Maryland Engineer 3rd Class Test

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  • 1/82 Questions

    Boilers that have hot gases circulation through tubes surrounded by water are called

    • Firetube boilers
    • High pressure boilers
    • Low pressure boilers
    • Low-boy air
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About This Quiz

This quiz tests knowledge essential for a Maryland Engineer 3rd Class, focusing on steam systems, heating mechanics, and safety precautions.

Maryland Engineer 3rd Class Test - Quiz

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  • 2. 

    A volute is part of a?

    • Centrifugal pump

    • Gear pump

    • Hose pump

    • Plunger pump

    Correct Answer
    A. Centrifugal pump
    Explanation
    A volute is a part of a centrifugal pump. It is a curved casing that converts the kinetic energy of the fluid into pressure energy. The volute is responsible for directing the flow of fluid from the impeller to the discharge pipe. It helps to increase the efficiency of the pump by reducing turbulence and increasing the pressure of the fluid. In centrifugal pumps, the volute is a crucial component that plays a significant role in the pump's overall performance.

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  • 3. 

    In all steam heating systems, the vertical steam supply pipes are called?

    • Riser

    • Returns

    • Upfeeds

    • Wet lines

    Correct Answer
    A. Riser
    Explanation
    In steam heating systems, the vertical steam supply pipes are referred to as risers. These pipes carry the steam from the boiler to the upper floors or radiators of a building. The term "riser" is used because these pipes rise vertically, allowing the steam to flow upwards and distribute heat throughout the system.

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  • 4. 

    The smallest type of expansion tank is the 

    • Diaphragm expansion tank

    • Open expansion tank

    • Closed expansion tank

    • Conventional expansion tank

    Correct Answer
    A. Diaphragm expansion tank
    Explanation
    A diaphragm expansion tank is the smallest type of expansion tank. It is designed with a flexible diaphragm that separates the air and water inside the tank. This diaphragm allows for the expansion of water as it heats up, preventing excessive pressure buildup in the system. The compact size of the diaphragm expansion tank makes it ideal for smaller spaces or applications where space is limited.

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  • 5. 

    (Fill in the blanks) The CBS low-pressure heating boiler has failed. Without even checking it, the facility manager Todd believes he knows the reason, as the most common cause of such failures is overheating of the ___ surface resulting from a ___ water

    • Heating, low

    • Heating, high

    • Cooling, high

    • Cooling, low

    Correct Answer
    A. Heating, low
    Explanation
    The most common cause of low-pressure heating boiler failures is overheating of the heating surface resulting from low water heating. Todd, the facility manager, believes this is the reason for the CBS boiler failure without even checking it.

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  • 6. 

    [The formula for the area of a circle is?  ]

    • 2 x π x R

    • π x R2 x 2

    • π x R2 

    Correct Answer
    A. π x R2 
    Explanation
    The formula for the area of a circle is π x R^2. This formula is derived from the relationship between the radius (R) of a circle and its area. The area of a circle is equal to the product of π (pi) and the square of the radius (R) squared. This formula is widely accepted and used in mathematics and geometry to calculate the area of a circle.

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  • 7. 

    A boiler is producing 40,000 lb of steam at a pressure of 100 psi and a steam temperature of 500 deg F. The steam produces is ___________ 

    • Supersaturate 

    • Desuperheated 

    • Superheated 

    • Saturated

    Correct Answer
    A. Superheated 
    Explanation
    The given information states that the boiler is producing steam at a pressure of 100 psi and a temperature of 500 deg F. Since the steam is produced at a temperature higher than its saturation temperature at the given pressure, it is considered superheated. Superheated steam is steam that has been heated above its saturation temperature, resulting in higher energy content and temperature compared to saturated steam.

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  • 8. 

