Acr 109 Final Exam Review

When tubing is cut with a tubing cutter, it creates a burr, which is a rough edge or ridge on the inside of the tube. This burr can cause problems in the operation of the system because it decreases the inside diameter of the tube. A decrease in the inside diameter can restrict the flow of fluids or gases through the tube, leading to reduced efficiency or even complete failure of the system. Therefore, the statement is true.

As a refrigeration technician, it is important to have a warm coat and gloves in your truck even in the summer because you may need to work in cold environments such as walk-in freezers or refrigerated rooms. These protective clothing items will help you stay warm and comfortable while carrying out your job responsibilities.

The statement suggests that K-type copper is heavy duty with a thick tubing wall. This implies that K-type copper is designed to withstand heavy-duty usage and has a thicker wall compared to other types of copper tubing. Therefore, the correct answer is True.

Locking out the panel with a padlock and keeping the key with you is a necessary safety practice for a technician. This practice ensures that unauthorized individuals cannot access the panel, preventing potential accidents or injuries. By having exclusive control over the key, the technician can ensure that no one can tamper with the equipment while they are working on it. This helps to protect both the technician and others who may be in the vicinity from any potential electrical hazards.

If liquid R-22, which is a refrigerant, comes in contact with your hand, it can cause frostbite. This is because R-22 is extremely cold and can lower the temperature of your skin rapidly, causing damage to the tissues and blood vessels. Therefore, it is important to handle refrigerants like R-22 with caution and avoid any direct contact to prevent frostbite or other injuries. Additionally, it is mentioned that releasing refrigerant into the atmosphere is an illegal procedure, highlighting the importance of proper handling and disposal of refrigerants.

When installing a refrigeration system, it is recommended to connect the piping with as few joints as possible. This is because each joint introduces the risk of potential leaks, which can lead to refrigerant leakage and system inefficiencies. By minimizing the number of joints, the system's overall reliability and performance can be improved. Additionally, reducing the number of joints simplifies maintenance and reduces the overall cost of installation. Therefore, it is advisable to connect the piping with as few joints as possible when installing a refrigeration system.

The statement explains that DWV copper stands for drain, waste, and vent, and it is a lightweight copper that is not commonly used in the HVACR industry for refrigerant-carrying applications. This implies that the statement is true, as it suggests that DWV copper is not typically used for refrigerant-carrying purposes in the HVACR industry.

To ensure the proper functioning of an oxygen cylinder regulator, it is crucial to ensure that there is no presence of oil residue. Oil residue can contaminate the oxygen supply and pose a serious risk to the user. Therefore, it is essential to maintain a clean and oil-free environment to guarantee the safe and effective operation of the regulator.

L-type copper is considered medium weight and is used most frequently. This means that it is neither too heavy nor too light, making it suitable for a wide range of applications. Due to its versatility, it is commonly used in various industries such as construction, plumbing, and electrical wiring. Therefore, the statement "L-type copper is considered medium weight and is used most frequently" is true.

Air entering a refrigerant system can cause several issues, including reduced cooling efficiency and increased energy consumption. However, one of the most serious consequences is compressor failure. The compressor is a vital component of the refrigerant system, responsible for compressing the refrigerant and maintaining the flow. When air enters the system, it can mix with the refrigerant, forming air bubbles. These bubbles can disrupt the flow of refrigerant and cause the compressor to work harder, leading to overheating and ultimately failure. Therefore, it is crucial to prevent air from entering the refrigerant system to avoid compressor failure.

To minimize the chance of electrical shock when performing electrical work in an area with a damp or wet floor, it is important to take multiple precautions. Placing a rubber mat on the floor helps to insulate against electrical current, reducing the risk of shock. Using a wooden ladder instead of a metal one also provides insulation. Additionally, wearing insulated boots and gloves further protects against electrical shock by preventing direct contact with the floor or any live wires. Therefore, all of the above options should be followed to minimize the chance of electrical shock.

The given statement is true because it states that the maximum recommended pressure for leak testing is 150 psig on the low-pressure side of the system. This means that when conducting a leak test, it is advised to maintain the pressure below or equal to 150 psig on the low-pressure side to ensure accurate results and avoid any potential damage or failure of the system.

The oil in a vacuum pump should be changed after each use because during operation, the oil can become contaminated with various substances such as moisture, dirt, and chemicals. These contaminants can degrade the performance of the pump and potentially cause damage. Changing the oil after each use ensures that the pump operates at its optimal level and prolongs its lifespan.

