable material for constructing water columns because it is known for its durability and strength. It can withstand high pressure and is resistant to corrosion, making it ideal for use in water systems. Cast iron also has good heat retention properties, which can be beneficial in regulating the temperature of the water. Additionally, cast iron is relatively inexpensive compared to other materials like stainless steel, making it a cost-effective choice for constructing water columns.

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  • 31. 

    Pipe used to connect the water column to the boiler must not be less than

    • A.

      1 inch

    • B.

      1 1/4 inch

    • C.

      1 1/2 inch

    • D.

      2 inches

    Correct Answer
    A. 1 inch
    Explanation
    The pipe used to connect the water column to the boiler must not be less than 1 inch in diameter. This is because a smaller pipe would restrict the flow of water and potentially cause issues with the boiler's operation. A larger pipe may not be necessary and could result in unnecessary costs and complications. Therefore, a 1-inch pipe is the appropriate size for this connection.

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  • 32. 

    Water-gauge glasses are used to indicate the 

    • A.

      Color of the boiler water

    • B.

      Boiler operating pressure

    • C.

      Water level of the boiler

    • D.

      Amount of fluctuation in the boiler

    Correct Answer
    C. Water level of the boiler
    Explanation
    Water-gauge glasses are transparent tubes that are attached to a boiler to indicate the water level inside it. The water level in a boiler needs to be monitored to ensure safe and efficient operation. By observing the water-gauge glass, operators can determine if the water level is too low or too high, which can help prevent damage to the boiler and maintain proper steam production. Therefore, the correct answer is that water-gauge glasses are used to indicate the water level of the boiler.

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  • 33. 

    How many inches above the highest point of the tubes, flues or crown sheets are horizontal fire-tube boiler gauge glasses mounted to allow water to accumulate?

    • A.

      1

    • B.

      2

    • C.

      3

    • D.

      4

    Correct Answer
    C. 3
    Explanation
    Horizontal fire-tube boiler gauge glasses are mounted 3 inches above the highest point of the tubes, flues, or crown sheets. This positioning allows water to accumulate in the gauge glasses, providing an accurate measurement of the water level in the boiler.

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  • 34. 

    What acuates the water column high- and low-water alarms?

    • A.

      Floats and weights

    • B.

      Floats and probes

    • C.

      Dual sensors and weights

    • D.

      Dual sensors and probes

    Correct Answer
    A. Floats and weights
    Explanation
    Floats and weights are used to acuate the water column high- and low-water alarms. The floats are designed to rise or fall with the water level, triggering the alarm when it reaches a certain point. The weights are used to ensure that the floats are properly balanced and can accurately indicate the water level. Together, the floats and weights provide a reliable mechanism for detecting high and low water levels in the water column.

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  • 35. 

    What type of valve is used on a steam boiler to relieve excesive pressure?

    • A.

      Gate

    • B.

      Relief

    • C.

      Safety

    • D.

      Pressure

    Correct Answer
    C. Safety
    Explanation
    A safety valve is used on a steam boiler to relieve excessive pressure. This valve is designed to automatically open and release steam when the pressure inside the boiler exceeds a certain set point. It helps prevent the boiler from exploding or causing any damage due to high pressure.

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  • 36. 

    What keeps a safety valve closed against the force developed by the steam pressure acting under the valve disc?

    • A.

      A compressed bellows

    • B.

      A compressed spring

    • C.

      A compressed nut

    • D.

      A bellows

    Correct Answer
    B. A compressed spring
    Explanation
    A compressed spring keeps a safety valve closed against the force developed by the steam pressure acting under the valve disc. When the steam pressure exceeds a certain level, the force exerted by the compressed spring is overcome, causing the safety valve to open and release the excess pressure. The compressed spring acts as a mechanical mechanism to maintain the valve in a closed position until the pressure reaches a critical point.

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  • 37. 

    A steam-stop valve must be of the outside screw-and-yoke, rising-stem typewhenever it is 

    • A.

      2 inches or less

    • B.

      2 inches or larger

    • C.

      The only valve used

    • D.

