3e151 CDC Set C/P Volume 1

A thermostatic expansion valve with a charged sensing bulb that presents the danger of flood-back is a "Liquid" type. In this type of valve, the sensing bulb is filled with a liquid charge, which can cause flood-back if not properly controlled. Flood-back occurs when liquid refrigerant enters the compressor, leading to potential damage. Therefore, a liquid type thermostatic expansion valve requires careful monitoring and control to prevent flood-back.

The EPA's Significant New Alternatives Policy (SNAP) Program is developed to assess the risks that alternative refrigerants pose to human health and the environment. The program aims to determine whether the alternative refrigerant is safe and does not have adverse effects on human health or the environment. By evaluating the risks associated with alternative refrigerants, the EPA can make informed decisions on which refrigerants can be used as substitutes for harmful substances, promoting environmental protection and public health.

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 can be condensed into a liquid state. Therefore, the correct answer is "vapor refrigerant from the evaporator and increase the pressure."

The side-by-side refrigerator has the biggest freezer compartment compared to the other options. This type of refrigerator is designed with the freezer on one side and the refrigerator on the other side, providing equal space for both compartments. In contrast, the top-freezer refrigerator has a smaller freezer compartment located on the top, while the single-door refrigerator and bottom-freezer refrigerator have even smaller freezer compartments. Therefore, the side-by-side refrigerator offers the largest freezer space proportionately.

The absorbed heat causes the liquid refrigerant to boil in the evaporator. The evaporator is responsible for absorbing heat from the surroundings, such as the air in a room, and this heat causes the liquid refrigerant to evaporate and turn into a gas. This gas then travels to the compressor where it is pressurized and sent to the condenser to release the heat before returning to the evaporator to repeat the cycle.

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. Sand particles are too large and heavy to be captured by the filter-drier. Therefore, while filter-driers are important for maintaining the cleanliness and efficiency of a refrigeration system, they do not have the ability to remove sand particles.

The baffle plate prevents direct impact of refrigerant vapors on the tubing bundle of the centrifugal system condenser. It acts as a barrier between the vapors and the tubing, redirecting the flow and preventing any potential damage or corrosion that could occur from direct contact.

A rotary compressor with a stationary blade has the blade set into the cylinder. This means that the blade remains fixed in position while the cylinder rotates, allowing for the compression of air or gas. The stationary blade helps to create a seal and control the flow of the medium being compressed. This type of compressor is commonly used in various applications, including refrigeration and air conditioning systems.

Centrifugal compressors are used with refrigerants that have a large gas volume. These compressors are specifically designed to handle high flow rates and are efficient in compressing large volumes of gas. They work by converting kinetic energy into pressure energy, making them suitable for applications where a large gas volume needs to be compressed, such as in industrial refrigeration systems or large-scale air conditioning units.

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. The forced convection helps to prevent any temperature variations, ensuring that all areas of the refrigerated space are kept at the desired temperature. This is particularly important in applications where temperature consistency is critical, such as in food storage or pharmaceuticals.

Labeling the components and system is the correct answer because it helps ensure that the proper refrigerant and lubricant will be used in the future. By clearly labeling the components and system, technicians can easily identify the correct type and amount of refrigerant and oil to use, preventing any potential mistakes or accidents. This labeling system also helps in maintaining the system by providing important information about the components and their requirements, making it easier for future maintenance and repairs.

The maximum percent a refillable cylinder can be refilled with refrigerant is 80%. This means that the cylinder can be filled up to 80% of its total capacity with refrigerant. Refilling the cylinder beyond this limit may cause safety issues or damage to the cylinder. It is important to follow this guideline to ensure proper functioning and safety when handling refrigerants.