The statement is true because an air-acetylene torch with a twist tip method allows for effective mixing of air and acetylene, which can generate a high temperature flame suitable for high temperature soldering. Additionally, by adjusting the ratio of air and acetylene, the torch can also produce a low temperature flame for low temperature soldering applications. Therefore, this type of torch is versatile and can be used for both low and high temperature soldering.

The statement indicates that M, which is a lightweight copper, is not commonly used in our industry. Therefore, the correct answer is True, implying that M is indeed not commonly used in the industry.

Fires that involve ordinary materials such as paper, cardboard, and wood are classified as type A. Type A fires are commonly referred to as ordinary combustible fires and are the most common type of fire. These fires can be easily extinguished with water or other common extinguishing agents.

A double insulated drill generally has a plastic case with the electrical connections and motor insulated within the tool. This means that the drill is designed in a way that eliminates the need for a ground wire or grounding. The plastic case acts as a barrier to prevent any electrical current from reaching the user, making it safer to use. The insulation within the tool ensures that there is no contact between the electrical components and the outer casing, further reducing the risk of electric shock.

The correct answer is American national standard. A.N.S stands for American national standard, which is a set of guidelines and specifications that standardize pipe threads. This ensures compatibility and interchangeability between different pipe fittings and components in various industries.

The correct answer is "All of the above are correct." This means that all three statements mentioned in the question are true when referring to large refrigerant or nitrogen tanks. The protective cap must be on when the tank is not in use to prevent any leaks or accidents. Safety goggles or glasses must be worn when moving the tank to protect the eyes from any potential hazards. Additionally, large tanks should not be carried but instead secured to an approved cart for safe transportation.

Grounding wire is used in electrical circuits to protect the operator from electric shocks. It provides a pathway for the current to flow into the ground if there is a fault or short circuit in the circuit. This helps to prevent the build-up of excess voltage and ensures that the electrical system remains at a safe potential. By connecting the circuit to the ground, the grounding wire helps to divert any dangerous current away from the operator, reducing the risk of electric shock.

Brazing is a process used to join two metal pieces together by melting a filler metal and allowing it to flow into the joint. In brazing, the filler metal has a higher melting point than in soldering. Therefore, brazing is done at higher temperatures than soldering.

Pipe threads, when used on pipe that will contain liquid or vapor under pressure, need to be tapered to ensure a tight and secure seal. Additionally, they should have at least seven perfect threads to provide sufficient strength and stability. Lastly, pipe threads generally have a "V" shape to facilitate easy assembly and disassembly. Therefore, all of the above options are correct explanations for the given answer.

Flux should be used when soldering because it serves multiple purposes. Firstly, it helps prevent oxidation by creating a protective barrier between the solder and the air, preventing the formation of oxides that can weaken the solder joint. Secondly, it helps keep pipes clean by removing any dirt, grease, or other contaminants that may be present on the surfaces being soldered. Finally, flux helps solder flow easier by reducing surface tension, allowing the solder to spread evenly and create a strong bond. Therefore, all of the given statements are correct explanations for why flux should be used when soldering.

Safety glasses should always be worn when working in a machine room to protect the eyes from potential hazards such as flying debris, chemicals, or sparks. While it is true that safety glasses can fog up in certain conditions, there are anti-fog coatings available that can help prevent this issue. Additionally, there are safety glasses with ventilation systems or options for wearing anti-fog inserts to maintain clear vision. Therefore, it is important to wear safety glasses in a machine room to ensure eye protection.

When transferring refrigerants, it is important to wear goggles with side shields and gloves for safety reasons. Goggles with side shields protect the eyes from any splashes or spills that may occur during the transfer process. Gloves provide protection for the hands, preventing direct contact with the refrigerants which can be harmful. Wearing both goggles and gloves ensures that the transfer is done safely and reduces the risk of any accidents or injuries.

Aluminum ladders are conductive and can conduct electricity, making them unsafe to use around electrical equipment even if they have insulation pads on the bottoms of the rungs. Therefore, the statement is false.

To pull a vacuum means to lower the pressure in a refrigeration system below atmospheric. This is done to remove any air or moisture from the system, creating a vacuum environment. By reducing the pressure, any unwanted gases or impurities can be removed, ensuring optimal performance and efficiency of the refrigeration system.

