CDC 3E151B : Heating, Ventilation, And Refrigeration! Hardest Trivia Quiz

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About This Quiz

Have you just finished the CDC 3E151B course on Heating, Ventilation, And Refrigeration? What is a better way there to see how attentive you are than showing off how much you learned? Take up this quiz and review what you learned. Be sure to post your score to see how you fair among others. All the best of luck!

CDC 3E151B : Heating, Ventilation, And Refrigeration! Hardest Trivia Quiz - Quiz

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  • 2. 

    To the closest tenth, what is normal atmospheric presure sea level?

    • 11 psi

    • 14.7 psi

    • 110 psi

    • 340 psi

    Correct Answer
    A. 14.7 psi
    Explanation
    Normal atmospheric pressure at sea level is approximately 14.7 psi. This is the average pressure exerted by the Earth's atmosphere on a given area at sea level. It is commonly used as a reference point for pressure measurements and is equivalent to 1 atmosphere or 101.325 kilopascals (kPa).

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  • 3. 

    What sould you do after installing a new eletrical control?

    • Give it a complete operational checkout

    • The resistance should be dropped

    • Handle control carefully

    • Replace the cover

    Correct Answer
    A. Give it a complete operational checkout
    Explanation
    After installing a new electrical control, it is important to give it a complete operational checkout. This involves testing the control to ensure that it is functioning properly and all the necessary connections have been made correctly. By conducting a thorough operational checkout, any potential issues or malfunctions can be identified and addressed before the control is put into regular use. This step is crucial in ensuring the safety and efficiency of the electrical system.

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  • 4. 

    What meter should you use to check a two-posistion control without power?

    • Ammeter

    • Voltmeter

    • Ohmmeter

    • Anemometer

    Correct Answer
    A. Ohmmeter
    Explanation
    An ohmmeter is used to measure the resistance in a circuit. In this case, since the two-position control is without power, the ohmmeter can be used to check if there is continuity or a break in the circuit. By connecting the ohmmeter to the two terminals of the control, it can determine if there is a complete path for the current to flow or if there is a break in the circuit. This can help identify any faults or issues with the control even without power.

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  • 5. 

    Perform recalibration procedures on direct digital control (DDC) systems according to the 

    • Applicable air force instruction

    • Manufacturer's instruction

    • Local building codes

    • Craftsman's discretion

    Correct Answer
    A. Manufacturer's instruction
    Explanation
    Recalibration procedures for direct digital control (DDC) systems should be performed according to the manufacturer's instructions. The manufacturer's instructions provide specific guidelines and steps for recalibrating the DDC systems, ensuring that it is done correctly and accurately. Following the manufacturer's instructions helps maintain the system's performance and functionality as intended by the manufacturer.

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  • 6. 

    What form of heat transfer most commonly used in the HVAC indusrty is

    • Conduction

    • Convection

    • Radiation

    • Radiant

    Correct Answer
    A. Convection
    Explanation
    Convection is the most commonly used form of heat transfer in the HVAC industry. Convection involves the transfer of heat through the movement of fluids, such as air or water. In HVAC systems, convection is used to distribute heated or cooled air throughout a space. This is typically achieved through the use of fans or blowers that circulate the air, allowing for efficient heating or cooling of a room or building. Convection is an important process in maintaining comfortable indoor temperatures and is widely utilized in HVAC systems.

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  • 7. 

    To begin a plotting procedure on the psychometric chart, you must know the

    • Grains of moisture and specific heat

    • Dewpoint and wet-bulb temperatures

    • Wet-bulb and dry-bulb temperatures

    • Dry-bulb and dewpoint temperatures

    Correct Answer
    A. Wet-bulb and dry-bulb temperatures
    Explanation
    To begin a plotting procedure on the psychometric chart, you must know the wet-bulb and dry-bulb temperatures. These two temperatures are essential in determining the properties of air and its moisture content. The wet-bulb temperature indicates the lowest temperature that can be achieved by evaporating water into the air, while the dry-bulb temperature represents the actual air temperature. By knowing these temperatures, one can accurately plot points on the psychometric chart to analyze and understand the thermodynamic properties of the air.

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  • 8. 

    Where isthe best place to mount the components of a pneumatic control system?

