3e151 B Set Vol 4

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  • 1/100 Questions

    A fan drive is an assembly made up of

    • A motor sheave, fan sheave, and connecting belts
    • Grooves used to increase and decrease the speed of the fan
    • Fixed bores that allow the sheaves to fit the shaft exactly
    • Movable discs to increase or decrease the pitch diameter
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Professional Certification Quizzes & Trivia
About This Quiz

The '3E151 B Set Vol 4' quiz assesses knowledge in air distribution systems, focusing on fan types, configurations, and maintenance. It covers centrifugal, axial fans, and V-belt inspections, crucial for professionals in HVAC and mechanical engineering.

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  • 2. 

    How many intakes does the single-suction pump impeller have?

    • One

    • Two

    • Three

    • Four

    Correct Answer
    A. One
    Explanation
    The single-suction pump impeller has only one intake. This means that there is only one opening or inlet through which the fluid is drawn into the impeller for pumping. Having only one intake allows for a more streamlined and efficient flow of the fluid, as it is directed towards a single point.

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  • 3. 

    After each major repair to a pump or when there is an indication that the system flow is not correct, what do you check?

    • Pump performance

    • Mechanical seals

    • Stuffing box

    • Bearings

    Correct Answer
    A. Pump performance
    Explanation
    After each major repair to a pump or when there is an indication that the system flow is not correct, it is important to check the pump performance. This involves evaluating various aspects such as the flow rate, pressure, efficiency, and power consumption of the pump. By checking the pump performance, any issues or abnormalities can be identified and addressed, ensuring that the pump is functioning optimally and the system flow is correct.

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  • 4. 

    The supply pressure loss data for equipment used in piping systems normally come from

    • Manufacturers

    • System designers

    • HVAC/R technicians

    • Velocity head pressure

    Correct Answer
    A. Manufacturers
    Explanation
    Manufacturers provide the supply pressure loss data for equipment used in piping systems. They have the necessary knowledge and expertise about their products to accurately determine the pressure loss associated with their equipment. System designers and HVAC/R technicians may also have some knowledge about pressure loss, but manufacturers are the primary source for this information as they design and produce the equipment. Velocity head pressure is not a source of supply pressure loss data; it is a term used to calculate the pressure loss in a piping system due to fluid velocity.

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  • 5. 

    Exposing an orginal and a translucent tracing paper to a strong light produces a copy with white lines on a blue background that is called 

    • A blueprint

    • An ozalid print

    • A director print

    • A photostat

    Correct Answer
    A. A blueprint
    Explanation
    When an original and a translucent tracing paper are exposed to a strong light, it creates a copy with white lines on a blue background. This copy is commonly known as a blueprint.

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  • 6. 

    Some leakage at the packing gland of a pump is needed to

    • Equalize the pressure on the two sides of the seal

    • Seal undesirable leakage to the stuffing box

    • Allow the coupling halves to be disconnected

    • Lubricate and cool the area between the material and shaft

    Correct Answer
    A. Lubricate and cool the area between the material and shaft
    Explanation
    The leakage at the packing gland of a pump is needed to lubricate and cool the area between the material and shaft. This is because the packing gland creates a seal around the shaft to prevent leakage, but a small amount of leakage is necessary to ensure that the area between the material being pumped and the shaft is properly lubricated and cooled. This helps to prevent friction and heat buildup, which can damage the pump and reduce its efficiency.

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  • 7. 

    Pumps with mechanical seals 

    • Can be run dry, depending on the ambient temperature

    • Can be run dry, depending on the internal pressure

    • Must not be run dry

    • Must be run dry

    Correct Answer
    A. Must not be run dry
    Explanation
    Pumps with mechanical seals must not be run dry because the seals require the presence of fluid to maintain lubrication and prevent overheating. Running the pump without any fluid can lead to damage or failure of the seals, causing leaks and potential damage to the pump itself. Therefore, it is important to ensure that these types of pumps are always operated with sufficient fluid to prevent dry running.

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  • 8. 

    What do manufacturers use to show how pumps respond under different operating condidtions?

