CDC 3E151P: Trivia Quiz On Heating, Ventilation And Refrigeration!

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1. Refrigerants containing chlorine are said to destroy

Explanation

Refrigerants containing chlorine are said to destroy ozone because chlorine atoms can react with ozone molecules in the stratosphere. This reaction results in the breakdown of ozone, leading to the depletion of the ozone layer. This is a significant environmental concern as the ozone layer plays a crucial role in protecting the Earth from harmful ultraviolet (UV) radiation. The destruction of ozone can lead to increased UV radiation reaching the Earth's surface, which can have detrimental effects on human health and ecosystems.

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About This Quiz
CDC 3E151P: Trivia Quiz On Heating, Ventilation And Refrigeration! - Quiz

Welcome to the CDC 3e151p trivia Quiz on heating, ventilation, and Refrigeration. This course teaches you how to store food and maintain heat in different situations, considering one would not know where they are posted or would end up. Take it up and get to see what your chances of... see moresurvival are even batting camp. All the best in the exams! see less

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2. The best critera to follow when you are inspecting equipment are

Explanation

When inspecting equipment, it is best to follow the manufacturer's recommendations. This is because the manufacturer knows the equipment best and can provide specific instructions on how to properly inspect and maintain it. Following these recommendations ensures that the equipment is inspected correctly, minimizing the risk of damage or malfunction. Additionally, adhering to the manufacturer's recommendations may be necessary to maintain any warranties or guarantees on the equipment.

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3. You are retrofitting a system that does not have a receiver. To do the job properly, you would store the refrigerant in

Explanation

When retrofitting a system that does not have a receiver, it is important to store the refrigerant in a recovery cylinder. This is because a recovery cylinder is designed specifically for storing refrigerants safely and securely. It allows for proper containment and disposal of the refrigerant during the retrofitting process. Storing the refrigerant in the compressor, condenser, or evaporator would not be appropriate or safe in this situation.

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4. Complete vaporization in an evaporator occurs at point

Explanation

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5. What must you do to the power before you perform a preoperational check on a HVAC/R system?

Explanation

Before performing a preoperational check on a HVAC/R system, it is necessary to turn off the power and confirm it with a meter. This ensures the safety of the person performing the check as well as prevents any damage to the system. By turning off the power, the risk of electric shock or injury is minimized. Confirming with a meter helps to ensure that the power is indeed turned off and there is no residual electrical current flowing through the system.

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6. Which major component is considered to be the "heart" of the refrigeration system?

Explanation

The compressor is considered to be the "heart" of the refrigeration system because it plays a crucial role in the refrigeration cycle. It is responsible for compressing the refrigerant gas, which increases its temperature and pressure. This high-pressure gas then flows to the condenser where it releases heat and condenses into a high-pressure liquid. The compressor also helps to circulate the refrigerant throughout the system, ensuring efficient cooling. Without the compressor, the refrigeration system would not be able to function properly.

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7. Two different metals that are bonded into a strip or coil are called

Explanation

Bimetal refers to two different metals that are bonded into a strip or coil. This term is commonly used in the field of engineering and construction, where the combination of two metals with different properties can provide unique advantages. The bonding of these metals allows for the creation of materials that have enhanced strength, durability, and resistance to corrosion or temperature changes. Bimetal is a widely used term in various industries, including automotive, aerospace, and electrical.

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8. The advantage of an air-cooled condenser is

Explanation

An air-cooled condenser has the advantage of requiring less maintenance compared to other types of condensers. This is because it does not use water or other fluids for cooling, eliminating the need for regular maintenance and potential issues such as leaks or corrosion. The absence of fluid also reduces the risk of contamination and the need for monitoring and treating the fluid. Overall, this results in lower maintenance costs and less time spent on upkeep, making air-cooled condensers a more convenient and cost-effective option.

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9. Which evaporator operating condition uses air circulation to aid in defrosting?

Explanation

Defrosting is the correct answer because it involves the use of air circulation to aid in removing frost or ice buildup on the evaporator. This process helps to melt the frost or ice faster and more efficiently, allowing the evaporator to resume its normal cooling function.

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10. All moving parts on an air compressor should have

Explanation

Guards should be installed on all moving parts of an air compressor to ensure safety. These guards serve as protective barriers that prevent accidental contact with the moving parts, reducing the risk of injury. By having guards in place, any potential hazards or accidents that could occur from coming into contact with the moving parts are minimized. Therefore, it is essential to have guards installed on all moving parts of an air compressor.

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11. Where are the coldest rooms located in a permanent cold-storage plant?

Explanation

The coldest rooms in a permanent cold-storage plant are located inside the plant. This is because the purpose of a cold-storage plant is to maintain low temperatures for the storage of perishable items. By keeping the coldest rooms inside the plant, it allows for better insulation and control of temperature, ensuring that the desired cold conditions are maintained.

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12. What program is designed to keep HVAC/R equipment in operational condition?

Explanation

A recurring maintenance program is designed to keep HVAC/R equipment in operational condition. This program involves regularly scheduled inspections, cleaning, and servicing of the equipment to ensure its optimal performance and prevent any potential breakdowns or malfunctions. By implementing a recurring maintenance program, HVAC/R equipment can be kept in good working order, prolonging its lifespan and reducing the likelihood of costly repairs or replacements.

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13. The disadvantage of water-cooled condensers is

Explanation

Water-cooled condensers have the disadvantage of higher cost compared to other types of condensers. This is because water-cooled condensers require additional equipment such as water pumps, cooling towers, and water treatment systems, which can increase the overall cost of the system. Additionally, the installation and maintenance of water-cooled condensers can also be more expensive compared to other types of condensers. Therefore, the higher cost is a drawback of water-cooled condensers.

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14. A good refrigerant oil will have

Explanation

A good refrigerant oil should have low viscosity because it needs to flow easily through the refrigeration system to ensure efficient heat transfer and lubrication. If the oil has high viscosity, it may cause resistance to flow, leading to reduced cooling capacity and increased energy consumption. Additionally, low viscosity helps the oil to circulate effectively and reach all the necessary components in the system, ensuring proper lubrication and preventing wear and tear. Therefore, low viscosity is an important characteristic for a good refrigerant oil.

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15. The direct-expansion evaporator picks up or absorbs heat directly from the

Explanation

The direct-expansion evaporator is responsible for picking up or absorbing heat directly from the conditioned space. This means that it extracts heat from the air in the area being cooled and transfers it to the refrigerant. This process allows the evaporator to cool down the conditioned space by removing the heat from it.

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16. What term refers to how hot or cold a substance is?

Explanation

Temperature refers to how hot or cold a substance is. It is a measure of the average kinetic energy of the particles in a substance. When the particles have higher kinetic energy, the substance is hotter, and when the particles have lower kinetic energy, the substance is colder. Temperature is measured using various scales such as Celsius, Fahrenheit, and Kelvin. It is an important property in thermodynamics and plays a crucial role in determining the behavior and properties of substances.

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17. Which refrigerant oil is designed for use with the new ternary blend refrigerants?

Explanation

Alkyl benzene oil is designed for use with the new ternary blend refrigerants. This type of refrigerant oil is compatible with these specific blend refrigerants and is formulated to provide optimal performance and efficiency in refrigeration systems that use them.