Silica gel is the most popular desiccant that can be left in the system indefinitely. Silica gel is a highly porous substance that has a strong affinity for water molecules, making it an effective moisture absorber. It is widely used in various industries and applications, such as in food packaging, electronics, and pharmaceuticals. Its popularity stems from its ability to maintain its moisture-absorbing properties even after it becomes saturated, allowing it to be reused or regenerated easily. Additionally, silica gel is non-toxic and chemically inert, making it safe to use in various environments.

Alkyl benzene oil is designed for use with the new ternary blend refrigerants. It is a synthetic oil that offers excellent lubricity and stability, making it suitable for use in refrigeration systems. Alkyl benzene oil is compatible with various refrigerants, including the new ternary blend refrigerants, and helps to ensure efficient and reliable operation of the system.

Saturating the coils with warm water cannot add humidity to the air during equipment cooling because the water would not evaporate into the air. In order to add humidity, the water needs to evaporate and become water vapor. However, saturating the coils with warm water would simply result in the coils being wet, without any evaporation occurring. Therefore, this method does not add humidity to the air.

A trunk piston is designed with a cavity or trunk in the center, allowing the gas to pass through it. This type of piston is commonly used in internal combustion engines, where the gas needs to flow through the piston during the intake stroke. The trunk design enables efficient suction of the gas into the combustion chamber. Therefore, a trunk piston is the correct type of piston that allows gas to pass through.

The liquid refrigerant is shown on the left side of the pressure-enthalpy (PE) chart. This is because the left side of the chart represents low pressure and low enthalpy conditions, which are characteristic of the liquid phase of the refrigerant. As the refrigerant evaporates and transitions into a gas, it moves towards the right side of the chart where the pressure and enthalpy values increase. Therefore, the correct answer is "Left".

A horizontal plate ice-machine evaporator produces a slab of ice that is moved onto a hot-wire grid. The horizontal plate design allows for the ice to be formed in a flat, even layer on the evaporator surface. Once the ice is fully formed, it is then moved onto a hot-wire grid where it is cut into individual slabs. This design is commonly used in ice-making machines for commercial and industrial applications where large quantities of ice are needed.

The EPR valve on a multi-evaporator system will close when it reaches the cutout temperature point. This means that when the evaporator pressure reaches a certain high temperature, the EPR valve will close to prevent further increase in pressure. This helps to maintain the desired operating conditions and prevent damage to the system.

When two or more compressors are piped in series to one another, it is called compounding. This means that the output of the first compressor is fed into the input of the second compressor, and so on. This allows for increased compression and pressure in the system, as each compressor adds to the overall compression. Compounding is commonly used in industrial applications where high levels of compression are required.

During the heating cycle on a heat pump, the compressed refrigerant vapor goes to the evaporator. The evaporator is responsible for absorbing heat from the surrounding air or water, causing the refrigerant to evaporate and turn into a gas. This gas then travels to the compressor, where it is further compressed and heated, eventually releasing the heat into the desired space. So, the evaporator is the correct answer as it is the component where the refrigerant vapor goes during the heating cycle.

Air intake filters used on air compressors are designed to prevent unnecessary wear by filtering out particles and contaminants from the air before it enters the compressor. These particles can cause abrasion and damage to the internal components of the compressor, leading to increased wear and reduced performance. By keeping the air clean, the intake filter helps to maintain the efficiency and longevity of the compressor by reducing the risk of unnecessary wear on its parts.

When retrofitting a system with an alternative refrigerant, replacing the capillary tube with one having greater resistance and longer length is the correct approach. A capillary tube controls the flow of refrigerant into the evaporator coil. By increasing the resistance and length of the capillary tube, the flow rate of the refrigerant is reduced. This is necessary when using an alternative refrigerant, as it may have different pressure and flow characteristics compared to the original refrigerant. Adjusting the capillary tube in this way ensures proper functioning of the system with the new refrigerant.

The refrigerant change of state takes place inside the curve on the pressure-enthalpy (PE) chart. This means that the change from liquid to vapor or vice versa occurs within the boundaries of the curve, indicating a transition between different states of the refrigerant.