    A deposit of scale or mud in an HRT boiler could cause

    • A bag to develop 

    • A draft loss 

    • Overheating of the breeching 

    • Lowering of the chimney temperature 

    Correct Answer
    A. Overheating of the breeching 
    Explanation
    A deposit of scale or mud in an HRT boiler could cause overheating of the breeching. Scale or mud deposits can restrict the flow of water and heat in the boiler, leading to an increase in temperature in the breeching. This overheating can be dangerous and may result in damage to the breeching or other components of the boiler system. It is important to regularly clean and maintain the boiler to prevent the formation of scale or mud deposits and ensure safe and efficient operation.

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  • 9. 

    Waterfall tubes protect the refractory and  

    • Increase boiler heating surface  

    • Act as a stay for tube sheets 

    • Allow the operator to blow down while steaming 

    • Option 4

    Correct Answer
    A. Increase boiler heating surface  
    Explanation
    Waterfall tubes increase the boiler heating surface. The addition of these tubes provides more surface area for heat transfer, allowing for greater efficiency in the boiler's operation. This is beneficial as it helps to maximize the heat transfer and improve the overall performance of the boiler. By increasing the heating surface, the boiler can generate more steam and meet the required steam demand more effectively.

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  • 10. 

    One of the largest potential energy wasters in a steam distribution system is:

    • Leaking steam traps

    • Faulty throttling valves

    • Air in the system

    • Uninsulated condensate lines

    Correct Answer
    A. Leaking steam traps
    Explanation
    Leaking steam traps can be a significant potential energy waster in a steam distribution system. Steam traps are used to remove condensate from the steam system, but when they leak, they allow live steam to escape. This leads to a loss of energy and can result in higher energy costs. By identifying and repairing these leaks, the system can operate more efficiently and reduce energy waste.

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  • 11. 

    The boiler operator should watch at all times for all of the following except?

    • Leaks in steam, water, and fuel connections

    • Proper fuel air ratio

    • Operating pressure and temperatures

    • Incoming water quality

    Correct Answer
    A. Incoming water quality
    Explanation
    The boiler operator should watch at all times for leaks in steam, water, and fuel connections to ensure that there are no potential safety hazards or wastage of resources. They should also monitor the proper fuel air ratio to maintain efficient combustion and prevent any issues related to incomplete or excessive burning. Additionally, the operator needs to keep an eye on operating pressure and temperatures to ensure that they are within safe and optimal limits. However, incoming water quality is not directly related to the operation and performance of the boiler, so it is not necessary for the operator to constantly monitor it.

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  • 12. 

    Three boilers are connected to a common header and each boiler is carrying 100 psi. The pressure gauge on the header reads _____psi.

    • 100

    • 200

    • 300

    • 400

    Correct Answer
    A. 100
    Explanation
    The pressure gauge on the header reads 100 psi because each boiler is carrying 100 psi and they are all connected to a common header. Therefore, the pressure in the header would be the same as the pressure in each individual boiler, which is 100 psi.

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  • 13. 

    (Fill in the Blank) Seamus needs to check the steam system at the point where the pressure is the highest. He should check _____ where the heat is ___?

    • Boiler; added

    • Boiler; removed

    • Radiator; added

    • Radiator; removed

    Correct Answer
    A. Boiler; added
    Explanation
    Seamus needs to check the steam system at the point where the pressure is the highest. He should check the boiler where the heat is added.

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  • 14. 

    Two types of electric boilers are the electrode and the?

    • Immersion

    • Modified Scotch

    • Steel plate

    • Tubular

    Correct Answer
    A. Immersion
    Explanation
    The correct answer is "immersion" because it is mentioned as one of the two types of electric boilers in the question. The other type mentioned is the electrode, indicating that "immersion" is the missing option.

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  • 15. 

    Watertube boilers require less water than _____ boilers

    • Firetube boiler

    • Industrial watertube

    • Scotch marine

    • None of the above

    Correct Answer
    A. Firetube boiler
    Explanation
    Watertube boilers require less water than firetube boilers because in a firetube boiler, the hot gases pass through the tubes and the water surrounds them. This design requires a larger volume of water to be heated. In contrast, in a watertube boiler, the water flows inside the tubes while the hot gases surround them. This design allows for a smaller volume of water to be heated, making watertube boilers more efficient in terms of water usage. Industrial watertube and scotch marine boilers are specific types of watertube boilers, so they also require less water compared to firetube boilers.