    • Curves of system pressure changes for different altitudes

    • Curves of the temperature and pressure limitations

    • A graph of net positive suction pressure head curves

    • A performance curve graph

    Correct Answer
    A. A performance curve graph
    Explanation
    Manufacturers use a performance curve graph to show how pumps respond under different operating conditions. This graph represents the relationship between the pump's flow rate and the head it can generate. It provides valuable information about the pump's efficiency, power consumption, and operating range. By analyzing the performance curve, manufacturers can determine the pump's suitability for specific applications and make informed decisions about its operation and maintenance.

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  • 9. 

    Before you clean a HVAC coil, what should you do to the ducts in and out of the coil?

    • Nothing

    • Isolate them

    • Clean them with hot water

    • Flush them with cold water

    Correct Answer
    A. Isolate them
    Explanation
    Before cleaning a HVAC coil, it is important to isolate the ducts in and out of the coil. This is necessary to prevent any dirt, debris, or contaminants from entering the duct system during the cleaning process. By isolating the ducts, it ensures that the cleaning is focused solely on the coil and does not spread any pollutants throughout the ventilation system.

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  • 10. 

    For a heating steam coil to operate properly, eleminate

    • Supply and return on opposite ends

    • Distribution plates in the headers

    • Individual orifices in the tubes

    • All noncondensables

    Correct Answer
    A. All noncondensables
    Explanation
    To ensure the proper operation of a heating steam coil, it is necessary to eliminate all noncondensables. Noncondensables refer to gases or air trapped within the steam system that do not condense into water. These noncondensables can cause various issues such as reduced heat transfer efficiency, increased pressure drop, and potential damage to the coil. By removing all noncondensables, the steam coil can function optimally, allowing for efficient heat transfer and preventing any potential problems associated with the presence of noncondensables.

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  • 11. 

    What is the formula for calculating the volume of airflow through a duct?

    • Cfm = area x velocity

    • Area = cfm x velocity

    • Velocity = cfm x area

    • Standard air = cfm x area

    Correct Answer
    A. Cfm = area x velocity
    Explanation
    The formula for calculating the volume of airflow through a duct is cfm = area x velocity. This formula states that the airflow in cubic feet per minute (cfm) is equal to the product of the cross-sectional area of the duct and the velocity of the airflow. This formula allows for the determination of the volume of air passing through a duct based on its dimensions and the speed at which the air is flowing.

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  • 12. 

    What are the width and inlet constructions of centrifugal fans?

    • SWSI and DWDI

    • SWDI and DWSI

    • SPST and DPDT

    • SPDT and DPST

    Correct Answer
    A. SWSI and DWDI
    Explanation
    The correct answer is SWSI and DWDI. SWSI stands for Single Width Single Inlet, which means that the fan has a single inlet and a single width. DWDI stands for Double Width Double Inlet, which means that the fan has double inlets and a double width. These terms are used to describe the construction of centrifugal fans and indicate the number of inlets and the width of the fan.

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  • 13. 

    The most common size of V-belts used in HVAC systems are

    • 1L, 2L, and 3L

    • 3L, 4L, and 5L

    • A through D

    • A and B

    Correct Answer
    A. A through D
    Explanation
    The correct answer is A through D. This means that the most common size of V-belts used in HVAC systems can vary and include sizes ranging from A to D. The specific size of the V-belt used would depend on the requirements of the HVAC system and the manufacturer's recommendations.

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  • 14. 

    A single-duct system become a low-pressure reheat system when

    • A higher-pressure duct design and pressure reduction devices are used to permit system balancing

    • Heating coils are inserted into the duct system downstream of the cooling coils

    • The system responds to only one set of space conditions

    • Excess air is dumped into a return-air ceiling plenum

    Correct Answer
    A. Heating coils are inserted into the duct system downstream of the cooling coils
    Explanation
    When heating coils are inserted into the duct system downstream of the cooling coils, it means that the system has the capability to provide both cooling and heating functions. This is because the cooling coils are located before the heating coils in the airflow path. By having this setup, the system can adjust the temperature of the air as needed, making it a low-pressure reheat system.

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  • 15. 

    What is one way to reduce energy costs if a dual-duct system with no cooling load?

    • Replace existing boxes with high-pressure boxes

    • Operate the system as a single-zone

    • Operate the system as a multizone

    • Eliminate the return-air fan

    Correct Answer
    A. Operate the system as a single-zone
    Explanation
    Operating the system as a single-zone can help reduce energy costs in a dual-duct system with no cooling load because it allows for the elimination of unnecessary equipment and reduces the amount of energy required to operate the system. In a single-zone operation, both the supply and return air are mixed together and distributed throughout the building, eliminating the need for separate zones and the associated equipment and energy consumption. This can result in significant energy savings and cost reduction.