The known factors for using a pressure-temperature (PT) chart include ambient temperature, type of refrigerant, and vapor pressure. Humidity level is not a part of the known factors for using a PT chart. The PT chart is used to determine the relationship between pressure and temperature for a specific refrigerant, and humidity level does not directly affect this relationship.

The Baudelot cooler is used exclusively to cool liquids. This type of cooler is specifically designed to efficiently cool liquids by circulating them through a series of tubes or coils. The liquid flows through the tubes while a cooling medium, such as water or air, passes over the exterior of the tubes, extracting heat and cooling the liquid. This design allows for effective heat transfer and cooling of the liquid, making the Baudelot cooler ideal for applications where liquid cooling is required.

When making minor repairs on Type II systems, such as replacing a filter-drier or a strainer, the isolated component must be evacuated to a level of 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 there are no contaminants or moisture left in the system, which could affect its performance. Evacuating the component to 0 psig helps maintain the efficiency and reliability of the system.

R-401A is not a suitable alternative refrigerant for residential air conditioners because it is primarily designed for low-temperature applications, such as walk-in coolers and supermarket display cases. Residential air conditioners require a refrigerant that is specifically formulated for higher operating temperatures and pressures. Using R-401A in residential air conditioners could lead to inefficient cooling, potential damage to the system, and increased energy consumption.

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

The receiver tanks used on air compressors are designed to be air storage tanks. These tanks store compressed air that is generated by the compressor, allowing for a steady supply of air to be available for use when needed. They help to regulate the pressure and flow of the compressed air, ensuring that it is readily available for various applications.

Manual condensate drains on an air receiver tank should be checked daily to ensure that any accumulated condensate is properly drained. Regular and frequent checks are necessary to prevent the buildup of excess condensate, which can lead to corrosion and damage to the tank and the compressed air system. By checking the drains daily, any issues or blockages can be promptly addressed, ensuring the efficient operation of the system.

A scroll compressor uses an orbiting motion for compression. It consists of two spiral-shaped scrolls, one fixed and one orbiting, which creates 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, making scroll compressors quieter and more reliable compared to other types of compressors.

Commercial and industrial systems with leaks exceeding 35% per year will require repair. This means that if the leaks in the system exceed 35% of the total volume per year, it is necessary to fix the leaks. This is because leaks can lead to significant loss of resources and can also cause damage to the system itself. Therefore, it is important to address and repair any leaks that exceed this threshold to ensure the proper functioning and efficiency of the commercial or industrial system.

Plotting all the points for an operating refrigeration system on a pressure-enthalpy (PE) chart allows us to analyze various properties and characteristics of the system. However, it does not provide information about the gained system pressure. The gained system pressure refers to the increase in pressure that occurs within the refrigeration system due to factors such as resistance in the flow of refrigerant or the operation of compressors. This information is not directly visible or measurable from the pressure-enthalpy chart.

The economizer on a centrifugal machine prevents liquid refrigerant from entering the compressor through the use of eliminator baffles. These baffles are designed to 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 economizer helps to maintain the efficiency and performance of the centrifugal machine.

A heat exchanger is added to the cascade system to increase its efficiency. A heat exchanger is a device that transfers heat between two or more fluids, allowing them to exchange thermal energy. In a cascade system, the heat exchanger helps to improve the efficiency by transferring heat from the high-temperature refrigerant to the low-temperature refrigerant. This allows for a more efficient transfer of heat and helps to optimize the cooling process. By using a heat exchanger, the cascade system can effectively utilize the temperature difference between the two refrigerants, resulting in improved overall efficiency.

A multiple-compressor system is designed to have multiple compressors operating in parallel, which allows for partial operation in case of failure of one unit. This redundancy ensures that the system can continue to function even if one compressor fails. Economy of operation at low loads is also an advantage of a multiple-compressor system, as it allows the system to adjust its capacity based on the demand, resulting in energy savings. Control of refrigeration effect is another advantage, as it allows for precise temperature control. However, lower humidity levels are not an advantage of a multiple-compressor system.