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18. Cleaning a refrigerant at the job site or at a local service shop is called

Explanation

The process of cleaning a refrigerant either at the job site or at a local service shop is referred to as recycling. This involves removing any impurities or contaminants from the refrigerant so that it can be reused. Recycling helps to minimize waste and promotes the sustainable use of resources. Reclamation refers to the process of restoring a refrigerant to its original state, while redeeming and recovery are not relevant to the context of cleaning a refrigerant.

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19. Which heat pump component prevents liquid refrigerant from entering the compressor?

Explanation

The accumulator is the heat pump component that prevents liquid refrigerant from entering the compressor. It is located between the evaporator and the compressor and acts as a storage tank for any liquid refrigerant that may have escaped from the evaporator. The accumulator allows the refrigerant to vaporize before entering the compressor, preventing any potential damage that could be caused by liquid refrigerant entering the compressor.

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20. How does the rotary compressor compress the refrigerated vapor?

Explanation

The rotary compressor compresses the refrigerated vapor through a squeezing action. As the rotary blades rotate, they create a tight seal with the compressor housing, trapping the vapor inside. As the blades continue to rotate, the vapor is squeezed and compressed, resulting in an increase in pressure. This squeezing action allows the compressor to effectively compress the vapor and move it through the refrigeration system.

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21. What type of rotary compressor has the blade set into the cylinder?

Explanation

A rotary compressor with a stationary blade has the blade set into the cylinder. This means that the blade is fixed in position and does not move during operation. This type of compressor design allows for efficient compression of gases or fluids as they pass through the cylinder. The stationary blade creates a seal that helps to prevent leakage and ensures that the compression process is effective.

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22. An ice-cream cabinet is similar to a

Explanation

An ice-cream cabinet is similar to a chest-type freezer because both have a similar design and purpose. A chest-type freezer typically has a top-opening door and a deep storage space, allowing for efficient storage and organization of frozen items. Similarly, an ice-cream cabinet is designed to store and display ice cream products, usually with a top-opening door and ample space for storing multiple flavors. Both the chest-type freezer and ice-cream cabinet are commonly used in commercial settings such as grocery stores or ice cream parlors to keep frozen items at the desired temperature.

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23. Which of these refrigerants has an ozone depletion rating of zero?

Explanation

R-134a is the correct answer because it has an ozone depletion rating of zero. This means that it does not contribute to the depletion of the ozone layer. R-12 and R-22, on the other hand, have ozone depletion potentials and can contribute to ozone depletion. R-500 is a blend of refrigerants and does not have a zero ozone depletion rating.

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24. How much of the refrigerant charge should a receiver hold?

Explanation

The receiver in a refrigeration system is designed to hold the entire amount of refrigerant charge. It acts as a storage tank for the refrigerant, ensuring that there is a sufficient amount available for the system to operate efficiently. By holding the entire charge, the receiver helps to maintain the proper amount of refrigerant in the system and prevent any fluctuations or shortages that could affect its performance.

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25. What device is used to prevent liquid refrigerant from entering the compressor?

Explanation

The accumulator is a device used to prevent liquid refrigerant from entering the compressor. It is located between the evaporator and the compressor in a refrigeration system. Its purpose is to collect any liquid refrigerant that may have not evaporated in the evaporator and prevent it from reaching the compressor. This is important because liquid refrigerant entering the compressor can cause damage to the compressor and affect the overall performance of the system.

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26. Which packaged unit normally uses only one fan motor?

Explanation

A window unit is a type of packaged unit that typically uses only one fan motor. This type of unit is designed to be installed in a window or a hole in a wall, and it contains all the necessary components for cooling or heating a single room. The single fan motor is responsible for both the circulation of air within the unit and the expulsion of hot air to the outside. This design allows for a compact and efficient cooling or heating solution for small spaces.

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27. What is a big problem with humidity control equipment?

Explanation

Scale is a big problem with humidity control equipment. Scale refers to the buildup of mineral deposits, such as calcium and magnesium, on the surfaces of the equipment. This can occur when water with high mineral content is used in the equipment. Scale can reduce the efficiency of the equipment, restrict water flow, and potentially cause damage to the equipment over time. Regular maintenance and cleaning are necessary to prevent and remove scale buildup in humidity control equipment.

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28. Which processes take place inside the condenser?

Explanation

Inside the condenser, two processes take place: desuperheating and condensing. Desuperheating refers to the process of removing excess heat from the superheated vapor, reducing its temperature to the saturation point. Condensing, on the other hand, involves the transformation of the vapor into a liquid state by removing heat, resulting in the release of latent heat. These processes are essential in the condenser as they help in the transfer of heat from the vapor to the cooling medium, allowing the vapor to be converted back into a liquid state.

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29. Which component is installed at the inlet of the evaporator?

Explanation

The metering device is installed at the inlet of the evaporator. This component is responsible for regulating the flow of refrigerant into the evaporator, ensuring that the correct amount of refrigerant enters the evaporator coil. It controls the pressure and flow rate of the refrigerant, allowing it to expand and cool down as it passes through the evaporator. By controlling the flow of refrigerant, the metering device helps to maintain the desired temperature and pressure levels within the evaporator, ensuring efficient and effective cooling.

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30. To create the required pressure drop, the capillary tube uses a designed

Explanation

The capillary tube uses resistance to create the required pressure drop. Resistance refers to the obstruction or hindrance to the flow of fluid through a tube or pipe. In this case, the capillary tube is designed in a way that it offers a certain level of resistance to the flow of fluid, causing a pressure drop. This pressure drop is necessary for various applications such as controlling the flow rate or regulating the pressure within a system.

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31. When the compressor air intake is piped to the outside, it should be

Explanation

The compressor air intake should be six feet above the ground when it is piped to the outside. This height ensures that the intake is not obstructed by any potential obstructions on the ground, such as debris or water. By placing the intake higher, the compressor can draw in cleaner and dryer air, which helps to maintain the efficiency and longevity of the equipment.

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32. The float assembly in an oil separator is activated by the

Explanation

The float assembly in an oil separator is activated by the level of the oil. This means that as the oil level rises, the float assembly will be triggered and activate a mechanism to separate the oil from other substances. The level of the oil is an important factor in determining when and how the oil separator should be activated, as it ensures that the separation process occurs at the appropriate time.

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33. Which refrigeration compressor is equipped with pistons and connecting rods?

Explanation

A reciprocating refrigeration compressor is equipped with pistons and connecting rods. This type of compressor uses a piston-cylinder arrangement to compress the refrigerant gas. The piston moves back and forth in the cylinder, creating a suction stroke to draw in the refrigerant and a compression stroke to compress the refrigerant. The connecting rod connects the piston to the crankshaft, allowing the reciprocating motion. This type of compressor is commonly used in small to medium-sized refrigeration systems.

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34. You are retrofitting a system with an alternative refrigerant and you determine that the capillary tube must be replaced. To do the job correctly, you would replace the capillary tube with one having

Explanation

To retrofit a system with an alternative refrigerant, replacing the capillary tube with one having greater resistance and longer length is the correct approach. This is because the alternative refrigerant may have different flow characteristics compared to the original refrigerant. By increasing the resistance and length of the capillary tube, it helps to regulate and control the flow of the refrigerant, ensuring proper cooling and system performance.

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35. What must be balanced to distribute the load as equally as possible between multiple compressors?

Explanation

To distribute the load as equally as possible between multiple compressors, the refrigerant lines must be balanced. Refrigerant lines carry the refrigerant from the evaporator to the condenser and back, and if they are not balanced, it can result in uneven distribution of the workload among the compressors. Balancing the refrigerant lines ensures that each compressor receives an equal amount of refrigerant, leading to more efficient and effective operation of the system.