    • Close to the equipment it is controlling

    • On a steady base away from vibration

    • On the side of an air handler

    • Close to main air supply

    Correct Answer
    A. On a steady base away from vibration
    Explanation
    The best place to mount the components of a pneumatic control system is on a steady base away from vibration. This is because vibrations can interfere with the proper functioning of the system and cause inaccuracies in the control. Mounting the components on a steady base ensures stability and reduces the risk of vibrations affecting the system's performance.

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  • 9. 

    Which Air Force publication gives you electrical safety requirements?

    • AFP 91-12

    • AFI 32-1064

    • AFI 32-1999

    • AETCI 32-101

    Correct Answer
    A. AFI 32-1064
    Explanation
    AFI 32-1064 is the correct answer because it is an Air Force Instruction (AFI) that specifically addresses electrical safety requirements. This publication provides guidance and standards for electrical safety practices in the Air Force, ensuring that personnel are aware of and follow proper procedures to prevent electrical accidents and hazards.

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  • 10. 

    Single-zone systems are typically used where space conditions can be properly controlled with 

    • One sensor

    • Two sensors

    • Three sensors

    • Four sensors

    Correct Answer
    A. One sensor
    Explanation
    Single-zone systems are typically used where space conditions can be properly controlled with one sensor because a single sensor is sufficient to monitor and adjust the temperature and other environmental factors in a specific area. This is suitable for smaller spaces or rooms where the conditions remain relatively consistent throughout. Using multiple sensors would be unnecessary and potentially wasteful in terms of resources and cost.

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  • 11. 

    Conduction is the transfer of heat

    • Similar to that of light waves and radio waves

    • By the movement of a fluid such as air or water over a substance

    • Where a fan is used to propel the air across a hot or cold surface

    • Through a substance or from one body to another when the bodies are in direct contact

    Correct Answer
    A. Through a substance or from one body to another when the bodies are in direct contact
    Explanation
    Conduction is the transfer of heat through a substance or from one body to another when the bodies are in direct contact. This means that heat energy is transferred from one object to another through direct physical contact, such as when you touch a hot pan and feel the heat being conducted from the pan to your hand. Conduction is different from the transfer of heat by light waves or radio waves, as it specifically involves the movement of a fluid, like air or water, over a substance or between two objects in direct contact.

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  • 12. 

    What is the first step in cleaning up a contaminated pneumatic air supply?

    • Calibrate the instruments

    • Use a degreasing compound

    • Stop the contamination at the source

    • Retrofit the compressor air supply equipment

    Correct Answer
    A. Stop the contamination at the source
    Explanation
    The first step in cleaning up a contaminated pneumatic air supply is to stop the contamination at the source. This means identifying and addressing the cause of the contamination, such as a leak or malfunctioning equipment, and taking measures to prevent further contamination. Calibrating the instruments, using a degreasing compound, or retrofitting the compressor air supply equipment may be necessary steps in the overall cleaning process, but they should come after stopping the contamination at the source.

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  • 13. 

    What is the specific volume of one pound of dry air at standard conditions?

    • 13.33 cubic feet

    • 0.016 cubic feet

    • 29.92 inches mercury

    • 62.4 pounds/cubic foot

    Correct Answer
    A. 13.33 cubic feet
    Explanation
    The specific volume of a substance is defined as the volume occupied by a unit mass of that substance. In this question, we are asked to find the specific volume of one pound of dry air at standard conditions. The correct answer is 13.33 cubic feet, which means that one pound of dry air occupies a volume of 13.33 cubic feet. This value is derived from the properties of air and the given conditions.

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  • 14. 

    To the lowest level of supervision, who can authorize you to work on energized circuit, if mission critical?

    • Chief of operations flight

    • HVAC foreman

    • Electrical foreman

    • Base civil engineer or equivalent

    Correct Answer
    A. Base civil engineer or equivalent
    Explanation
    The base civil engineer or equivalent can authorize you to work on energized circuits at the lowest level of supervision if the task is mission critical. This means that they have the authority and knowledge to assess the risks and ensure that proper safety measures are in place before allowing work on energized circuits. The chief of operations flight, HVAC foreman, and electrical foreman may have supervisory roles, but they may not have the necessary expertise or authority to authorize such work.

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  • 15. 

    Where would you likely find the fasest moving air within a duct?

    • Along the walls

    • At the top

    • At the bottom

    • In the center

    Correct Answer
    A. In the center
    Explanation
    In a duct, the fastest moving air is likely to be found in the center. This is because air tends to follow the path of least resistance, and the center of the duct provides the least resistance to airflow. As the air moves towards the walls or the top and bottom of the duct, it encounters more friction and resistance, causing it to slow down. Therefore, the air in the center of the duct will be moving the fastest.