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  • 16. 

    When lubricating unit ventilator fan and motor bearings, you should?

    • Disconnect the motor

    • Remove the squirrel cage

    • Check the temperature drop

    • Follow the manufacturers's recommendations

    Correct Answer
    A. Follow the manufacturers's recommendations
    Explanation
    When lubricating unit ventilator fan and motor bearings, it is important to follow the manufacturer's recommendations. The manufacturer's recommendations will provide specific instructions on the type of lubricant to use, the frequency of lubrication, and any other important considerations. Following these recommendations ensures that the bearings are properly lubricated, which helps to reduce friction and wear, extend the lifespan of the bearings, and maintain the efficiency and performance of the unit ventilator fan and motor.

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  • 17. 

    Destructive pitting and wearing of a pump impeller and casing as well as noise and vibration can be caused

    • Cavitation

    • Friction loss

    • Stratification

    • Flow coefficient

    Correct Answer
    A. Cavitation
    Explanation
    Cavitation is the correct answer because it refers to the formation of vapor bubbles in a liquid due to low pressure, which then collapse and cause damage to the impeller and casing of a pump. This phenomenon can also result in noise and vibration. Friction loss, stratification, and flow coefficient do not directly cause these issues.

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  • 18. 

    Because the pressure in the hot and cold ducts of a dual-duct terminal may vary over a wide pressure range due to the demand for the hot and cold air varying throughout the building, it is important to have

    • An inlet vane

    • A sound baffle

    • A pneumatic motor

    • An automatic airflow control device

    Correct Answer
    A. An automatic airflow control device
    Explanation
    In a dual-duct terminal system, the pressure in the hot and cold ducts can vary significantly due to the varying demand for hot and cold air in different parts of the building. To ensure proper control and regulation of the airflow in such a system, it is important to have an automatic airflow control device. This device can adjust the airflow based on the demand, maintaining a balanced and consistent airflow in both the hot and cold ducts. It helps in maintaining a comfortable indoor environment and efficient operation of the system.

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  • 19. 

    Final working drawing used as contract documents are

    • As-built drawings

    • Engineer's drawings

    • Architect's drawings

    • Mechanical drawings

    Correct Answer
    A. As-built drawings
    Explanation
    As-built drawings are the final working drawings used as contract documents. These drawings are created after the completion of a construction project and accurately represent the actual conditions of the project as it was built. They provide detailed information about the dimensions, locations, and specifications of all the components and systems in the project. As-built drawings are essential for future reference, maintenance, and renovations as they reflect any changes or modifications made during the construction process.

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  • 20. 

    All low points on hydronic systems should be equipped with

    • Vents

    • Drains

    • Stutoffs

    • Strainers

    Correct Answer
    A. Drains
    Explanation
    All low points on hydronic systems should be equipped with drains. Drains are necessary to remove any accumulated water or condensation from the system. Without drains, water can build up in low points and cause damage to the system or create an environment for bacterial growth. Therefore, drains are essential to maintain the proper functioning and longevity of hydronic systems.

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  • 21. 

    When the condensate of a steam system has cooled below the condensing temperature, this is referred to as

    • Superheating

    • Subcooling

    • Saturated vapor

    • Enthalpy

    Correct Answer
    A. Subcooling
    Explanation
    When the condensate of a steam system has cooled below the condensing temperature, it is referred to as subcooling. Subcooling occurs when the temperature of the condensate is lower than its saturation temperature at the given pressure. This can happen when additional cooling is applied to the condensate after it has already reached its saturation point. Subcooling helps to ensure that the condensate remains in a liquid state, which is important for efficient heat transfer and preventing damage to equipment.

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  • 22. 

    The square feet of equivalent direct radiation (EDR) of a radiator depends upon radiator 

    • Location

    • Efficiency

    • Position

    • Capacity and configuration

    Correct Answer
    A. Capacity and configuration
    Explanation
    The square feet of equivalent direct radiation (EDR) of a radiator depends on its capacity and configuration. Capacity refers to the amount of heat that the radiator can produce, while configuration refers to the design and arrangement of the radiator's heating elements. Both factors play a crucial role in determining the EDR of a radiator. The capacity of the radiator determines the amount of heat it can emit, while the configuration affects the distribution and efficiency of the heat. Therefore, the EDR of a radiator is influenced by its capacity and configuration.