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36. What triggers a refrigeration unit to cycle on or off?

Explanation

A refrigeration unit cycles on or off based on the control circuit. The control circuit is responsible for monitoring the temperature and activating the compressor when the temperature rises above a certain threshold. It also turns off the compressor when the temperature reaches the desired level. Therefore, the control circuit is the component that triggers the refrigeration unit to cycle on or off.

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37. What is the term for a refrigeration unit to operate or cycle on?

Explanation

The term for a refrigeration unit to operate or cycle on is "cut-in." This refers to the temperature at which the unit starts running to cool the space. Once the temperature rises above the cut-in point, the refrigeration unit turns on and begins the cooling cycle.

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38. The Environmental Protection Agency (EPA) has developed a Significant New Alternatives Policy (SNAP) Program. This program is used to determine

Explanation

The SNAP Program developed by the EPA is used to determine the risks that alternative refrigerants pose to human health and the environment. This suggests that the program focuses on evaluating the potential negative effects of using alternative refrigerants on both human health and the environment. The program likely assesses the potential for these refrigerants to contribute to air pollution, ozone depletion, or climate change, and considers the potential health risks associated with their use.

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39. Which organization requires that a comprehensive risk assessment be performed to estimate the likelihood of fire and potential results should a fire occur when alternative refrigerants contain a flammable component?

Explanation

The correct answer is the Environmental Protection Agency (EPA). The EPA requires a comprehensive risk assessment to be performed to estimate the likelihood of fire and potential results should a fire occur when alternative refrigerants contain a flammable component. This is likely because the EPA is responsible for regulating and protecting the environment, including the safety and potential hazards associated with refrigerants.

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40. Which compressor type is used with refrigerants that have a large gas volume?

Explanation

Centrifugal compressors are used with refrigerants that have a large gas volume because they are capable of handling high flow rates and can efficiently compress large volumes of gas. These compressors use centrifugal force to accelerate the refrigerant gas and then convert the kinetic energy into pressure energy. This makes them suitable for applications where a large volume of gas needs to be compressed, such as in large-scale industrial refrigeration systems or air conditioning units.

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41. On a centrifugal machine, the refrigerant flows from the first-stage impeller to the

Explanation

In a centrifugal machine, the refrigerant flows from the first-stage impeller to the second-stage impeller. The purpose of the impellers is to increase the pressure and velocity of the refrigerant, which allows it to move through the system. The second-stage impeller further increases the pressure and velocity of the refrigerant before it moves on to the next component in the system. This is an important step in the refrigeration process as it helps to maintain the efficiency and effectiveness of the system.

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42. What is the maximum fine and jail sentence that service technicians may be subject to for charging a system with an unacceptable refrigerant?

Explanation

Service technicians may be subject to a maximum fine of $25,000 and a jail sentence of up to 5 years for charging a system with an unacceptable refrigerant.

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43. What prevents direct impact of refrigerant vapors on the tubing bundle of the centrifugal system condenser?

Explanation

The baffle plate prevents direct impact of refrigerant vapors on the tubing bundle of the centrifugal system condenser. It acts as a barrier or shield, redirecting the flow of the vapors and preventing them from directly hitting the tubing bundle. This helps to protect the tubing from any potential damage or corrosion that could be caused by the impact of the vapors.

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44. In a multistage air-compressor installation, what is used to remove heat between the stages?

Explanation

Intercoolers are used to remove heat between the stages in a multistage air-compressor installation. As the air is compressed in each stage, its temperature increases. Intercoolers are placed between the stages to cool down the compressed air before it enters the next stage, preventing overheating and improving the efficiency of the compressor. By removing the heat, intercoolers help to reduce the workload on subsequent stages and increase the overall performance of the air-compressor installation.

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45. The receiver thanks used on air compressor are designed to be

Explanation

The receiver tanks used on air compressors are designed to be air storage tanks. These tanks store compressed air that can be used later when needed. Compressed air is stored in these tanks to ensure a steady and consistent supply of air, especially during peak usage periods. This helps to maintain the efficiency and effectiveness of the air compressor system.

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46. To help ensure that the proper refrigerant and lubricant will be used in a system in the future, you would

Explanation

Labeling the components and system would help ensure that the proper refrigerant and lubricant will be used in the future. By clearly identifying the components and system, technicians will be able to easily identify the correct refrigerant and lubricant to use, preventing any potential mistakes or errors. This labeling system would provide clear and accurate information for future maintenance and servicing of the system.

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47. Which desiccant is the most popular and can be left in the system indefinitely?

Explanation

Silica gel is the most popular desiccant that can be left in the system indefinitely. It is commonly used because it has a high adsorption capacity, meaning it can absorb and hold a large amount of moisture. It is also non-toxic and non-reactive, making it safe to use in various applications. Silica gel is often used in packaging to prevent moisture damage to products, and it can be easily regenerated by heating, allowing for its long-term use.

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48. Temperature glide in an zeotropic refrigerant means that the refrigerant is a

Explanation

Temperature glide in a zeotropic refrigerant refers to the phenomenon where the refrigerant blend evaporates and condenses over a range of temperatures instead of a single temperature. This means that different components of the blend have different boiling and condensing points, causing the blend to behave as a mixture rather than a single substance. As a result, the refrigerant's properties change gradually as it goes through the evaporation and condensation processes, leading to a temperature glide.

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49. On Type II systems, what level of evacuation in the isolated component must be attained when you are making minor repairs of items such as a filter-drier or a strainer?

Explanation

When making minor repairs on Type II systems, such as replacing a filter-drier or a strainer, the level of evacuation required in the isolated component is 0 pounds per square inch gauge (psig). This means that the component should be completely free of any pressure. This is necessary to ensure that no air or moisture is present in the system, which could negatively affect its performance and efficiency. By achieving a vacuum level of 0 psig, any potential contaminants can be effectively removed, allowing for proper functioning of the system after the repairs are made.

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50. When conducting an operational check of the mechanical part of a HVAC/R system, you should check

Explanation

When conducting an operational check of the mechanical part of a HVAC/R system, it is important to check the system pressures. This is because system pressures can indicate if the system is functioning properly and if there are any issues such as leaks or blockages. By checking the system pressures, technicians can ensure that the HVAC/R system is operating at the correct levels and identify any potential problems that may need to be addressed. Checking system pressures is an essential part of maintaining and troubleshooting HVAC/R systems.

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51. Commercial and industrial systems with leaks exceeding what percent per year will require repair?

Explanation

Commercial and industrial systems with leaks exceeding 35% per year will require repair. This means that if the leaks in these systems exceed 35% of the total volume per year, they will need to be fixed. A leak exceeding this percentage indicates a significant problem that needs to be addressed in order to ensure the proper functioning and efficiency of the systems.

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52. Heat that is picked up in the refrigeration system is rejected at the

Explanation

The heat that is picked up in the refrigeration system is rejected at the condenser. The condenser is responsible for transferring heat from the refrigerant to the surrounding environment, causing the refrigerant to condense back into a liquid state. This process releases the heat that was absorbed from the cooled space, allowing the refrigerant to be ready for another cycle of cooling.