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  • 16. 

    What should you do after you remove the vapor degreasing compound from a pneumatic system?

    • Turn on the fans

    • Calibrate the controller

    • Change the filters in the controller

    • Flush the system with a clean air supply

    Correct Answer
    A. Flush the system with a clean air supply
    Explanation
    After removing the vapor degreasing compound from a pneumatic system, the next step should be to flush the system with a clean air supply. This is necessary to remove any remaining residue or contaminants from the system, ensuring its proper functioning. Flushing the system with clean air helps to maintain the system's efficiency and prevent any potential damage or malfunctions.

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  • 17. 

    The term for temperature control that uses no external source of energy is

    • Pneumatic

    • Electronic

    • Self-contained

    • Electromechanical

    Correct Answer
    A. Self-contained
    Explanation
    Self-contained refers to a system or device that is able to operate independently without the need for any external source of energy. In the context of temperature control, a self-contained system would be able to regulate and maintain temperature without relying on any external energy source such as electricity or pneumatic power. Therefore, self-contained is the correct term for temperature control that uses no external source of energy.

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  • 18. 

    If you are calibrating a contoller with a built-in sensor and you have adjusted the controller calibration screw to equal Pcal, your next step is to adjust the

    • Set point dial up by one-half the TRc

    • Sensitivity slides

    • Calibration screw

    • Pressure span

    Correct Answer
    A. Set point dial up by one-half the TRc
    Explanation
    After adjusting the controller calibration screw to equal Pcal, the next step is to adjust the set point dial up by one-half the TRc. This means increasing the set point by half of the TRc value. This adjustment is necessary to ensure that the controller is properly calibrated and will respond accurately to changes in the system. By adjusting the set point dial, the controller will be able to maintain the desired temperature, pressure, or any other variable being controlled.

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  • 19. 

    When calibrating a dual-input pneumatic controller, you adjust sensors oneand two to the set point value. Your next step is to adjust the

    • Action

    • Proportional band

    • Percent authority

    • Output pressure to equal calibration pressure (Pcal)

    Correct Answer
    A. Output pressure to equal calibration pressure (Pcal)
    Explanation
    After adjusting the sensors one and two to the set point value, the next step in calibrating a dual-input pneumatic controller is to adjust the output pressure to equal the calibration pressure (Pcal). This ensures that the controller is accurately responding to the input signals and producing the desired output. By adjusting the output pressure to match the calibration pressure, the controller can be fine-tuned to operate within the desired range and provide accurate control over the system.

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  • 20. 

    Sensible heat added to a substance will be indicated by a 

    • Drop in temperature of that substance

    • Change in physical state of the substance

    • Stable temperature of that substance

    • Rise in temperature of that substance

    Correct Answer
    A. Rise in temperature of that substance
    Explanation
    When sensible heat is added to a substance, it causes the temperature of the substance to increase. This is because sensible heat refers to the heat transfer that results in a change in temperature without a change in the physical state of the substance. Therefore, the correct answer is "rise in temperature of that substance."

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  • 21. 

    What would the resistance be for an electronic controller with a reference tempetature of 70*F, a reference of 100 ohms, and a rate of change of 2.2 ohms/degree that is sensing 65*F?

    • 989 ohms

    • 999 ohms

    • 1011 ohms

    • 1022 ohms

    Correct Answer
    A. 989 ohms
    Explanation
    The resistance of an electronic controller can be calculated using the formula:
    Resistance = Reference Resistance + (Rate of Change * (Sensed Temperature - Reference Temperature))
    In this case, the reference temperature is 70°F, the reference resistance is 100 ohms, the rate of change is 2.2 ohms/degree, and the sensed temperature is 65°F. Plugging these values into the formula, we get:
    Resistance = 100 + (2.2 * (65 - 70))
    Resistance = 100 + (2.2 * -5)
    Resistance = 100 - 11
    Resistance = 89 ohms
    Therefore, the correct answer is 989 ohms.

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  • 22. 

    What are the four basic methods of control in a direct digital contol (DDC) system?