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  • 23. 

    When pressure-reducing valves are used in a steam system, what must also be used?

    • Relief devices

    • Mechanical traps

    • Inverted-bucket traps

    • Pilot-controlled valves

    Correct Answer
    A. Relief devices
    Explanation
    When pressure-reducing valves are used in a steam system, relief devices must also be used. This is because pressure-reducing valves only control the pressure in the system, but they do not provide protection against overpressure. Relief devices, such as safety valves or pressure relief valves, are necessary to prevent the pressure from exceeding safe limits and causing damage to the system or equipment. These devices automatically open and release excess pressure when it reaches a certain threshold, ensuring the safety and integrity of the steam system.

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  • 24. 

    Upon taking startup readings during equipment check out, one thing you should listen for is

    • The normal humming of the motor

    • Bursting or collapsing ducts

    • The sound of electricity

    • The sound of air

    Correct Answer
    A. Bursting or collapsing ducts
    Explanation
    During equipment check out, one should listen for bursting or collapsing ducts. This is important because if the ducts are damaged or compromised, it can affect the airflow and efficiency of the system. The sound of bursting or collapsing ducts can indicate potential issues that need to be addressed to ensure proper functioning of the equipment.

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  • 25. 

    The purpose of the vanes of a vaneaxial fan is to

    • Change the fpm

    • Change the cfm

    • Increase the torque

    • Straighten out the air's spiraling motion

    Correct Answer
    A. Straighten out the air's spiraling motion
    Explanation
    The purpose of the vanes of a vaneaxial fan is to straighten out the air's spiraling motion. Vaneaxial fans are designed to move large volumes of air at high pressures, and the vanes play a crucial role in achieving this. As the air enters the fan, it tends to spiral due to the rotational motion of the blades. The vanes are strategically placed to counteract this spiraling motion and straighten out the airflow. This ensures more efficient and effective airflow, allowing the fan to function optimally.

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  • 26. 

    What is the maximum allowable working pressure for low-pressure heating boilers with a maximum temperature limitations of 250*F?

    • 140 psi

    • 160 psi

    • 180 psi

    • 200 psi

    Correct Answer
    A. 160 psi
    Explanation
    The maximum allowable working pressure for low-pressure heating boilers with a maximum temperature limitation of 250°F is 160 psi. This means that the boiler can safely operate at a pressure of up to 160 pounds per square inch without risking damage or failure. It is important to adhere to these pressure limitations to ensure the safety and efficiency of the heating system.

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  • 27. 

    If air and other gases are not removed from the hydronic piping flow circuit, they may cause

    • Excessive air

    • Air binding

    • Vibration

    • Leakage

    Correct Answer
    A. Air binding
    Explanation
    Air binding occurs when air becomes trapped in the hydronic piping flow circuit and prevents the proper flow of water. This can lead to reduced efficiency and performance of the system, as well as potential damage to the components. It can cause blockages, reduce heat transfer, and create uneven distribution of water throughout the system. Therefore, it is important to remove air and other gases from the hydronic piping flow circuit to prevent air binding and ensure optimal operation.

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  • 28. 

    In air distributions systems, the three basic categories of fans are

    • Backward inclined, airfoil, and forward curve

    • Radial blade, centrifugal, and tubular inline

    • Centrifugal, special design, and axial

    • Propeller, tubeaxial, and vaneaxial

    Correct Answer
    A. Centrifugal, special design, and axial
    Explanation
    The correct answer is centrifugal, special design, and axial. In air distribution systems, centrifugal fans are commonly used due to their ability to generate high airflow and pressure. Special design fans are used for specific applications that require unique features such as explosion-proof or high-temperature resistance. Axial fans are typically used in situations where high airflow rates are needed at low pressure differentials, such as in cooling towers or ventilation systems.

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  • 29. 

    What is generally the proper tension for the top side of fan belts?