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53. R–401A is not a suitable alternative refrigerant for

Explanation

R-401A is not a suitable alternative refrigerant for residential air conditioners because it is not compatible with the specific requirements and operating conditions of these cooling systems. It may not provide optimal cooling performance or efficiency, and could potentially cause damage or malfunction in the residential air conditioning units. Therefore, it is important to use a refrigerant that is specifically designed and recommended for residential air conditioners to ensure proper functioning and longevity of the equipment.

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54. What type of heat when added to a substance causes a measured temperature change without a change of state?

Explanation

Sensible heat refers to the heat that causes a measurable change in temperature without causing a change in the state of the substance. This means that the substance remains in the same physical state (solid, liquid, or gas) while its temperature increases or decreases. Sensible heat can be measured using a thermometer and is commonly used in everyday applications such as heating or cooling systems.

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55. How is the capillary tube in a system affected by the refrigerant charge?

Explanation

The capillary tube in a system is affected by the refrigerant charge because the refrigerant charge refers to the amount of refrigerant present in the system. If the refrigerant charge is not at the correct level, it can cause issues with the operation of the capillary tube. If there is too much refrigerant, it can lead to excessive pressure and potentially damage the capillary tube. On the other hand, if there is too little refrigerant, it can result in insufficient cooling and reduced efficiency of the capillary tube. Therefore, the refrigerant charge being critical means that it needs to be at the correct level for the capillary tube to function properly.

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56. Where do you install a sight glass and/or moisture indicator in a refrigeration system?

Explanation

A sight glass and/or moisture indicator is installed in the liquid line of a refrigeration system. This allows for easy visual inspection of the refrigerant flow and the presence of any moisture in the system. Installing it in the liquid line ensures that it is located after the condenser and receiver, where the refrigerant has been condensed and any moisture should have been removed. This placement allows for accurate monitoring of the refrigerant condition and helps prevent potential issues caused by moisture contamination.

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57. What do filter-driers not remove from a refrigeration system?

Explanation

Filter-driers are components in a refrigeration system that are designed to remove contaminants such as acids, sludge, and moisture. However, they are not effective in removing sand particles. Sand can cause damage to the system by clogging valves, blocking refrigerant flow, and causing mechanical wear on components. Therefore, it is important to have additional filters or screens in place to prevent sand from entering the system.

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58. Which type piston can suction gas pass through?

Explanation

A trunk piston is designed with a hollow space in the center called a trunk, which allows gas to pass through. This type of piston is commonly used in internal combustion engines where the fuel-air mixture is drawn into the combustion chamber through the trunk. The other options, such as plug, plate, and forged pistons, do not have this feature and therefore do not allow gas to pass through.

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59. In which major component does absorbed heat cause liquid refrigerant to boil?

Explanation

When absorbed heat is applied to the liquid refrigerant, it causes the refrigerant to boil. This process occurs in the evaporator, which is a major component of a refrigeration system. The evaporator is responsible for absorbing heat from the surrounding environment, such as the air in a room or the contents of a refrigerator. As the absorbed heat is transferred to the refrigerant, it causes the liquid refrigerant to evaporate and turn into a gas. This gas then travels to the compressor, where it is pressurized and further heated before entering the condenser.

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60. The purge unit on a centrifugal machine is not designed to

Explanation

The purge unit on a centrifugal machine is designed to remove contaminants from the system, including contaminated oil. It is not designed to remove air, water, or recover refrigerant. The purpose of the purge unit is to ensure that the system operates efficiently by removing any impurities that may affect its performance.

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61. When polyolester oil is used in place of mineral oil during a retrofit procedure, you must make sure that less than what percent of mineral oil can remain in the system?

Explanation

During a retrofit procedure, when polyolester oil is used instead of mineral oil, it is important to ensure that less than 5% of mineral oil remains in the system. This is because the two types of oil are not compatible and can cause issues if they mix. Therefore, it is necessary to thoroughly flush the system and remove as much mineral oil as possible to avoid any potential problems.

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62. Air intake filters used on air compressors are designed to prevent

Explanation

The air intake filters used on air compressors are designed to prevent unnecessary wear. These filters are responsible for trapping dust, debris, and other contaminants present in the air, preventing them from entering the compressor's internal components. By filtering out these particles, the filters help to maintain clean and smooth operation of the compressor, reducing the risk of wear and tear on its parts. This ultimately extends the lifespan of the compressor and ensures optimal performance.

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63. Which of these refrigerants is colorless and has a very pronounced odor?

Explanation

R-717, also known as ammonia, is a colorless refrigerant with a very pronounced odor. Ammonia is commonly used in industrial refrigeration systems due to its excellent thermodynamic properties. However, its strong smell makes it easily detectable in case of leaks, which is an important safety feature.

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64. During retrofitting, which component might have to be reset to compensate for higher discharge pressures?

Explanation

During retrofitting, when higher discharge pressures are experienced, the high-pressure cutout component may need to be reset. This is because the high-pressure cutout is designed to protect the system from excessive pressure. By resetting it, the cutout can be adjusted to a higher pressure threshold, allowing it to accommodate the increased discharge pressures that occur during retrofitting.

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65. Which cooler is used exclusively to cool liquids?

Explanation

The Baudelot cooler is used exclusively to cool liquids. It is a type of heat exchanger that consists of a bundle of tubes through which the liquid flows, while the cooling medium, usually water, circulates around the tubes. This design allows for efficient heat transfer between the liquid and the cooling medium, effectively cooling the liquid. The other options, tank-type, shell-and-coil, and shell-and-tube, may be used for various cooling applications but are not exclusively designed for cooling liquids.

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66. The ultralow-temperature classification begins at

Explanation

The ultralow-temperature classification begins at -20*F because this temperature is significantly lower than the other options listed. Ultralow temperatures are defined as extremely cold temperatures that are well below freezing. While 0*F, -5*F, and -10*F are all cold temperatures, they do not meet the criteria for ultralow temperatures. However, -20*F falls well below freezing and is considered to be an ultralow temperature.

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67. In relation to the curve, where is the liquid refrigerant shown on the pressure-enthalpy (PE) chart?

Explanation

The liquid refrigerant is shown on the left side of the pressure-enthalpy (PE) chart. This indicates that the refrigerant is in a liquid state and has a lower pressure and enthalpy compared to other points on the chart. The left side of the chart typically represents the region where the refrigerant is in a condensed state, before it undergoes any phase change.

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68. Which evaporator type is designed to maintain an even temperature throughout the refrigerated space?

Explanation

Forced-convection evaporators are designed to maintain an even temperature throughout the refrigerated space. This type of evaporator uses a fan or blower to circulate air over the evaporator coil, ensuring that the cold air is evenly distributed throughout the space. This helps to prevent hot spots or cold spots in the refrigerated area, providing consistent cooling and maintaining a uniform temperature. Bare-tube and finned-tube evaporators do not have the same level of air circulation, while natural-convection evaporators rely on the natural movement of air, which may not be as effective in maintaining an even temperature.

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69. Proportionately which refrigerator has the biggest freezer compartment?

Explanation

The side-by-side refrigerator has the biggest freezer compartment compared to the other options. This type of refrigerator has the freezer compartment located on one side and the refrigerator compartment on the other side, with both compartments having equal vertical space. This design allows for a larger freezer compartment, making it the best option for those who require more freezer storage.

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70. The connecting point of a cascade system is

Explanation

The connecting point of a cascade system is a condenser-evaporator. In a cascade system, two separate refrigeration cycles are used, with one cycle operating at a lower temperature than the other. The condenser-evaporator acts as a heat exchanger, transferring heat from the low-temperature cycle to the high-temperature cycle. This allows for efficient cooling at very low temperatures, making cascade systems ideal for applications such as ultra-low temperature freezers and cryogenic systems.