The ultralow-temperature classification begins at -20*F because this temperature is significantly lower than the other options provided (-10*F, -5*F, and 0*F). Ultralow temperatures refer to extremely cold conditions, and -20*F falls within this range.

The hydraulic cylinder unloader mechanism is designed to unload the cylinder by holding the suction valve open. This means that the mechanism allows the fluid to flow out of the cylinder through the suction valve, relieving the pressure and unloading the cylinder. By keeping the suction valve open, the mechanism ensures that the fluid can flow freely and efficiently, preventing any potential damage or malfunction in the cylinder.

Performing an operational check on an operating HVAC/R system involves assessing its functionality and performance. This includes testing the various components, such as the thermostat, fans, motors, and refrigerant levels, to ensure they are working properly. By conducting this check, any issues or malfunctions can be identified and addressed promptly, helping to maintain the system's efficiency and prevent potential breakdowns. It is an essential maintenance action to ensure the smooth operation of the HVAC/R system.

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 ensures that the motor only operates within the desired pressure range, preventing any damage or malfunction due to excessive pressure.

Hot-wire defrosting method has the advantage of not being affected by changes in ambient temperature. This is because hot-wire defrosting relies on an electric resistance wire that heats up to melt the ice on the display-cabinet. The temperature of the wire is controlled independently of the ambient temperature, ensuring consistent and efficient defrosting regardless of external conditions.

When conducting an operational check of the mechanical part of an HVAC/R system, it is important to check the system pressures. This is because the system pressures indicate whether the system is functioning properly and if there are any issues such as leaks or blockages. By monitoring the system pressures, technicians can ensure that the system is operating at the correct levels and make any necessary adjustments or repairs. Checking the water levels, cleanliness of coils, and proper lubrication are also important maintenance tasks, but they are not directly related to the operational check of the mechanical part of the system.

The compressor air intake should be six feet above the ground to prevent it from drawing in debris, dust, or water that may be present on the ground. Placing it at this height ensures that the air being sucked into the compressor is clean and free from any potential contaminants that could damage the equipment or affect its performance.

In this configuration, the retrofitted air-conditioning system with the original capillary tube and undercharged with R-401A will operate satisfactorily in relatively constant ambient conditions. This means that the system is designed to work efficiently in conditions where the temperature and humidity of the surrounding environment remain relatively stable. Fluctuating ambient conditions may cause the system to struggle to maintain the desired temperature and humidity levels, leading to reduced performance and potential issues. Therefore, it is important to ensure that the system is properly sized and charged for the specific ambient conditions it will be operating in.

A cross type thermostatic expansion valve has a bulb that is charged with fluid that is different from the refrigerant in the system. This allows for more precise control of the refrigerant flow as the fluid in the bulb expands and contracts with temperature changes, providing accurate feedback to the valve. This type of valve is commonly used in systems where precise temperature control is required.

To regulate the load on a water-cooled condenser, controlling the tower fan is the correct answer. The tower fan helps in dissipating the heat from the condenser by drawing air through the cooling tower. By controlling the speed or operation of the tower fan, the amount of air passing through the tower can be adjusted, thereby regulating the cooling effect on the condenser. This allows for efficient cooling and helps maintain the desired temperature and load on the condenser.

R-717, also known as ammonia, is a colorless refrigerant with a very pronounced odor. It is commonly used in industrial refrigeration systems due to its high efficiency and low environmental impact. Ammonia has a strong smell that is easily detectable, even in small concentrations, which makes it a safe choice as any leaks can be quickly identified.

R-401A and B are described as hydrofluorocarbon (HFC)-based alternatives. This means that they are alternatives that use HFCs as their primary components. HFCs are a type of synthetic refrigerant that does 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.