    • 1/2 to 1 inch deflection

    • 1/2 to 1 1/2 inch deflection

    • 3/4 to 1 1/4 inch deflection

    • 3/4 to 1 3/4 inch deflection

    Correct Answer
    A. 1/2 to 1 inch deflection
    Explanation
    The proper tension for the top side of fan belts is generally 1/2 to 1 inch deflection.

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  • 30. 

    What is normally the cause of vortex in a piping system?

    • Undersized piping

    • Too many fittings

    • Location of the pump

    • Configuration of the piping system

    Correct Answer
    A. Configuration of the piping system
    Explanation
    The configuration of the piping system refers to the layout and design of the pipes, including the angles, bends, and connections. A vortex in a piping system is typically caused by the improper configuration of the pipes, which leads to the formation of swirling or turbulent flow patterns. This can disrupt the smooth flow of fluid and cause issues such as pressure drops, cavitation, or even damage to the system. Therefore, it is important to ensure that the piping system is properly designed and configured to avoid vortex formation.

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  • 31. 

    Because it is necessary to keep a steam system in service at all times, what is installed around the automatic temperature control valve?

    • Dipped supply piping

    • Thermostatic traps

    • Steam mains

    • A bypass

    Correct Answer
    A. A bypass
    Explanation
    A bypass is installed around the automatic temperature control valve in order to keep the steam system in service at all times. This bypass allows the steam to flow even when the temperature control valve is closed or not functioning properly. It ensures that there is a continuous supply of steam to the system, preventing any disruptions or downtime.

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  • 32. 

    Normally, the basic central station HVAC equipment in the air/hydronic unit is located?

    • In each separate zone

    • Inside the conditioned space

    • Outside the conditioned space

    • With the heating and refrigeration equipment

    Correct Answer
    A. Outside the conditioned space
    Explanation
    The basic central station HVAC equipment is typically located outside the conditioned space. This is because the equipment, such as the heating and refrigeration units, needs to be housed in a separate area to prevent noise and heat transfer into the conditioned space. Additionally, locating the equipment outside allows for easier access for maintenance and repairs.

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  • 33. 

    The use of a retrun-air fan in central station unit is optional but generally is essential for proper operation of

    • Heat recovery

    • Larger systems

    • Smaller systems

    • Dehumidification

    Correct Answer
    A. Larger systems
    Explanation
    A return-air fan is optional but generally essential for larger systems in a central station unit. This is because larger systems require more airflow to properly circulate and condition the air in the space. The return-air fan helps to pull the air back into the unit, allowing for efficient operation and better control of temperature and humidity levels. In smaller systems, the airflow may be sufficient without the need for a return-air fan. However, in larger systems, the use of a return-air fan is recommended to ensure proper operation and performance.

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  • 34. 

    Which filter is recommended to remove very fine dust particles from the air?

    • Dry type

    • Fibrous media

    • Renewable media

    • Electronic air cleaner

    Correct Answer
    A. Electronic air cleaner
    Explanation
    An electronic air cleaner is recommended to remove very fine dust particles from the air. This type of filter uses an electronic charge to attract and capture particles as small as 0.1 microns, including fine dust particles. It is more effective in removing smaller particles compared to other filters like dry type, fibrous media, or renewable media.

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  • 35. 

    Which type of heat recovery equipment turns between 2 and 8 revolution per minute?

    • Counterflow

    • Heat pump

    • Heat wheel

    • Heat pipe

    Correct Answer
    A. Heat wheel
    Explanation
    A heat wheel is a type of heat recovery equipment that turns between 2 and 8 revolutions per minute. It consists of a rotating wheel with a honeycomb structure that allows for the transfer of heat between two air streams. As the wheel rotates, one side absorbs heat from the warm air stream while the other side releases heat to the cool air stream. This process helps to recover and transfer heat energy, making it an efficient method for heat recovery in HVAC systems.

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  • 36. 

    What would be the acceptable temperature and pressure of a chilled-water supply system, without an antifreeze additive?

    • 58*F and less than 125 psi

    • 58*F and greater that 125 psi

    • 48*F and less that 125 psi

    • 48*F and greater that 125 psi

    Correct Answer
    A. 48*F and less that 125 psi
    Explanation
    The acceptable temperature for a chilled-water supply system without an antifreeze additive is 48°F. This is because a lower temperature helps to prevent the growth of bacteria and other microorganisms in the water. The acceptable pressure should be less than 125 psi, as a higher pressure can put stress on the system and potentially cause leaks or damage.