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71. Which type of compressor uses an orbiting motion for compression?

Explanation

A scroll compressor uses an orbiting motion for compression. In a scroll compressor, two spiral-shaped scrolls are used, one fixed and one orbiting. The orbiting scroll moves in a circular motion, creating a series of gas pockets that gradually decrease in size, compressing the gas. This design allows for smooth and efficient compression without the need for valves or pistons, making scroll compressors popular for applications requiring quiet operation and high efficiency.

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72. R–401A and B can be described as a/an

Explanation

R-401A and B are described as hydrofluorocarbon (HFC)-based alternatives. This means that they are alternatives that use HFCs as their main components. HFCs are a type of synthetic refrigerant that do not contain chlorine, making them less harmful to the ozone layer compared to chlorofluorocarbons (CFCs). HFC-based alternatives are commonly used in refrigeration and air conditioning systems as a more environmentally friendly option.

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73. Which type of water-cooled condenser has removable heads that allow the tubes to be cleaned out with a revolving brush?

Explanation

A shell-and-tube water-cooled condenser has removable heads that allow the tubes to be cleaned out with a revolving brush. This design allows for easy maintenance and cleaning of the condenser tubes, ensuring efficient heat transfer and preventing any blockages or build-up of debris. The removable heads provide access to the tubes, allowing for thorough cleaning and maintenance to keep the condenser operating effectively.

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74. How many air-compressor starts per hour would require a constant control?

Explanation

An air-compressor that requires constant control would mean that it needs to be started and stopped frequently throughout the hour. The higher the number of starts per hour, the more frequently the compressor would need to be controlled. Therefore, out of the given options, 13 air-compressor starts per hour would require constant control.

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75. The economizer on a centrifugal machine prevents liquid refrigerant from enetering the compressor through the use of

Explanation

Eliminator baffles are used in the economizer of a centrifugal machine to prevent liquid refrigerant from entering the compressor. These baffles help separate the liquid refrigerant from the vapor refrigerant, allowing only the vapor to enter the compressor. By preventing liquid refrigerant from entering the compressor, the eliminator baffles help maintain the efficiency and performance of the centrifugal machine.

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76. What is it called when two or more compressors are piped in series to one another?

Explanation

When two or more compressors are piped in series to one another, it is called compounding. This means that the output of one compressor is fed into the input of the next compressor, resulting in a cumulative increase in pressure. This method is often used to achieve higher levels of compression in industrial processes or applications where a single compressor may not be sufficient.

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77. During equipment cooling, humidity cannot be added to the air by

Explanation

Saturating the coils with warm water cannot add humidity to the air during equipment cooling because the warm water will not evaporate into the air. In order to add humidity to the air, water needs to evaporate, and this cannot happen if the coils are already saturated with warm water.

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78. In which two parts of a refrigeration system does a pressure change take place?

Explanation

In a refrigeration system, a pressure change takes place in the compressor and metering device. The compressor is responsible for increasing the pressure of the refrigerant gas, while the metering device is responsible for reducing the pressure of the refrigerant as it enters the evaporator. This pressure change is essential for the refrigeration cycle to work effectively, as it allows the refrigerant to absorb heat in the evaporator and release it in the condenser.

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79. Which alternative replacement for R–502 is a patented azeotrope?

Explanation

R-507 is a patented azeotrope that can be used as an alternative replacement for R-502. Azeotropes are mixtures of two or more substances that behave like a single substance, meaning they have a constant boiling point and composition. R-507 is a blend of hydrofluorocarbons (HFCs) that has been specifically formulated to mimic the properties of R-502, making it a suitable replacement for this refrigerant.

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80. Which pressure control has contacts that open on a rise in pressure?

Explanation

A high-pressure safety switch is designed to open its contacts when the pressure rises above a certain threshold. This is done to prevent damage or unsafe conditions that may occur at high pressures. Therefore, the contacts of a high-pressure safety switch open on a rise in pressure.

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81. What type maintenance action do you perform on operating HVAC/R systems?

Explanation

Performing an operational check on operating HVAC/R systems involves testing and verifying the functionality and performance of the system. This includes checking the temperature, pressure, airflow, and other parameters to ensure that the system is operating correctly. It helps identify any issues or malfunctions that may be affecting the system's performance and allows for timely repairs or adjustments to be made. Performing an operational check is an essential maintenance action to ensure the efficient and reliable operation of HVAC/R systems.

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82. Which type of ice-machine evaporator produces a slab of ice that is moved onto a hot wire grid?

Explanation

A horizontal plate ice-machine evaporator produces a slab of ice that is moved onto a hot wire grid. The horizontal plate evaporator consists of a flat, horizontal surface that is cooled by a refrigerant. Water is sprayed onto the surface, where it freezes and forms a slab of ice. This slab is then moved onto a hot wire grid, where the ice is melted and removed from the evaporator. This type of evaporator is commonly used in ice-making machines that produce large quantities of ice for commercial purposes.

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83. What factor is not part of the know factors for using a pressure-temperture (PT) chart?

Explanation

The factor that is not part of the known factors for using a pressure-temperature (PT) chart is the humidity level. A PT chart is used to determine the relationship between the pressure and temperature of a refrigerant, which helps in troubleshooting and diagnosing issues in refrigeration systems. The ambient temperature, type of refrigerant, and vapor pressure are all important factors that need to be considered when using a PT chart, but the humidity level does not have a direct impact on the pressure and temperature relationship.

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84. During defrost, the heat pump system does not

Explanation

During the defrost cycle, the heat pump system temporarily stops operating in the cooling cycle to prevent the outdoor unit from freezing. This is necessary because when the outdoor temperature drops below a certain point, ice can accumulate on the outdoor coil, reducing the system's efficiency. To remove the ice, the heat pump switches to the defrost mode, where it temporarily reverses the refrigerant flow, allowing the outdoor coil to warm up and melt the ice. During this time, the system does not keep temperatures constant as it focuses on defrosting the outdoor unit.

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85. Which item is not an advantage of a multiple-compressor system?

Explanation

A multiple-compressor system offers several advantages, such as partial operation in case of failure of one unit, economy of operation at low loads, and control of refrigeration effect. However, lower humidity levels are not considered an advantage of a multiple-compressor system. This means that a multiple-compressor system does not have the capability to effectively reduce humidity levels in the environment.

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86. Approximately what percent of the evaporator tubing bundle is covered by the normal refrigerant charge in the centrifugal machine?

Explanation

The correct answer is 50. This means that approximately 50 percent of the evaporator tubing bundle is covered by the normal refrigerant charge in the centrifugal machine.

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87. Which type of ice-machine evaporator operates underwater?

Explanation

The correct answer is cell type. A cell type ice-machine evaporator operates underwater. This type of evaporator consists of individual cells that are submerged in water. These cells freeze the water to form ice and then release the ice into a storage bin. This design allows for efficient cooling and ice production.

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88. On systems that contain over how many pounds of refrigerant is passive recovery not authorized?

Explanation

Passive recovery is not authorized on systems that contain over 15 pounds of refrigerant. This means that for systems with a refrigerant quantity exceeding 15 pounds, a different method of recovery must be used instead of passive recovery.

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89. What is the line to inlet relationship of refrigerant vapor travel as it leaves the evaporator?