    • Digital or analog outputs and digital or analog inputs

    • Digital outputs and digital or analog inputs, only

    • Digital or analog outputs and digital inputs, only

    • Digital outputs and digital inputs, only

    Correct Answer
    A. Digital or analog outputs and digital or analog inputs
    Explanation
    The four basic methods of control in a direct digital control (DDC) system are digital or analog outputs and digital or analog inputs. This means that the system can use either digital or analog outputs to control devices or equipment, and it can also receive input from either digital or analog sources to gather data or information for control purposes. This flexibility allows the DDC system to adapt to different types of devices and inputs, making it versatile and capable of controlling a wide range of systems effectively.

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  • 23. 

    The difference between a series 60 and a series 40 two-position motor is that the series 40 is

    • A line voltage circuit

    • A fail-safe control circuit

    • Used mainly where hazardous conditions exist

    • Unusable when single-pole,double throw control of line voltage is required

    Correct Answer
    A. A fail-safe control circuit
    Explanation
    The series 40 motor is described as a fail-safe control circuit. This means that it is designed to automatically shut down or switch to a safe state in the event of a failure or fault. This feature ensures that the motor will not continue to operate in a potentially dangerous or hazardous condition. In contrast, the other options do not describe the series 40 motor accurately.

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  • 24. 

    The basic purpose of the mixed-air control system is to control the amount of

    • Return air brought into the system

    • Supply air brought into the system

    • Outside air brought into the system

    • Exhaust air brought into the system

    Correct Answer
    A. Outside air brought into the system
    Explanation
    The mixed-air control system is designed to regulate the quantity of outside air that is brought into the system. This is important because outside air helps to maintain a healthy and comfortable indoor environment by diluting indoor pollutants and providing fresh oxygen. By controlling the amount of outside air, the system can ensure that the air quality is maintained at an optimal level while also conserving energy by minimizing the amount of conditioned air that needs to be supplied.

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  • 25. 

    What is the relationship among matter, energy, and heat?

    • Energy is made up of atoms, which consists of electrons kept in motion by matter, which is a form of heat

    • Heat is made up of molecules, which consists of electrons kept in motion by energy, which is a form of matter

    • Matter is made of atoms, which consists of electrons kept by heat, which is a form of energy

    • Energy is made up of molecules, which consists of electrons kept in motion by heat, which is a form of matter

    Correct Answer
    A. Matter is made of atoms, which consists of electrons kept by heat, which is a form of energy
    Explanation
    The correct answer states that matter is made of atoms, which consists of electrons kept by heat, which is a form of energy. This explanation accurately describes the relationship among matter, energy, and heat. Matter is composed of atoms, which have electrons that are kept in motion by heat. Heat is a form of energy, and it is the energy that causes the movement of electrons within atoms. Therefore, matter, energy, and heat are interconnected in this way.

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  • 26. 

    The heat that changes water at 212* F to steam at 212*F is known as

    • Latent heat of vaporization

    • Latent heat of condensation

    • Sensible heat of vaporization

    • Sensible heat of condensation

    Correct Answer
    A. Latent heat of vaporization
    Explanation
    The heat that changes water at 212* F to steam at 212* F is known as latent heat of vaporization. This is because at this temperature, the water undergoes a phase change from liquid to gas without a change in temperature. The heat energy absorbed during this process is used to break the intermolecular forces between water molecules and convert them into vapor. This latent heat of vaporization is released when the vapor condenses back into liquid form.

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  • 27. 

    When the primary variable set point of a pneumatic dual-input controller decreases as the reset variable increases, what is the reset?

    • Counter

    • Straight

    • Direct

    • Reverse

    Correct Answer
    A. Reverse
    Explanation
    In a pneumatic dual-input controller, the reset variable refers to a parameter that determines how quickly the controller responds to deviations from the set point. When the primary variable set point decreases as the reset variable increases, it indicates a reverse relationship between the two variables. This means that as the reset variable increases, the controller's response becomes slower, causing the primary variable set point to decrease. Therefore, the correct answer is "reverse."

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  • 28. 

    Which electronic controllers may combine temperature and humidity measurements to measure heat content?

    • Electric to pneumatic controllers

    • Relative humidity controllers

    • Temperature controllers

    • Enthalpy controllers

    Correct Answer
    A. Enthalpy controllers
    Explanation
    Enthalpy controllers are electronic controllers that combine temperature and humidity measurements to measure heat content. Enthalpy is a thermodynamic property that takes into account both the temperature and the amount of moisture present in the air. By combining these two measurements, enthalpy controllers provide a more accurate measurement of the heat content in a given space. This is useful in HVAC systems where precise control of temperature and humidity is required for optimal comfort and energy efficiency.