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  • 16. 

    A packing-type seal is designed to leak a small amount of liquid through the packing to?

    • Lubricate and cool the packing

    • Relieve system pressure

    • Check temperature of fluids

    • Keep air out of the system

    Correct Answer
    A. Lubricate and cool the packing
    Explanation
    A packing-type seal is designed to leak a small amount of liquid through the packing to lubricate and cool the packing. This is important because the packing, which is used to create a seal between moving parts, can generate heat and friction during operation. By allowing a small amount of liquid to leak through the packing, it helps to reduce friction and heat buildup, ensuring the longevity and efficiency of the seal.

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  • 17. 

    What is 60°C on the Fahrenheit scale?

    • 145°

    • 40°

    • 140°

    • 48°

    Correct Answer
    A. 140°
    Explanation
    To convert Celsius to Fahrenheit, you can use the formula F = (C x 9/5) + 32. Plugging in 60 for C, the calculation would be (60 x 9/5) + 32 = 140. Therefore, 60°C is equal to 140°F on the Fahrenheit scale.

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  • 18. 

    You have been told that the cost of heating oil is increasing by 4%. If the current cost of oil is $1.04, the new price will be:

    • $1.43

    • $1.16

    • 1.08

    • 1.04

    Correct Answer
    A. 1.08
    Explanation
    The cost of heating oil is increasing by 4% of the current price. To find the new price, we need to add 4% of $1.04 to $1.04. 4% of $1.04 is $0.0416. Adding this to $1.04 gives us $1.0816, which can be rounded to $1.08. Therefore, the new price of heating oil will be $1.08.

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  • 19. 

    ( Fill in the blank) A silver spoon placed in hot coffee quickly becomes too hot to handle. The spoon is heated by__?

    • Conduction

    • Convection

    • Radiation

    • None of the above

    Correct Answer
    A. Conduction
    Explanation
    The silver spoon placed in hot coffee becomes too hot to handle because of conduction. Conduction is the transfer of heat through direct contact between two objects. In this case, the hot coffee transfers its heat energy to the spoon through direct contact, causing the spoon to heat up.

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  • 20. 

    Steam at 250 psia and 400°F is considered ____ 

    • Supersaturated

    • Saturated

    • Superheated

    • Steam temperature cannot exceed 212°F 

    Correct Answer
    A. Superheated
    Explanation
    Steam at 250 psia and 400°F is considered superheated because it is above its saturation temperature at that pressure. Superheated steam is steam that has been heated to a temperature higher than its boiling point at the given pressure. In this case, the boiling point of water at 250 psia is below 400°F, so the steam is in a superheated state.

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  • 21. 

    _____ boilers can operate at higher pressures than firetube boilers

    • HRT

    • Scotch Maring

    • Vertical Firetube

    • Watertube

    Correct Answer
    A. Watertube
    Explanation
    Watertube boilers can operate at higher pressures than firetube boilers because they have a design that allows for the circulation of water inside the tubes, which helps in absorbing heat more efficiently. This design also allows for a larger surface area for heat transfer, enabling the boiler to handle higher pressure levels. In contrast, firetube boilers have water surrounding the tubes, which limits their ability to handle high pressures. Therefore, watertube boilers are better suited for applications that require higher pressure operations.

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  • 22. 

    If a pump sounds like it is pumping gravel, the most likely problem is?

    • Lack of balance

    • Worn bearings

    • Loose couplings

    • Cavitation

    Correct Answer
    A. Cavitation
    Explanation
    Cavitation is the most likely problem when a pump sounds like it is pumping gravel. Cavitation occurs when the pressure in the pump drops to a level where the liquid being pumped vaporizes and forms bubbles. These bubbles then collapse violently, causing a noise similar to pumping gravel. Cavitation can damage the pump and reduce its efficiency, so it is important to address this issue promptly.