Explanation

The correct answer is "Suction to compressor." This means that the refrigerant vapor travels from the suction line to the compressor after leaving the evaporator. The suction line is responsible for carrying the low-pressure vapor from the evaporator to the compressor, where it is compressed and then sent to the condenser.

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90. What condition must exist before using a pressure-temperature (PT) chart?

Explanation

Before using a pressure-temperature (PT) chart, the condition that must exist is that the substance being analyzed must be in a saturated state. A saturated state means that the substance is in equilibrium with both its liquid and vapor phases at a specific temperature and pressure. This is important because the PT chart provides information about the relationship between pressure and temperature for a substance in its saturated state, allowing for accurate analysis and calculations.

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91. What is the maximum percent a refillable cylinder can be refilled with refrigerant?

Explanation

A refillable cylinder can be refilled with a maximum of 80% of refrigerant. This means that the cylinder should not be filled beyond this percentage to ensure safety and proper functioning. Filling it beyond this limit may cause issues such as overpressure or leakage, which can be dangerous. Therefore, it is important to adhere to the maximum refill percentage to maintain the cylinder's integrity and prevent any potential hazards.

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92. Normally the temperature of the water entering the condenser on a centrifugal air condtioning system should be about

Explanation

The correct answer is 85*F. In a centrifugal air conditioning system, the temperature of the water entering the condenser should be around 85*F. This is because the condenser is responsible for removing heat from the refrigerant, and the water temperature needs to be high enough to effectively transfer the heat from the refrigerant to the water. If the water temperature is too low, the condenser may not be able to remove enough heat, leading to reduced cooling efficiency. Conversely, if the water temperature is too high, it may cause damage to the condenser or other components of the system.

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93. To regulate the load on a water-cooled condenser, you should

Explanation

To regulate the load on a water-cooled condenser, controlling the tower fan is the correct answer. The tower fan helps to control the temperature of the water in the condenser by increasing or decreasing the airflow. By adjusting the speed or turning on/off the tower fan, the load on the condenser can be regulated effectively. Controlling the oil flow, circulating the oil back through the tank, or fully opening the recirculation control valve may have different purposes in the system but are not directly related to regulating the load on the water-cooled condenser.

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94. What can be used in place of thermostats and solenoid valves to control the temperatures in a multiple-temperature, multiple-evaporator system?

Explanation

Evaporator pressure regulating valves can be used in place of thermostats and solenoid valves to control the temperatures in a multiple-temperature, multiple-evaporator system. These valves regulate the pressure in the evaporator, which in turn controls the temperature. By adjusting the pressure, the evaporator pressure regulating valves can effectively control the temperature without the need for traditional thermostats and solenoid valves.

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95. What type of thermostatic expansion valve has a charged sensing bulb that presents the danger of flood-back?

Explanation

A thermostatic expansion valve with a charged sensing bulb that contains liquid presents the danger of flood-back. This is because the liquid-filled sensing bulb can cause the valve to open too quickly, leading to an excessive flow of refrigerant into the evaporator. This can result in liquid refrigerant entering the compressor, causing damage and potentially leading to flood-back.

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96. On a multi-evaporator system, the evaporator pressure regulating (EPR) valve will close when it reaches what temperature point?

Explanation

The EPR valve on a multi-evaporator system will close when it reaches the cutout temperature point. This means that when the temperature of the evaporator reaches a certain threshold, the EPR valve will shut off the flow of refrigerant to prevent the evaporator from getting too cold. This helps maintain the desired temperature and prevents potential damage to the system.

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97. Where does the compressed refrigerant vapor go during the heating cycle on a heat pump?

Explanation

During the heating cycle on a heat pump, the compressed refrigerant vapor goes into the evaporator. The evaporator is responsible for absorbing heat from the outside air or ground and transferring it to the refrigerant. As the refrigerant evaporates, it absorbs the heat energy, which is then carried to the compressor to be further compressed and released as hot air into the indoor space. Therefore, the evaporator plays a crucial role in the heating process of a heat pump.

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98. Which item does not indicate the cylinders are unloading when you are adjusting a hydraulic unloader mechanism?

Explanation

When adjusting a hydraulic unloader mechanism, the oil pressure should not excessively fluctuate. This means that the oil pressure should remain relatively stable during the adjustment process. If the oil pressure is fluctuating excessively, it indicates a problem with the unloader mechanism or the hydraulic system. Therefore, the correct answer is that the oil pressure will excessively fluctuate.

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99. What type of thermostatic expansion valve has a bulb that is charged with fluid that is different from the refrigerant in the system?

Explanation

A cross type thermostatic expansion valve has a bulb that is charged with fluid that is different from the refrigerant in the system. This design allows for better control and regulation of the refrigerant flow, as the bulb senses the temperature of the refrigerant and adjusts the valve accordingly. By using a different fluid in the bulb, the valve can accurately respond to changes in temperature and maintain the desired level of refrigerant flow.

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100. R–406a can be used to replace

Explanation

R-406a can be used to replace R-12 refrigerant. R-12, also known as dichlorodifluoromethane, is a hydrochlorofluorocarbon (HCFC) refrigerant that has been phased out due to its harmful effects on the ozone layer. R-406a, also known as azeotropic mixture, is a hydrofluorocarbon (HFC) refrigerant that does not harm the ozone layer. It has similar properties to R-12 and can be used as a drop-in replacement in existing systems designed for R-12.

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101. The thermostatic expansion valve maintains a fully active evaporator by

Explanation

The thermostatic expansion valve is responsible for regulating the flow of refrigerant into the evaporator coil. It maintains the proper amount of superheat by controlling the amount of refrigerant entering the evaporator. Superheat is the temperature of the refrigerant vapor above its boiling point, and it ensures that the refrigerant is completely vaporized before leaving the evaporator. By maintaining the proper amount of superheat, the thermostatic expansion valve ensures efficient and effective cooling by preventing liquid refrigerant from entering the compressor, which could cause damage.

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102. What type of alternative is refrigerant R–402A?

Explanation

Refrigerant R-402A is classified as a ternary blend. A ternary blend refers to a mixture or blend that consists of three different components or substances. In the case of R-402A, it is composed of three refrigerants: R-125, R-134a, and R-22. This combination of refrigerants allows R-402A to have specific properties and characteristics that make it suitable for certain cooling applications.

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103. The reciprocating refrigeration compressor is designed to remove

Explanation

The reciprocating refrigeration compressor is designed to remove vapor refrigerant from the evaporator and increase the pressure. This is because the compressor plays a crucial role in the refrigeration cycle by compressing the low-pressure vapor refrigerant from the evaporator and raising its pressure. This high-pressure vapor refrigerant is then sent to the condenser where it releases heat and condenses into a high-pressure liquid refrigerant. Therefore, the compressor's function is to increase the pressure of the vapor refrigerant from the evaporator, not from the condenser or the liquid refrigerant.

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104. When manual condensate drains are installed on an air receiver tank, they should be checked

Explanation

Manual condensate drains on an air receiver tank should be checked daily. This is because condensate, which is a mixture of water and oil, can accumulate in the tank and needs to be drained regularly to prevent damage to the tank and the compressed air system. Checking the drains daily ensures that any condensate buildup is promptly removed, maintaining the efficiency and performance of the system. Regular maintenance and monitoring also help to prevent potential issues such as corrosion and contamination.