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  • 37. 

    Which item is a three-way valve that has one input and two outputs?

    • Sequencing

    • Diverting

    • Butterfly

    • Mixing

    Correct Answer
    A. Diverting
    Explanation
    A diverting valve is a three-way valve that has one input and two outputs. This type of valve allows the flow of fluid to be diverted from the main input to either of the two outputs. It is commonly used in various applications where the flow needs to be redirected or split into two different paths. The sequencing valve is not the correct answer as it typically has multiple inputs and one output. The butterfly valve is also not the correct answer as it is a type of valve that controls the flow using a disc-shaped closure element. The mixing valve is also not the correct answer as it is used to blend two or more fluids together.

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  • 38. 

    Which multi-blade dampers use a linkage that causes the adjacent blades to move in opposite directions?

    • Parallel

    • Adjacent

    • Opposed

    • Volume

    Correct Answer
    A. Opposed
    Explanation
    Opposed multi-blade dampers use a linkage that causes the adjacent blades to move in opposite directions. This means that when one blade moves in a certain direction, the blade next to it moves in the opposite direction. This linkage system allows for precise control and adjustment of the dampers, ensuring efficient airflow regulation and temperature control in HVAC systems.

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  • 39. 

    Which option best describes a damper flow characteristic?

    • Comparison between damper size and airflow rate

    • Relationship between damper size and damper leaf position

    • Comparison between the percent a damper is open to the size of a duct

    • Relationship between the position of the damper and percent of air that flows through it

    Correct Answer
    A. Relationship between the position of the damper and percent of air that flows through it
    Explanation
    The correct answer describes the relationship between the position of the damper and the percent of air that flows through it. This means that as the position of the damper changes, the amount of air flowing through it also changes.

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  • 40. 

    In what ways are coils basically constructed?

    • Bare tube or pipe and extended surfaces

    • Serpentine arrangement and multipass

    • Flattened tube and secondary fin

    • Staggered tubes and primary fin

    Correct Answer
    A. Bare tube or pipe and extended surfaces
    Explanation
    Coils are basically constructed using bare tubes or pipes and extended surfaces. This means that the coils are made by using either a bare tube or pipe as the base and then adding extended surfaces to increase the heat transfer area. This construction allows for efficient heat transfer and is commonly used in various applications such as heat exchangers and refrigeration systems.

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  • 41. 

    The basic types of supply-air outlets are

    • Double deflection, high sidewall, perimeter mounted, and ceiling mounted

    • Perpendicular flow, parallel flow, multipattern, perforated face

    • Grilles, slot diffusers, ceiling diffusers, and air-distributing ceiling

    • Adjustable bar, fixed bar, stamped, and variable area

    Correct Answer
    A. Grilles, slot diffusers, ceiling diffusers, and air-distributing ceiling
    Explanation
    The correct answer is grilles, slot diffusers, ceiling diffusers, and air-distributing ceiling. These are the basic types of supply-air outlets that are commonly used in HVAC systems. Grilles are typically used for large open areas, slot diffusers provide a long and narrow air distribution, ceiling diffusers are mounted in the ceiling and distribute air in a circular pattern, and air-distributing ceilings are designed to provide a uniform air distribution throughout the room. These different types of outlets allow for flexibility in air distribution and can be selected based on the specific requirements of the space.

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  • 42. 

    After you level and zero the quater-inch inclined manometer, connect its hose to the

    • Tubes

    • Pitot tube

    • Scale plate

    • Gauge stand

    Correct Answer
    A. Pitot tube
    Explanation
    The correct answer is pitot tube. The pitot tube is a device used to measure fluid flow velocity. In this context, connecting the hose of the inclined manometer to the pitot tube would allow for accurate measurement of the fluid flow velocity. The scale plate and gauge stand are not relevant to the measurement of fluid flow velocity and therefore would not be the correct options.

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  • 43. 

    To prevent needless problems to your heating, ventilation, air conditoner, and refrigeration (HVAC/R) equipment, which items should you check during V-belt inspections?