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  • 23. 

    A thermocouple used to detect the presence of a gas flame consists of?

    • An infrared ray-emitting device

    • A rod extending into the flame

    • An ultraviolet ray-emitting device

    • Two wires of dissimilar metal welded together

    Correct Answer
    A. Two wires of dissimilar metal welded together
    Explanation
    A thermocouple used to detect the presence of a gas flame consists of two wires of dissimilar metal welded together. When the flame is present, it heats up the junction of the two metals, creating a temperature difference. This temperature difference generates a small electric voltage, known as the thermoelectric effect. This voltage is then used to detect the presence of the flame and can be used to control the gas supply accordingly. The infrared and ultraviolet ray-emitting devices mentioned are not directly related to the functioning of a thermocouple in detecting a gas flame.

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  • 24. 

    The metric to USCS conversion factor for meters to feet is 3.281 Convert 20 meters to feet

    • 164.0 ft.

    • 72.9 ft.

    • 65.6 ft.

    • 6.1 ft.

    Correct Answer
    A. 65.6 ft.
    Explanation
    The correct answer is 65.6 ft. To convert meters to feet, we multiply the length in meters by the conversion factor of 3.281. Therefore, 20 meters multiplied by 3.281 equals 65.6 feet.

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  • 25. 

    A pump affects the pressure of a fluid or gas by?

    • Raising pressure

    • Reducing pressure

    • Regulating pressure

    • Stabilizing pressure

    Correct Answer
    A. Raising pressure
    Explanation
    A pump affects the pressure of a fluid or gas by raising it. When a pump is activated, it creates a higher pressure in the system by increasing the energy of the fluid or gas. This is typically achieved by using mechanical force to push the fluid or gas into a confined space, which in turn increases the pressure. As a result, the pump is able to raise the pressure of the fluid or gas to the desired level for various applications such as pumping water to higher elevations or increasing the pressure in a hydraulic system.

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  • 26. 

    The steam boiler component used to lower the concentration of dissolved impurities in the boiler water is?

    • Blow-off connection

    • Deconcentrator

    • Feed connection

    • Sediment reduction valve

    Correct Answer
    A. Blow-off connection
    Explanation
    A blow-off connection is a steam boiler component that is used to lower the concentration of dissolved impurities in the boiler water. It allows for the removal of accumulated sediment and dissolved solids from the boiler, helping to maintain the water quality and prevent damage to the boiler system. By opening the blow-off connection, the impurities are discharged from the boiler, ensuring that the water remains clean and free from excessive contaminants.

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  • 27. 

    The most common cause of feeder or low-water fuel cut-off trouble is the operator's failure to observe the?

    • Blow-down instructions

    • Fuel calibration sequence

    • Water treatment limitations

    • Low-water control calibration

    Correct Answer
    A. Blow-down instructions
    Explanation
    The most common cause of feeder or low-water fuel cut-off trouble is the operator's failure to observe the blow-down instructions. Blow-down instructions refer to the process of removing sediment or impurities from the fuel system by draining a small amount of water or fuel. Failure to follow these instructions can lead to blockages or build-up of contaminants in the system, affecting its performance and causing trouble with the feeder or low-water fuel cut-off.

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  • 28. 

    What number do you use to find Rankin from Fahrenheit?

    • +273

    • + 460

    • -273

    • -460

    Correct Answer
    A. + 460
    Explanation
    To convert Fahrenheit to Rankin, you need to add 460. Rankin is a temperature scale that is similar to Fahrenheit, but starts at absolute zero, which is -460 degrees Fahrenheit. Therefore, to find Rankin from Fahrenheit, you add 460.

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  • 29. 

    When steam or hot water is used as the heat source in a secondary warm air heating system, the system may be classified as a?