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105. Which display-cabinet defrost method is limited to operating temperatures above 28 degrees?

Explanation

The compressor off-time defrost method is limited to operating temperatures above 28 degrees because it relies on the compressor being turned off to allow the ice to melt. At temperatures below 28 degrees, the compressor needs to run continuously to maintain the desired temperature inside the display cabinet, making it ineffective for defrosting.

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106. Where is the subcooler installed on a compound system?

Explanation

The subcooler is installed in the liquid line before the evaporator in a compound system. This placement allows the subcooler to cool down the liquid refrigerant before it enters the evaporator. By cooling the refrigerant, the subcooler helps to increase the efficiency of the evaporator and improve the overall performance of the system.

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107. The hydraulic cylinder unloader mechanism is designed to unload the cylinder by holding the

Explanation

The hydraulic cylinder unloader mechanism is designed to unload the cylinder by holding the suction valve open. This means that the suction valve remains open, allowing fluid to flow into the cylinder and relieve pressure. By keeping the suction valve open, the unloader mechanism prevents the cylinder from building up excessive pressure, ensuring safe and efficient operation.

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108. When solenoid valves are used in the suction line of a multi-evaporator system, what accessory must be installed?

Explanation

In a multi-evaporator system, when solenoid valves are used in the suction line, an accumulator must be installed as an accessory. An accumulator is a device that is used to collect and store excess refrigerant and oil from the evaporator. It helps to prevent liquid refrigerant from entering the compressor, which can cause damage. The accumulator also helps to ensure proper oil return to the compressor and maintains the efficiency of the system. Therefore, installing an accumulator is necessary when solenoid valves are used in the suction line of a multi-evaporator system.

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109. Which display-cabinet defrosting method has the advantage of not affested by changes in ambient temperature?

Explanation

The hot-wire defrosting method has the advantage of not being affected by changes in ambient temperature. This is because the hot-wire method uses an electrically heated wire to melt the ice on the display cabinet, rather than relying on external factors like gas or water. The hot-wire method provides more control over the defrosting process and ensures that it can be carried out consistently regardless of the surrounding temperature conditions.

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110. What accessory is added to the cascade system to increase its efficiency?

Explanation

A heat exchanger is added to the cascade system to increase its efficiency. A heat exchanger helps in transferring heat from one fluid to another, without them coming into direct contact. In a cascade system, the heat exchanger improves efficiency by transferring heat between the refrigerant in the high-stage and low-stage systems, allowing for better heat exchange and reducing energy consumption. This helps in optimizing the cooling process and improving overall system performance.

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111. How is the latent heat line shown on the pressure-enthalpy (PE) chart?

Explanation

The latent heat line is shown as horizontal on the pressure-enthalpy (PE) chart. This means that during a phase change, such as the transition from liquid to vapor, the enthalpy remains constant while the pressure changes. The horizontal orientation of the line indicates that the heat energy is being absorbed or released without any change in enthalpy, which is a characteristic of latent heat.

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112. Air compressors with operating pressures above 200 pounds per square inch gauge (psig) are required to have a hydrosatic test

Explanation

Air compressors with operating pressures above 200 pounds per square inch gauge (psig) are required to have a hydrostatic test every three years. This test is necessary to ensure the safety and integrity of the compressor. By subjecting the compressor to a hydrostatic test, any potential weaknesses or defects in the equipment can be identified and addressed before they lead to a failure or accident. Regular testing helps to maintain the reliability and efficiency of the compressor, ensuring that it continues to operate safely and effectively.

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113. In realtion to the curve, where does the refirgerant change of state take place on the pressure-enthalpy (PE) chart?

Explanation

The correct answer is "inside" because the question is asking about the location of the refrigerant change of state on the pressure-enthalpy (PE) chart. The change of state refers to the transition between liquid and vapor phases of the refrigerant. On the PE chart, this transition occurs within the boundaries of the curve, indicating that it takes place "inside" the curve.

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114. Which pressure control is designed to cut in on a rise in pressure and cut out on a drop in pressure?

Explanation

A low-pressure motor control is designed to cut in on a rise in pressure and cut out on a drop in pressure. This means that when the pressure drops below a certain threshold, the motor control will activate and start the motor, and when the pressure rises above a certain threshold, the motor control will deactivate and stop the motor. This control is typically used in systems where maintaining a specific pressure is critical, such as in HVAC systems or industrial processes.

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115. A retrofitted air-conditioning system still has the original capillary tube installed. In addition, the unit is undercharged with R–401A. In this configuration, the unit will operate satisfactorily in

Explanation

The retrofitted air-conditioning system still has the original capillary tube installed and is undercharged with R-401A. This configuration suggests that the system is designed to operate under relatively constant ambient conditions. The capillary tube is a fixed restriction device that controls the flow of refrigerant, and it is not designed to handle fluctuating load or ambient conditions. Additionally, the undercharging of refrigerant can affect the system's performance and efficiency, making it more suitable for relatively constant conditions where the load and ambient conditions remain relatively stable.

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116. You have plotted all the points for an operating refrigeration system on a pressure-enthalpy (PE) chart. This will not show you

Explanation

When plotting points on a pressure-enthalpy (PE) chart for an operating refrigeration system, it allows us to analyze and understand various aspects of the system's performance. However, the chart does not provide information about the amount of flash gas present in the system. Flash gas refers to the vaporization of refrigerant that occurs when its pressure drops below its saturation pressure. This phenomenon is not represented on a PE chart, making it unable to show the amount of flash gas.

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117. You have plotted all the points for an operating refrigeration system on a pressure-enthalpy (PE) chart. Which item below would you not do next?

Explanation

not-available-via-ai

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118. In a heat exchanger, the heat that is transferred comes from the

Explanation

In a heat exchanger, the heat that is transferred comes from the liquid line. This is because the liquid line carries the refrigerant in its liquid state, which has a higher temperature compared to the other lines. As the liquid refrigerant flows through the heat exchanger, it releases heat to the surrounding environment, thereby transferring the heat.

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119. On what basis should you check and clean the air filters used on air compressors?

Explanation

Air filters used on air compressors should be checked and cleaned on a weekly basis. This is because air filters play a crucial role in maintaining the efficiency and performance of the compressor. Regular cleaning ensures that the filters are free from dust, debris, and other contaminants that can clog the system and reduce airflow. By checking and cleaning the filters weekly, any potential issues can be identified and resolved promptly, preventing further damage to the compressor and ensuring optimal operation.

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120. Air-compressor receiver tanks should be inspected

Explanation

Air-compressor receiver tanks should be inspected every two years. This is because regular inspections are necessary to ensure the safety and efficiency of the tanks. By inspecting the tanks every two years, any potential issues or defects can be identified and addressed in a timely manner. This helps to prevent accidents, maintain proper functioning of the tanks, and prolong their lifespan. Additionally, regular inspections also help to comply with safety regulations and standards.

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121. Which pressure control is designed to operate from a pressure differential of the system?

Explanation

The oil-pressure safety control is designed to operate from a pressure differential of the system. This control is responsible for monitoring the oil pressure in a system and ensuring it stays within safe limits. If the pressure drops below or exceeds the specified range, the safety control will activate and trigger an alarm or shut down the system to prevent any damage or accidents.

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122. The safety devices used on air compressors should be checked

Explanation

The safety devices used on air compressors should be checked annually to ensure their proper functioning and to prevent any potential accidents or malfunctions. Regular inspections allow for timely identification of any issues or wear and tear that may have occurred over time. By conducting annual checks, any necessary repairs or replacements can be made, ensuring the continued safe operation of the air compressor.