The temperature of the water entering the condenser on a centrifugal air-conditioning system should be around 85°F. This temperature is ideal for the condenser to effectively remove heat from the refrigerant and cool it down. If the water temperature is too low, it may not provide enough cooling capacity, while if it is too high, it may not effectively remove heat from the refrigerant. Therefore, 85°F is the optimal temperature for efficient cooling in a centrifugal air-conditioning system.

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

R-406a can be used to replace R-12 because R-12 is a hydrochlorofluorocarbon (HCFC) refrigerant that has been phased out due to its harmful effects on the ozone layer. R-406a is a blend of refrigerants that does not contain any ozone-depleting substances and has similar properties to R-12. Therefore, it can be used as a suitable alternative to R-12 in various refrigeration and air conditioning systems.

Creating a database system to track all readings would not be the next step because the question asks what you would NOT do next. The previous options involve comparing the data with the manufacturer, experimenting with changing values, and filing the data for future reference. Therefore, creating a database system is not the next logical step in this scenario.

The safety devices used on air compressors should be checked annually to ensure their proper functioning and to prevent any potential hazards or accidents. Regular inspections and maintenance help identify any issues or wear and tear that may have occurred over time. By checking the safety devices annually, operators can address any necessary repairs or replacements, ensuring the continued safety and efficiency of the air compressor system.

When adjusting a hydraulic unloader mechanism, the cylinders should indicate that they are unloading. This means that the pressure inside the cylinders should decrease, which would cause the amperage to drop, the suction pressure to rise, and the sound of the compressor to change. However, the oil pressure should not excessively fluctuate during this process. Therefore, the item that does not indicate the cylinders are unloading is "The oil pressure will excessively fluctuate."

The question is asking for the number of air-compressor starts per hour that would require a constant speed control. A constant speed control is typically used when there is a need for a consistent and steady speed. In the context of air compressors, it is likely that a constant speed control would be required when there is a high demand for compressed air. Out of the given options, 13 starts per hour would indicate a relatively high demand and would therefore require a constant speed control.

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Refrigerant R-402A is classified as a ternary blend. A ternary blend refers to a mixture that consists of three different components. In the case of R-402A, it is composed of three refrigerants - R-125, R-134a, and R-600a. This combination of refrigerants provides specific properties and performance characteristics suitable for certain cooling applications.

The compressor off-time defrost method is limited to operating temperatures above 28 degrees because it relies on turning off the compressor to allow the accumulated ice to melt. This method is not effective at lower temperatures because the compressor needs to be running to maintain the desired temperature inside the display cabinet. Therefore, it is only suitable for defrosting at higher temperatures where turning off the compressor for a period of time will not cause the temperature to drop too much.

The subcooler is installed in the liquid line before the evaporator. This placement allows the subcooler to cool down the refrigerant even further before it enters the evaporator. By removing additional heat from the refrigerant, the subcooler helps to increase the system's overall efficiency and improve the cooling capacity.

The purge unit on a centrifugal machine is specifically designed to remove contaminated oil. It is not intended to remove air, water, or recover refrigerant. Its main function is to eliminate oil that has been contaminated with impurities or particles, ensuring the efficiency and proper functioning of the centrifugal machine.

When solenoid valves are used in the suction line of a multi-evaporator system, an accumulator must be installed. An accumulator is a device that is used to store excess refrigerant and oil from the evaporator during periods of low load or low refrigerant flow. It helps to prevent liquid refrigerant from entering the compressor, which can cause damage. By installing an accumulator, it ensures that only vapor refrigerant is delivered to the compressor, improving the overall efficiency and performance of the system.

The connecting point of a cascade system is a condenser-evaporator. In a cascade system, two refrigeration cycles are used, with one cycle operating at a higher temperature and the other at a lower temperature. The condenser-evaporator acts as the connection point between the two cycles, allowing the transfer of heat from the higher temperature cycle to the lower temperature cycle. This allows for efficient cooling at multiple temperature levels in applications such as industrial refrigeration or cryogenic cooling.