    • Direct-fired boiler

    • Fin-coil heat exchanger

    • Vertical forced air

    • Low-boy air

    Correct Answer
    A. Fin-coil heat exchanger
    Explanation
    When steam or hot water is used as the heat source in a secondary warm air heating system, the system may be classified as a fin-coil heat exchanger. A fin-coil heat exchanger is a type of heat exchanger that consists of a coil with fins attached to it. The steam or hot water flows through the coil, transferring heat to the fins, which in turn transfer the heat to the air passing over them. This heated air is then distributed throughout the space using a forced air system. The use of a fin-coil heat exchanger allows for efficient heat transfer and effective heating of the air in the secondary warm air heating system.

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  • 30. 

    The most common type of firetube boiler used for heating large buildings is the?

    • Cast-iron

    • High pressure

    • Modified Scotch

    • Modular

    Correct Answer
    A. Modified Scotch
    Explanation
    A modified Scotch firetube boiler is the most common type of firetube boiler used for heating large buildings. This type of boiler is designed with a large volume of water and a long path for the hot gases to travel, allowing for efficient heat transfer. It is commonly used in heating systems for its reliability, durability, and ability to handle high pressures. The modified Scotch design incorporates improvements and modifications to the traditional Scotch boiler, making it even more suitable for heating large buildings.

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  • 31. 

    The unit of measurement a compound pressure gauge uses to measure pressures below atmospheric pressure is?

    • Inches of mercury

    • Inches of water

    • Pounds per square inch

    • Pounds per square inch gauge

    Correct Answer
    A. Inches of mercury
    Explanation
    A compound pressure gauge uses inches of mercury as the unit of measurement to measure pressures below atmospheric pressure. This unit is commonly used in applications such as vacuum systems and barometers. Inches of mercury refers to the height of a column of mercury in a tube, which is used to indicate the pressure. As the pressure decreases below atmospheric pressure, the height of the mercury column also decreases. Therefore, inches of mercury is the appropriate unit for measuring pressures below atmospheric pressure.

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  • 32. 

    Routine operation and maintenance of a hydronic heating system should include all the following except?

    • Confirming that automatic air vents are functional

    • Checking level of air cushion in expansion tank

    • Lubrication pump motors

    • Lubrication condensate pump

    Correct Answer
    A. Lubrication condensate pump
    Explanation
    Routine operation and maintenance of a hydronic heating system should include confirming that automatic air vents are functional, checking the level of air cushion in the expansion tank, and lubricating pump motors. However, lubricating the condensate pump is not necessary as it does not require regular lubrication.

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  • 33. 

    To reduce corrosion in large hydronic heating systems, a gas cushion is recommended in the expansion tank consisting of?

    • Oxygen

    • Hydrogen

    • Nitrogen

    • Soluble gas

    Correct Answer
    A. Nitrogen
    Explanation
    Nitrogen is recommended as a gas cushion in the expansion tank of large hydronic heating systems to reduce corrosion. Nitrogen is an inert gas that does not react with other substances, making it ideal for preventing oxidation and corrosion. By filling the expansion tank with nitrogen, it creates a protective barrier that helps to minimize the contact between the water and metal surfaces, reducing the chances of corrosion occurring.

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  • 34. 

    The control used on gas and oil fired heating boilers to provide for proper sequencing of the combustion controls during the startup and shutdown is the?

    • Limit control

    • Capacity control

    • Programming control

    • Safety control

    Correct Answer
    A. Programming control
    Explanation
    The programming control is used on gas and oil fired heating boilers to ensure proper sequencing of the combustion controls during startup and shutdown. This control is responsible for programming and coordinating the various functions and operations of the boiler system, ensuring that the combustion controls are activated in the correct order and at the appropriate times. It helps in optimizing the efficiency and safety of the boiler by controlling the fuel supply, ignition, and shutdown processes.

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  • 35. 

    A dry piper separator

    • Delivers higher quality steam to the header 

    • Distributes feedwater the length of the drum 

    • Prevents water hammer 

    • Agitates the water in the steam and water drum   

    Correct Answer
    A. Delivers higher quality steam to the header 
    Explanation
    A dry piper separator delivers higher quality steam to the header by removing any remaining moisture or water droplets from the steam. This ensures that only dry steam is delivered to the header, which is important for the efficient operation of steam systems. Dry steam helps to prevent corrosion, erosion, and damage to equipment downstream. It also improves the overall performance and effectiveness of the steam system.