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123. Which type of cooler is generally used in the common water cooler?

Explanation

Shell-and-coil coolers are generally used in common water coolers. This type of cooler consists of a coil inside a shell. The water flows through the coil, while the cooling medium, usually air, circulates around the coil inside the shell. This design allows for efficient heat transfer between the water and the cooling medium, resulting in effective cooling of the water. Shell-and-coil coolers are commonly used in water coolers due to their compact size, high heat transfer efficiency, and ease of maintenance.

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124. What can be used to control a single-temperature, multiple-evaporator system?

Explanation

A low-pressure motor control can be used to control a single-temperature, multiple-evaporator system. This control helps regulate the pressure within the system, which in turn controls the temperature. By adjusting the motor control, the system can maintain the desired temperature by controlling the evaporation process. This allows for precise temperature control in each evaporator, ensuring that the system operates efficiently and effectively.

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Refrigerants containing chlorine are said to destroy
The best critera to follow when you are inspecting equipment are
You are retrofitting a system that does not have a receiver. To do the...
Complete vaporization in an evaporator occurs at point
What must you do to the power before you perform a preoperational...
Which major component is considered to be the "heart" of the...
Two different metals that are bonded into a strip or coil are called
The advantage of an air-cooled condenser is
Which evaporator operating condition uses air circulation to aid in...
All moving parts on an air compressor should have
Where are the coldest rooms located in a permanent cold-storage plant?
What program is designed to keep HVAC/R equipment in operational...
The disadvantage of water-cooled condensers is
A good refrigerant oil will have
The direct-expansion evaporator picks up or absorbs heat directly from...
What term refers to how hot or cold a substance is?
Which refrigerant oil is designed for use with the new ternary blend...
Cleaning a refrigerant at the job site or at a local service shop is...
Which heat pump component prevents liquid refrigerant from entering...
How does the rotary compressor compress the refrigerated vapor?
What type of rotary compressor has the blade set into the cylinder?
An ice-cream cabinet is similar to a
Which of these refrigerants has an ozone depletion rating of zero?
How much of the refrigerant charge should a receiver hold?
What device is used to prevent liquid refrigerant from entering the...
Which packaged unit normally uses only one fan motor?
What is a big problem with humidity control equipment?
Which processes take place inside the condenser?
Which component is installed at the inlet of the evaporator?
To create the required pressure drop, the capillary tube uses a...
When the compressor air intake is piped to the outside, it should be
The float assembly in an oil separator is activated by the
Which refrigeration compressor is equipped with pistons and connecting...
You are retrofitting a system with an alternative refrigerant and you...
What must be balanced to distribute the load as equally as possible...
What triggers a refrigeration unit to cycle on or off?
What is the term for a refrigeration unit to operate or cycle on?
The Environmental Protection Agency (EPA) has developed a Significant...
Which organization requires that a comprehensive risk assessment be...
Which compressor type is used with refrigerants that have a large gas...
On a centrifugal machine, the refrigerant flows from the first-stage...
What is the maximum fine and jail sentence that service technicians...
What prevents direct impact of refrigerant vapors on the tubing bundle...
In a multistage air-compressor installation, what is used to...
The receiver thanks used on air compressor are designed to be
To help ensure that the proper refrigerant and lubricant will be used...
Which desiccant is the most popular and can be left in the system...
Temperature glide in an zeotropic refrigerant means that the...
On Type II systems, what level of evacuation in the isolated component...
When conducting an operational check of the mechanical part of a...
Commercial and industrial systems with leaks exceeding what percent...
Heat that is picked up in the refrigeration system is rejected at the
R–401A is not a suitable alternative refrigerant for
What type of heat when added to a substance causes a measured...
How is the capillary tube in a system affected by the refrigerant...
Where do you install a sight glass and/or moisture indicator in a...
What do filter-driers not remove from a refrigeration system?
Which type piston can suction gas pass through?
In which major component does absorbed heat cause liquid refrigerant...
The purge unit on a centrifugal machine is not designed to
When polyolester oil is used in place of mineral oil during a retrofit...
Air intake filters used on air compressors are designed to prevent
Which of these refrigerants is colorless and has a very pronounced...
During retrofitting, which component might have to be reset to...
Which cooler is used exclusively to cool liquids?
The ultralow-temperature classification begins at
In relation to the curve, where is the liquid refrigerant shown on the...
Which evaporator type is designed to maintain an even temperature...
Proportionately which refrigerator has the biggest freezer...
The connecting point of a cascade system is
Which type of compressor uses an orbiting motion for compression?
R–401A and B can be described as a/an
Which type of water-cooled condenser has removable heads that...
How many air-compressor starts per hour would require a constant...
The economizer on a centrifugal machine prevents liquid refrigerant...
What is it called when two or more compressors are piped in series to...
During equipment cooling, humidity cannot be added to the air by
In which two parts of a refrigeration system does a pressure change...
Which alternative replacement for R–502 is a patented azeotrope?
Which pressure control has contacts that open on a rise in pressure?
What type maintenance action do you perform on operating HVAC/R...
Which type of ice-machine evaporator produces a slab of ice that is...
What factor is not part of the know factors for using a...
During defrost, the heat pump system does not
Which item is not an advantage of a multiple-compressor system?
Approximately what percent of the evaporator tubing bundle is covered...
Which type of ice-machine evaporator operates underwater?
On systems that contain over how many pounds of refrigerant is passive...
What is the line to inlet relationship of refrigerant vapor travel as...
What condition must exist before using a pressure-temperature (PT)...
What is the maximum percent a refillable cylinder can be refilled with...
Normally the temperature of the water entering the condenser on a...
To regulate the load on a water-cooled condenser, you should
What can be used in place of thermostats and solenoid valves to...
What type of thermostatic expansion valve has a charged sensing bulb...
On a multi-evaporator system, the evaporator pressure regulating (EPR)...
Where does the compressed refrigerant vapor go during the heating...
Which item does not indicate the cylinders are unloading when you are...
What type of thermostatic expansion valve has a bulb that is charged...
R–406a can be used to replace
The thermostatic expansion valve maintains a fully active evaporator...
What type of alternative is refrigerant R–402A?
The reciprocating refrigeration compressor is designed to remove
When manual condensate drains are installed on an air receiver tank,...
Which display-cabinet defrost method is limited to operating...
Where is the subcooler installed on a compound system?
The hydraulic cylinder unloader mechanism is designed to unload the...
When solenoid valves are used in the suction line of a...
Which display-cabinet defrosting method has the advantage of not...
What accessory is added to the cascade system to increase its...
How is the latent heat line shown on the pressure-enthalpy (PE) chart?
Air compressors with operating pressures above 200 pounds per square...
In realtion to the curve, where does the refirgerant change of state...
Which pressure control is designed to cut in on a rise in pressure and...
A retrofitted air-conditioning system still has the original capillary...
You have plotted all the points for an operating refrigeration system...
You have plotted all the points for an operating refrigeration system...
In a heat exchanger, the heat that is transferred comes from the
On what basis should you check and clean the air filters used on air...
Air-compressor receiver tanks should be inspected
Which pressure control is designed to operate from a pressure...
The safety devices used on air compressors should be checked
Which type of cooler is generally used in the common water cooler?
What can be used to control a single-temperature, multiple-evaporator...
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