      Used with a nonreturn valve

    Correct Answer
    B. 2 inches or larger
    Explanation
    A steam-stop valve must be of the outside screw-and-yoke, rising-stem type whenever it is 2 inches or larger. This means that for steam-stop valves that are 2 inches or larger in size, they should have an outside screw-and-yoke mechanism with a rising stem. This type of valve design allows for better control and regulation of steam flow in larger systems.

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  • 38. 

    Two steam-stop valves are required when two or more boilers are connected to a common steam line to

    • A.

      Increase efficiency

    • B.

      Regulate the steam flow

    • C.

      Allow warm-up steam into a cold boiler

    • D.

      Prevent steam from entering an idle boiler

    Correct Answer
    D. Prevent steam from entering an idle boiler
    Explanation
    When two or more boilers are connected to a common steam line, having two steam-stop valves is necessary to prevent steam from entering an idle boiler. This is important because if steam were to enter an idle boiler, it could cause damage or lead to inefficiency in the system. By having two valves, one can be closed while the other remains open, ensuring that steam only flows into the active boilers and not into the idle ones.

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  • 39. 

    At least how many means of feeding water must all boilers with 500 square feet or more of water heating surface have?

    • A.

      One

    • B.

      Two

    • C.

      Three

    • D.

      Four

    Correct Answer
    B. Two
    Explanation
    Boilers with 500 square feet or more of water heating surface must have at least two means of feeding water. This is necessary to ensure a reliable and continuous water supply to the boiler for efficient operation and to prevent any potential damage or failure. Having multiple means of feeding water also provides redundancy in case one system fails or requires maintenance, allowing the boiler to continue functioning without interruption.

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  • 40. 

    What are the two types of low-water cutoffs used on steam boilers?

    • A.

      Float and switch

    • B.

      Float and probe

    • C.

      Lever and switch

    • D.

      Lever and probe

    Correct Answer
    B. Float and probe
    Explanation
    The correct answer is float and probe. Float and probe are the two types of low-water cutoffs used on steam boilers. A float type low-water cutoff operates by using a float to detect the water level in the boiler and shut off the burner if the water level drops too low. A probe type low-water cutoff uses a probe to directly sense the water level in the boiler and shut off the burner if the water level falls below a certain point. These cutoffs are important safety devices to prevent damage to the boiler and ensure proper operation.

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  • 41. 

    The boiler low-water cutoff unit protects the equipment by doing all of the except

    • A.

      Stopping operation of the burner

    • B.

      Activating the feedwater system

    • C.

      Bypassing the feedwater heater

    • D.

      Activating a low-water bell

    Correct Answer
    C. Bypassing the feedwater heater
    Explanation
    The boiler low-water cutoff unit is responsible for protecting the equipment from damage caused by low water levels. It does this by stopping the operation of the burner, activating the feedwater system, and activating a low-water bell to alert the operator. However, it does not bypass the feedwater heater. By not bypassing the feedwater heater, the unit ensures that the water is properly heated before entering the boiler, which helps maintain the efficiency and performance of the equipment.

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  • 42. 

    What type of draft system draws the required air through the equipment only?

    • A.

      Forced

    • B.

      Induced

    • C.

      Natural

    • D.

      Balanced

    Correct Answer
    B. Induced
    Explanation
    An induced draft system draws the required air through the equipment only. Unlike forced draft systems, which push air into the equipment, an induced draft system creates a negative pressure within the equipment, causing air to be drawn in. This type of system is commonly used in boilers and furnaces, where it helps to improve combustion efficiency and prevent the release of harmful gases.

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  • 43. 

    Which mechanical draft system is the most flexible?

    • A.

      Natural

    • B.

      Induced

    • C.

      Forced

    • D.

      Balanced

    Correct Answer
    D. Balanced
    Explanation
    A balanced mechanical draft system is the most flexible because it combines the features of both induced and forced draft systems. It uses a combination of fans to create a balanced air pressure within the system, allowing for more control over the airflow. This flexibility is important in various industrial applications where the airflow needs to be adjusted based on different operating conditions.

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  • 44. 

    Centrifugal fans are normally used in what type draft systems?

    • A.

      Balanced

    • B.

      Induced

    • C.

      Forced

    • D.