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  • 29. 

    What size energy monitoring and control system (EMCS) system has 50 to 600 points?

    • Large

    • Medium

    • Small

    • Micro

    Correct Answer
    A. Small
    Explanation
    The size of the energy monitoring and control system (EMCS) system that has 50 to 600 points is small. This implies that the system is designed to monitor and control a relatively smaller number of points or devices. It may be suitable for smaller buildings or facilities that require monitoring and control of energy usage but do not have a large number of points to manage.

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  • 30. 

    In which troubleshooting step would you identify the type of system?

    • Isolation

    • Diagnosis

    • Localization

    • Sectionalization

    Correct Answer
    A. Diagnosis
    Explanation
    In the troubleshooting process, the step of diagnosis involves identifying the type of system that is experiencing the issue. This step is crucial as it helps in understanding the specific system or component that is causing the problem. By accurately diagnosing the type of system, it becomes easier to narrow down the possible causes and find an appropriate solution.

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  • 31. 

    Saturated steam is steam

    • With more heat added

    • At a temperature below boiling water

    • At a temperature above boiling water

    • At the temperature of boiling water

    Correct Answer
    A. At the temperature of boiling water
    Explanation
    Saturated steam is steam that is at the temperature of boiling water. When water is heated to its boiling point, it starts to vaporize and form steam. Saturated steam is the point at which the water has absorbed enough heat to reach its boiling point and has completely vaporized. Therefore, it is at the same temperature as boiling water.

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  • 32. 

    When you troubleshoot a pneumatic control system, the first component you check is the 

    • Sensor

    • Controller

    • Adapter

    • Controlled device

    Correct Answer
    A. Controlled device
    Explanation
    When troubleshooting a pneumatic control system, the first component to check is the controlled device. This is because the controlled device is the final component in the system that receives the signals and performs the desired action. By checking the controlled device first, you can determine if it is functioning properly and if any issues with the system are related to its operation. Once the controlled device is confirmed to be working correctly, you can then proceed to check the other components in the system, such as the sensor, controller, and adapter, if necessary.

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  • 33. 

    When special requirements are line voltage, two-position, and "fail-safe," the type of electrical control motor you should use to operate a damper isthe series

    • 40

    • 60

    • 80

    • 90

    Correct Answer
    A. 40
    Explanation
    When special requirements include line voltage, two-position, and "fail-safe," the appropriate type of electrical control motor to use for operating a damper is the series 40.

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  • 34. 

    What basic components make-up the diret digital controls (DDC) loop?

    • Controller area network (CAN),inputs and outputs

    • Personal computer, BAC network, and DCC controller

    • Process information, input parameters, and customer needs

    • Input from a sensor or device, a building automation controller, and controlled device

    Correct Answer
    A. Input from a sensor or device, a building automation controller, and controlled device
    Explanation
    The correct answer is input from a sensor or device, a building automation controller, and controlled device. This answer accurately describes the basic components that make up the DDC loop. The input from a sensor or device provides data to the building automation controller, which then processes this information and sends commands to the controlled device for desired actions or adjustments. This loop allows for the monitoring and control of various systems in a building, such as HVAC, lighting, or security.

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  • 35. 

    In critical buildings or locations, senors for differential-pressure flow meters should be calibrated every

    • Month

    • Three months

    • Six months

    • Year

    Correct Answer
    A. Three months
    Explanation
    In critical buildings or locations, it is important to ensure that the senors for differential-pressure flow meters are accurate and reliable. Calibrating these sensors every three months helps to maintain their accuracy and detect any potential deviations or malfunctions. This regular calibration schedule allows for timely adjustments or repairs, minimizing the risk of incorrect measurements and ensuring the proper functioning of the flow meters in critical environments.

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  • 36. 

    With a multizone system, what controls the temperature to each zone?

    • The output of the hot-deck controller

    • The output of the cold deck

    • The mixed-air section

    • Zone mixing dampers

    Correct Answer
    A. Zone mixing dampers
    Explanation
    In a multizone system, the temperature to each zone is controlled by the zone mixing dampers. These dampers regulate the flow of air into each zone, allowing for individual temperature control. By adjusting the position of the dampers, the amount of heated or cooled air that enters each zone can be controlled, ensuring that each zone maintains its desired temperature. The output of the hot-deck controller, the output of the cold deck, and the mixed-air section may all play a role in the overall operation of the system, but specifically, the temperature control to each zone is achieved through the use of zone mixing dampers.