    • Outside diameter

    • Proper alignment

    • Pitch length

    • Belt alignment

    Correct Answer
    A. Proper alignment
    Explanation
    During V-belt inspections, it is important to check for proper alignment. This ensures that the V-belt is correctly positioned and aligned with the pulleys in the HVAC/R equipment. Proper alignment prevents unnecessary wear and tear on the belt, reduces friction, and ensures efficient functioning of the equipment. Checking the outside diameter, pitch length, and belt alignment are also important aspects of V-belt inspections, but the most crucial one is ensuring proper alignment.

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  • 44. 

    Which multiple-path system meets requirements of the different zones by mixing cold and warm air through dampers at the central HVAC unit?

    • High-velocity, dual-duct

    • Low-velocity, dual-duct

    • Multizone

    • Induction

    Correct Answer
    A. Multizone
    Explanation
    A multizone system is a multiple-path system that meets the requirements of different zones by mixing cold and warm air through dampers at the central HVAC unit. This system allows for individual temperature control in different areas or zones of a building, providing comfort and energy efficiency. Unlike high-velocity or low-velocity dual-duct systems, which use separate ducts for cold and warm air, a multizone system uses dampers to mix the air, making it a suitable choice for meeting the different temperature needs of various zones. Induction systems, on the other hand, use a combination of primary air and induced air to condition the space, which is not the case in this scenario.

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  • 45. 

    Which type pump casing collects water from the impeller and discharges it parallel to the

    • Multiple

    • Volute

    • Diffuser

    • Single

    Correct Answer
    A. Diffuser
    Explanation
    A pump casing collects water from the impeller and discharges it parallel to the diffuser. The diffuser is a component in a pump that helps to increase the pressure of the fluid being pumped by gradually expanding the flow area. This allows for a more efficient and smooth flow of water, reducing turbulence and increasing the overall performance of the pump. Therefore, the diffuser is the correct answer in this case.

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  • 46. 

    What is the usual pressure or medium-pressure heating when the usual design supply temperature is approximately 250*F to 350*F?

    • 140 psi

    • 150 psi

    • 160 psi

    • 180 psi

    Correct Answer
    A. 150 psi
    Explanation
    The usual pressure for medium-pressure heating is typically around 150 psi when the design supply temperature ranges from approximately 250*F to 350*F. This pressure level is considered suitable for maintaining the desired temperature range in the heating system.

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  • 47. 

    Air in HVAC work is considered and treated as

    • A mixture

    • A compound

    • An element

    • An individual gas

    Correct Answer
    A. An individual gas
    Explanation
    Air in HVAC work is considered and treated as an individual gas because it is a mixture of different gases such as nitrogen, oxygen, carbon dioxide, and others. These gases are not chemically combined but rather exist as separate entities within the air. Therefore, air is not a compound or an element, but rather a mixture of gases.

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  • 48. 

    Which piping system is a continuous run of pipe or tube from the boiler or chilled-water supply connection back to the boiler or chiller?

    • Two-pipe reverse-return

    • Two-pipe direct-return

    • Series-loop

    • One-pipe

    Correct Answer
    A. Series-loop
    Explanation
    A series-loop piping system is a continuous run of pipe or tube from the boiler or chiller back to the boiler or chiller. In this system, the water flows through the loop in a series, meaning that it passes through each terminal unit before returning to the source. This allows for equal distribution of water throughout the system and ensures balanced heating or cooling. The other options, such as two-pipe reverse-return, two-pipe direct-return, and one-pipe, do not necessarily provide a continuous run of pipe or tube back to the source.

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  • 49. 

    When a terminal unit of the hydronic distribution system is provided with two independent water coils, one served by hot water, the other by cold water, this is an example of a

    • One-pipe system

    • Two-pipe system

    • Three-pipe system

    • Four-pipe system

    Correct Answer
    A. Four-pipe system
    Explanation
    When a terminal unit of the hydronic distribution system is provided with two independent water coils, one served by hot water and the other by cold water, this is an example of a four-pipe system. In a four-pipe system, there are separate supply and return pipes for both hot and cold water, allowing for independent control and regulation of the temperature in each coil. This setup provides greater flexibility and control over the heating and cooling of the space compared to a one-pipe, two-pipe, or three-pipe system.

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Quiz Review Timeline (Updated): Mar 22, 2023 +

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

  • Current Version
  • Mar 22, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Mar 20, 2012
    Quiz Created by
    Enorab

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