      Induced

    Correct Answer
    C. Forced
    Explanation
    Centrifugal fans are normally used in forced draft systems. Forced draft systems are designed to push air into a space or system, creating positive pressure. Centrifugal fans are particularly effective in these systems as they generate high airflow and pressure, allowing for efficient and controlled air movement. In contrast, induced draft systems use fans to pull air out of a space or system, creating negative pressure.

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  • 45. 

    Which fan drive is used if no electrical power is availiable?

    • A.

      Centrifugal

    • B.

      Reciprocating

    • C.

      Steam turbine

    • D.

      Electrical turbine

    Correct Answer
    C. Steam turbine
    Explanation
    A steam turbine is used when no electrical power is available. Steam turbines are driven by high-pressure steam generated by boilers, and they convert the thermal energy of the steam into mechanical energy to drive a fan or any other equipment. Since no electrical power is available, a steam turbine is a suitable option as it can operate independently without relying on external power sources.

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  • 46. 

    A compound Bourdon gauge can measure

    • A.

      Pressure and temperature

    • B.

      Vacuum and level

    • C.

      Pressure and vacuum

    • D.

      Temperature and level

    Correct Answer
    C. Pressure and vacuum
    Explanation
    A compound Bourdon gauge is a type of pressure gauge that is capable of measuring both pressure and vacuum. This is achieved by using two separate Bourdon tubes, one for measuring pressure and the other for measuring vacuum. The pressure tube is designed to expand under pressure, while the vacuum tube is designed to contract under vacuum. By combining the readings from both tubes, the gauge can accurately measure both positive and negative pressure values, making it suitable for applications where pressure and vacuum measurements are required.

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  • 47. 

    Manometers provide accurate measurements of low pressures from

    • A.

      0 to 50 psi

    • B.

      0 to 75 psi

    • C.

      0 to 100 psi

    • D.

      0 to 125 psi

    Correct Answer
    A. 0 to 50 psi
    Explanation
    Manometers are devices used to measure pressure, particularly low pressures. The given answer states that manometers provide accurate measurements of low pressures from 0 to 50 psi. This means that the manometer can accurately measure any pressure within the range of 0 to 50 psi.

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  • 48. 

    Pressure applied to the bellows in a bellows gauge causes the bellows to move

    • A.

      Upward

    • B.

      Outward

    • C.

      Downward

    • D.

      From side to side

    Correct Answer
    C. Downward
    Explanation
    When pressure is applied to the bellows in a bellows gauge, the air inside the bellows gets compressed. This compression causes the bellows to contract or move downward. As the bellows moves downward, it indicates an increase in pressure. Therefore, the correct answer is downward.

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  • 49. 

    The temperature measuring device the consists of a thermobulb, capillary tubing, and pressure indicating device is a 

    • A.

      Thermocouple

    • B.

      Bimetallic thermometer

    • C.

      Liquid-in-glass thermometer

    • D.

      Distant-reading dial thermometer

    Correct Answer
    D. Distant-reading dial thermometer
    Explanation
    A distant-reading dial thermometer is a temperature measuring device that consists of a thermobulb, capillary tubing, and a pressure indicating device. This type of thermometer allows for temperature measurement from a distance, as the dial displays the temperature reading. The thermobulb captures the temperature, which is then transmitted through the capillary tubing to the pressure indicating device, which in turn displays the temperature on the dial. This allows for easy and convenient temperature measurement without the need for direct contact with the object or environment being measured.

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  • 50. 

    Pressure controllers on steam boilers are always mounted

    • A.

      Above a pressure gauge

    • B.

      Below a pressure gauge

    • C.

      Above the water line

    • D.

      Below the water line

    Correct Answer
    C. Above the water line
    Explanation
    Pressure controllers on steam boilers are always mounted above the water line to ensure accurate pressure measurement and control. Placing them above the water line prevents any interference or obstruction caused by the water level fluctuations, which could affect the accuracy of the pressure readings. Additionally, mounting them above the water line also helps in preventing any damage or malfunction due to contact with water or steam.

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Quiz Review Timeline +

Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.

  • Current Version
  • Mar 21, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Mar 04, 2012
    Quiz Created by
    Enorab
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