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  • 37. 

    After you have adjusted the proportinal band and percent authority on a dual-input controller, your next step is to

    • Draw performance graph

    • Find the sensor pressures

    • Disconnect both sensors and connect the simulator

    • Measure the output pressure

    Correct Answer
    A. Draw performance graph
    Explanation
    After adjusting the proportional band and percent authority on a dual-input controller, the next step is to draw a performance graph. This graph helps visualize the controller's response and performance in relation to the setpoint. By plotting the output pressure against time, any deviations or oscillations can be identified, allowing for further adjustments or troubleshooting if necessary. It is a crucial step in assessing the controller's effectiveness and ensuring optimal system performance.

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  • 38. 

    What function does spring range have in a pneumatic system?

    • The pressure range over which a high/low selector operates

    • The pressure range over which a program switch operates

    • The pressure range over which a actuator operates

    • The pressure range of a controller's internal parameters

    Correct Answer
    A. The pressure range over which a actuator operates
    Explanation
    The spring range in a pneumatic system refers to the pressure range over which an actuator operates. The actuator is a component that converts pneumatic energy into mechanical motion, and the spring range determines the range of pressures within which the actuator can function effectively. This range is important for ensuring that the actuator can perform its intended tasks within the specified pressure limits.

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  • 39. 

    You can check the voltage span of most electonic actuators by

    • Watching the system work

    • Operating the actuator from start to stop

    • Adjusting the set point dial

    • Changing the voltage output of the contoller

    Correct Answer
    A. Operating the actuator from start to stop
    Explanation
    To check the voltage span of electronic actuators, you need to operate the actuator from start to stop. By doing this, you can observe the range of voltage values that the actuator operates within. This will give you an understanding of the voltage span of the actuator and ensure that it is functioning correctly.

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  • 40. 

    How do ultrasonic flow meters measure flow?

    • By measuring a free moving element into the flow

    • By measuring the difference across the orifice plate

    • By measuring the vertical plane of a venturi tube

    • By detecting changes in sonic paths within the fluid

    Correct Answer
    A. By detecting changes in sonic paths within the fluid
    Explanation
    Ultrasonic flow meters measure flow by detecting changes in sonic paths within the fluid. This means that the flow meter uses ultrasonic waves to determine the velocity of the fluid. The meter sends out ultrasonic waves in the fluid and measures the time it takes for the waves to travel between two points. If the fluid is flowing, the waves will take longer to travel downstream compared to upstream. By analyzing the time difference, the flow rate can be calculated. This method is non-intrusive and does not require any moving parts, making it a reliable and accurate way to measure flow.

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  • 41. 

    Which test includes a sequence of operation demonstration and a control loop stability and accuracy demostration?

    • The basic field test

    • The performance verification test

    • The actuator range adjustment test

    • The application software test

    Correct Answer
    A. The performance verification test
    Explanation
    The performance verification test includes a sequence of operation demonstration and a control loop stability and accuracy demonstration. This test is designed to ensure that the system or device being tested meets the required performance standards and specifications. By conducting this test, the functionality, reliability, and accuracy of the system can be verified, providing assurance that it is capable of performing its intended tasks effectively.

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  • 42. 

    Heat content i plotted on the psychometric chart by extending the 

    • Relative humidity line

    • Dew point line

    • Dry-bulb line

    • Wet-bulb line

    Correct Answer
    A. Wet-bulb line
    Explanation
    The wet-bulb line is plotted on the psychometric chart to represent the heat content. The wet-bulb temperature is the temperature that a parcel of air would have if it were cooled to saturation by the evaporation of water into it, with the latent heat being supplied by the parcel itself. This line helps in determining the amount of heat energy present in the air at different conditions.

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  • 43. 

    Refer to figure 1-10. If the wet-bulb temperature is 57*F and the dry-bulb temperature is 65*F, what is the relative humidity?

    • 57 percent

    • 61 percent

    • 65 percent

    • 70 percent

    Correct Answer
    A. 61 percent
    Explanation
    Based on the given wet-bulb temperature of 57°F and dry-bulb temperature of 65°F, we can use a psychrometric chart to determine the relative humidity. By locating the intersection point of the wet-bulb and dry-bulb temperatures on the chart, we find that the corresponding relative humidity is approximately 61 percent.