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  • 36. 

    The device that ensures that steam pressure will not force the boiler water back into the return line is a?

    • Condensate trap

    • Direct feed pump

    • Hartford loop

    • Pressure regulator

    Correct Answer
    A. Hartford loop
    Explanation
    A Hartford loop is a device that ensures that steam pressure does not force the boiler water back into the return line. It is a piping arrangement that creates a loop in the steam supply and return lines, allowing condensate to collect and drain back into the boiler. This prevents water hammer and damage to the boiler by keeping the water separate from the steam.

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  • 37. 

    The type of ventilation system that forces fresh air into the building by a fan and moves stale air out through outlets in outside walls or the roof is called?

    • Forced air 

    • Makeup ventilation

    • Natural balancing pressure

    • Mechanical air intake/natural exhaust

    Correct Answer
    A. Mechanical air intake/natural exhaust
    Explanation
    The correct answer is mechanical air intake/natural exhaust. This type of ventilation system uses a fan to bring fresh air into the building and allows stale air to exit through outlets in the outside walls or roof. It combines mechanical air intake with natural exhaust to ensure proper air circulation and maintain indoor air quality.

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  • 38. 

    What number do you use to find Kelvin from Celsius?

    • +273

    • -273

    • +460

    • -460

    Correct Answer
    A. +273
    Explanation
    To convert Celsius to Kelvin, you need to add 273. This is because the Kelvin scale starts at absolute zero, which is -273 degrees Celsius. Therefore, adding 273 to any Celsius temperature will give you the equivalent temperature in Kelvin.

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  • 39. 

    There 33,000 ft-lb min in mechanical horsepower. What is the equivalent in Btu?

    • 42.4 BTU

    • 42.1 BTU

    • 24.8 BTU

    • 40.4 BTU

    Correct Answer
    A. 42.4 BTU
  • 40. 

    All of the following boiler fitting are required on hot water heating boilers except?

    • A pressure or altitude gauge

    • A safety relief valve

    • A shut-off valve

    • A water gauge glass and column

    Correct Answer
    A. A water gauge glass and column
    Explanation
    A water gauge glass and column is not required on hot water heating boilers. This is because hot water heating boilers do not require a visual indicator to measure the water level, unlike steam boilers. The other options listed (pressure or altitude gauge, safety relief valve, shut-off valve) are all necessary components for the safe and efficient operation of hot water heating boilers.

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  • 41. 

    The scale on a pressure gauge dial should be graduated with a range up to?

    • 1 1\2 to 3 times the working pressure

    • The maximum working pressure 

    • 5 times the working pressure 

    • 1\2 the working pressure

    Correct Answer
    A. 1 1\2 to 3 times the working pressure
    Explanation
    The scale on a pressure gauge dial should be graduated with a range up to 1 1/2 to 3 times the working pressure. This is because the pressure gauge needs to have a sufficient range to accurately measure the pressure fluctuations within the system. Graduating the scale with a range that is 1 1/2 to 3 times the working pressure allows for variations in pressure without exceeding the maximum limit of the gauge. This range ensures that the gauge can effectively monitor and display the pressure levels within the desired range.

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  • 42. 

    Four basic systems found on boilers

    • Steam, feed water, fuel, and draft

    • Steam, exhaust, fuel, and draft

    • Steam, fuel, condensate, and blowdown

    • Steam, condensate, draft, and exhaust

    Correct Answer
    A. Steam, feed water, fuel, and draft
    Explanation
    The correct answer is steam, feed water, fuel, and draft. These four basic systems are essential components found on boilers. Steam is produced by heating the water, feed water is the water that is supplied to the boiler, fuel is the source of heat that is used to produce steam, and draft refers to the flow of air or gases through the boiler. These systems work together to ensure the efficient operation of the boiler and the production of steam.