During defrost, the heat pump system does not keep temperatures constant. This is because defrosting involves melting any ice or frost that has accumulated on the outdoor unit. To do this, the system temporarily switches to a heating cycle, where the outdoor fan is turned off and electric heat may be used to warm the outdoor unit and melt the ice. As a result, the system cannot maintain constant temperatures during defrost.

In a heat exchanger, the heat that is transferred comes from the liquid line. The liquid line carries the condensed refrigerant from the condenser to the expansion valve. As the high-pressure liquid refrigerant flows through the liquid line, it releases heat to the surrounding environment, which allows it to change from a high-pressure liquid to a low-pressure liquid-vapor mixture. This heat transfer process is essential for cooling down the refrigerant and preparing it for the next stage of the refrigeration cycle.

The correct answer is "Cell type" because cell type evaporators are designed to operate underwater. These evaporators consist of individual cells or compartments that are submerged in water, allowing for efficient heat transfer and ice production. This design is commonly used in commercial ice machines to produce large quantities of ice quickly. Tube type evaporators, on the other hand, operate above water and use a series of tubes to circulate refrigerant and extract heat. Vertical plate and horizontal plate evaporators are also not designed to operate underwater.

The correct answer is Shell-and-coil. In a common water cooler, a shell-and-coil type of cooler is generally used. This type of cooler consists of a coil of tubing placed inside a shell. The water flows through the coil while the cooling medium, such as refrigerant or chilled water, circulates around the coil in the shell. This design allows for efficient heat transfer between the water and the cooling medium, resulting in the cooling of the water in the cooler.

The oil-pressure safety control is designed to operate from a pressure differential of the system. This means that it is specifically designed to monitor and control the oil pressure in a system, ensuring that it stays within safe limits. It is likely used in systems where maintaining proper oil pressure is crucial for the safe and efficient operation of equipment or machinery.

The latent heat line is shown as horizontal on the pressure-enthalpy (PE) chart. This means that during a phase change, such as vaporization or condensation, the enthalpy remains constant while the pressure changes. This indicates that the heat transfer is occurring at a constant temperature, as the enthalpy is a measure of the heat content of a substance.

Air filters used on air compressors should be checked and cleaned on a weekly basis to ensure optimal performance and prevent any potential damage to the compressor. Regular maintenance of the air filters helps to remove dust, debris, and other contaminants from the air, allowing for clean and efficient air flow. By checking and cleaning the filters weekly, any build-up of dirt or clogs can be identified and resolved promptly, ensuring that the compressor operates effectively and prolonging its lifespan.

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 separate thermostats and solenoid valves. This provides a more efficient and streamlined method of temperature control in such systems.

Air compressors with operating pressures above 200 pounds per square inch gauge (psig) are required to have a hydrostatic test every three years. This means that the compressors need to undergo a pressure test to ensure their safety and reliability. By conducting the test every three years, any potential issues or weaknesses in the compressor can be identified and addressed, reducing the risk of accidents or malfunctions. Regular testing also helps to maintain the efficiency and performance of the compressors, ensuring they continue to operate effectively.

A low-pressure motor control can be used to control a single-temperature, multiple-evaporator system. This control regulates the motor speed based on the low-pressure conditions in the system, ensuring that the evaporators are operating at the desired temperature. By adjusting the motor speed, the control can effectively manage the cooling capacity of the system and maintain the desired temperature in each evaporator. This allows for efficient and precise control of the system, ensuring optimal performance and temperature control.

Air-compressor receiver tanks should be inspected every two years. This frequency allows for regular monitoring of the tank's condition and ensures that any potential issues or defects are identified and addressed in a timely manner. Inspections help to prevent safety hazards, such as leaks or structural failures, and ensure the efficient operation of the air compressor system. By conducting inspections every two years, maintenance and repair activities can be planned and implemented effectively, reducing the risk of unexpected breakdowns and costly downtime.