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  • 44. 

    The two main types of switches used in electronic controls are

    • Double pole, double throw and double pole, single throw

    • Single pole, double throw and single pole, single throw

    • Snap acting and mercury switch

    • Thermostatic and mercury

    Correct Answer
    A. Snap acting and mercury switch
    Explanation
    The correct answer is snap acting and mercury switch. Snap acting switches are commonly used in electronic controls as they provide a quick and reliable response. They have a spring mechanism that allows them to rapidly switch between two positions. On the other hand, mercury switches use a small amount of mercury inside a glass tube to create a conductive path when tilted or moved. They are often used in applications where precise and stable switching is required.

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  • 45. 

    What is the advantage of timed, two-position control?

    • The final control elements moves to a position equal to the amount the controlled variable moved

    • The controller never catches up with the controlled condition

    • It greatly reduces the swings in the controlled variable

    • The thermal timer will cool

    Correct Answer
    A. It greatly reduces the swings in the controlled variable
    Explanation
    Timed, two-position control greatly reduces the swings in the controlled variable. This means that the final control element (such as a valve or damper) moves to a position equal to the amount the controlled variable moved, but it does so in a timed manner. This prevents the controller from constantly trying to catch up with the controlled condition, which can lead to overshooting and instability. By reducing swings in the controlled variable, timed, two-position control helps maintain a more stable and consistent process or system.

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  • 46. 

    To allow the passing of data to a local operator terminal or another controller, zone and system level controllers should be equipped with

    • Input/output boards

    • An analog/digital converter

    • A communications or access port

    • EEPROM

    Correct Answer
    A. A communications or access port
    Explanation
    Zone and system level controllers need to be equipped with a communications or access port in order to allow the passing of data to a local operator terminal or another controller. This port enables the controllers to send and receive information, facilitating communication and data transfer between different components of the system. The other options, such as input/output boards, analog/digital converters, and EEPROM, may have their own functions within the controllers, but they do not specifically enable communication and data transfer.

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  • 47. 

    HVAC fans noramlly provide firestats or smoke detectors and freezestats that provide for

    • Notification of emergency personnel

    • Control fire, smoke, and freezing

    • Fire and freeze suppression

    • Emergency fan shutdown

    Correct Answer
    A. Emergency fan shutdown
    Explanation
    The correct answer is "emergency fan shutdown". HVAC fans typically have firestats or smoke detectors and freezestats that are designed to detect emergencies such as fires, smoke, or freezing temperatures. When these emergency situations are detected, the HVAC system will automatically shut down the fans to prevent further spread of fire or smoke, or to protect the system from damage due to freezing conditions. This shutdown helps to control and mitigate the emergency situation.

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  • 48. 

    What is used in a humidity control subsytem to keep the humidity in the ductwork from getting to high?

    • Airflow switch

    • Normally closed humidifier

    • Low-limit humidity controller

    • High-limit humidity controller

    Correct Answer
    A. High-limit humidity controller
    Explanation
    A high-limit humidity controller is used in a humidity control system to prevent the humidity in the ductwork from reaching excessively high levels. It is designed to monitor the humidity levels and activate when the humidity exceeds a predetermined high limit. Once activated, it triggers the system to take corrective measures such as reducing the amount of moisture being added to the air or increasing the airflow to lower the humidity. This helps maintain a comfortable and balanced humidity level in the ductwork, preventing any potential damage or discomfort caused by excessive humidity.

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  • 49. 

    Which sensor is used to measure temperature changes caused by stratification?

    • Ceiling diffuser

    • Averaging bulb

    • Insertion sensor

    • Humidity sensor

    Correct Answer
    A. Averaging bulb
    Explanation
    An averaging bulb is used to measure temperature changes caused by stratification. Stratification refers to the layering of different temperatures within a space, typically due to variations in air density. An averaging bulb is designed to capture an average temperature reading by drawing air from multiple points within the space, thus providing a more accurate representation of the overall temperature profile. This makes it an ideal sensor for measuring temperature changes caused by stratification.

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Quiz Review Timeline (Updated): Mar 20, 2023 +

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

  • Current Version
  • Mar 20, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Mar 08, 2012
    Quiz Created by
    Enorab
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