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  • 43. 

    Feed water temperature raised 10°F from exhaust steam of heat from gases of combustion results in an increase of _____ % in plant efficiency

    • O

    • 1

    • 5

    • 10

    Correct Answer
    A. 1
    Explanation
    Raising the feed water temperature by 10°F from the exhaust steam of heat from gases of combustion results in a 1% increase in plant efficiency. This indicates that even a small increase in feed water temperature can have a positive impact on the efficiency of the plant.

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  • 44. 

    _________ What 3 things are necessary for complete combustion

    • Forced draft, turbelence, and heat

    • Fuel oil, air, time, and mixture

    • Time, temperature, mixture, and atomization

    • Time, temperature, and draft

    Correct Answer
    A. Time, temperature, and draft
    Explanation
    Complete combustion requires three things: time, temperature, and draft. Time is necessary to allow the fuel to fully burn, temperature is needed to reach the ignition point of the fuel, and draft is required to provide the necessary oxygen for the combustion process. Without any of these three factors, complete combustion cannot occur.

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  • 45. 

    The greatest benefit of the dry method of laying up a boiler is it?

    • Prevents freezing

    • Minimizes corrosion

    • Minimizes oxidation

    • Eliminates off-season leaking

    Correct Answer
    A. Prevents freezing
    Explanation
    The dry method of laying up a boiler prevents freezing. This is because during the dry method, all the water is drained from the boiler, leaving no liquid to freeze and potentially cause damage to the system. By preventing freezing, the dry method helps to ensure the longevity and proper functioning of the boiler.

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  • 46. 

    Trimming an impeller should result in a?

    • Reduction of noise

    • Decrease of power consumption

    • Improvement of a cavitation problem

    • Increase in pump horsepower

    Correct Answer
    A. Decrease of power consumption
    Explanation
    Trimming an impeller involves removing material from the impeller blades, which can result in a decrease in power consumption. By reducing the weight and size of the impeller, it requires less energy to rotate, resulting in a decrease in power consumption. Trimming can help optimize the impeller's performance and improve the efficiency of the pump system, leading to energy savings.

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  • 47. 

    If a 20-tooth pinion is turning at 120rpm and the driven gear has 60 teeth, the driven gear is turning at?

    • 1 rpm

    • 30rpm

    • 40 rpm

    • 360rpm

    Correct Answer
    A. 40 rpm
    Explanation
    The driven gear has 3 times as many teeth as the pinion gear. Therefore, for every 1 revolution of the pinion gear, the driven gear will make 1/3 of a revolution. Since the pinion gear is turning at 120rpm, the driven gear will turn at 1/3 of that speed, which is 40rpm.

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  • 48. 

    According to ASME code, when warming up a boiler the air cock is closed when

    • Steam starts to come out of the boiler 

    • The steam pressure gauge reads 25psi 

    • The steam pressure gauge reads 35psi 

    • The boiler goes on-line 

    Correct Answer
    A. The steam pressure gauge reads 25psi 
    Explanation
    According to the ASME code, when warming up a boiler, the air cock is closed when the steam pressure gauge reads 25psi. This indicates that the boiler has reached the desired pressure and is ready for operation. Closing the air cock at this point helps to ensure that the boiler is properly pressurized and ready to generate steam efficiently.

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  • 49. 

    Heat absorbed by water when changing from liquid to steam at the boiling point

    • Sensible heat

    • Latent heat

    • Specific heat

    • Superheat

    Correct Answer
    A. Latent heat
    Explanation
    Latent heat is the correct answer because when water changes from a liquid to steam at its boiling point, it absorbs heat without any change in temperature. This heat energy is used to break the intermolecular bonds between water molecules and convert them into a gaseous state. This process is known as vaporization and the heat absorbed during this phase change is called latent heat. Therefore, latent heat is the appropriate term to describe the heat absorbed by water during the phase change from liquid to steam at the boiling point.

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