A pressure vessel is a container designed to hold fluids or gases at a higher pressure than the surrounding environment. In this case, a cylinder containing refrigerant fits the definition of a pressure vessel as it is specifically designed to hold refrigerant under pressure. The other options do not meet the criteria of a pressure vessel as they either do not hold fluids or gases at a higher pressure or are not specifically designed for that purpose.

Fire extinguishers that can be used on any type of fire, A, B, or C, generally contain dry chemical powder to extinguish the fire. Dry chemical powder is a versatile extinguishing agent that works by interrupting the chemical reaction of the fire, smothering the flames, and preventing re-ignition. It is effective in suppressing fires involving flammable liquids, electrical equipment, and ordinary combustibles.

A compound gauge is a type of pressure gauge that can indicate pressures above 14.696 psia, pressures in inches Hg below atmospheric pressure, and is one of two gauges on a typical gauge manifold. Therefore, the correct answer is "all of the above."

When installing equipment, electrical power should always be shut off at the distribution panel and locked out in an approved manner. The distribution panel is responsible for distributing electrical power to various circuits and equipment within a building or facility. By shutting off the power at the distribution panel, it ensures that all connected circuits and equipment are de-energized, providing a safe working environment for the installation process. Locking out the panel further prevents unauthorized access or accidental re-energization, reducing the risk of electrical hazards during the installation.

Moisture in a liquid state cannot be removed with a vacuum pump directly because the pump operates by creating a low-pressure environment, which causes the liquid to boil and vaporize. Therefore, the moisture must be vaporized first before it can be effectively removed using a vacuum pump.

When soldering or brazing, the solder is melted by heat from the tubing and fitting. This is because soldering and brazing involve joining two metal surfaces by melting a filler metal, which is the solder, and allowing it to flow into the joint. The heat required to melt the solder is generated by heating the tubing and fitting, which in turn transfers the heat to the solder causing it to melt. This melted solder then solidifies to form a strong bond between the two metal surfaces.

When moisture is present in a refrigeration system, it can react with the refrigerant and the oil to form acid. This is because water can combine with certain chemicals in the refrigerant and oil to produce acidic compounds. These acids can be corrosive and can cause damage to the components of the refrigeration system, leading to decreased efficiency and potential breakdowns. Therefore, it is important to ensure that moisture is removed from the system to prevent the formation of acids.

The lowest vacuum is represented by the measurement of 1000 microns. Microns is a unit of pressure commonly used to measure vacuum levels. The higher the number of microns, the lower the vacuum level. Therefore, out of the given options, 1000 microns represents the lowest vacuum.

When joining steel pipe, pipe dope should be applied to the threads before connecting. Pipe dope is a type of sealant that is used to create a tight and leak-free connection between pipes. It is applied to the threads of the pipe to fill any gaps and prevent the pipe from leaking. This helps to ensure that the connection is secure and that there are no leaks or issues with the pipe joint.

Fires that involve electrical equipment are classified as type C fires. This is because type C fires specifically refer to fires caused by electrical equipment or wiring. These fires can be extremely dangerous as they involve the risk of electrocution and can spread rapidly if not properly handled. It is important to use appropriate fire extinguishers specifically designed for electrical fires, such as carbon dioxide or dry powder extinguishers, to effectively extinguish type C fires.

ABS (Acrylonitrile Butadiene Styrene) and PVC (Polyvinyl Chloride) pipes are not suitable for carrying refrigerants, especially in low temperature applications. These materials may not have the necessary resistance to withstand the extreme cold temperatures and the chemical properties of refrigerants. Instead, materials like copper or aluminum are commonly used for refrigerant piping due to their durability and ability to handle the temperature and pressure requirements.

The pressure inside the cylinder can be determined using the pressure-temperature relationship for R-22 refrigerant. At a temperature of 120 degrees F, the corresponding pressure is approximately 259.9 psig.

When soldering, the technician should heat the solder with a soldering iron, not a torch, to allow it to melt. Using a torch can generate excessive heat and damage the components being soldered. A soldering iron provides controlled and precise heat for melting the solder and forming a proper bond.

Fires that involve ordinary materials such as oil and gas are classified as Type B fires. This classification is based on the National Fire Protection Association (NFPA) system, which categorizes fires based on the type of fuel involved. Type B fires involve flammable liquids and gases, including oil and gas. Other types of fires include Type A (ordinary combustibles like wood and paper), Type C (electrical fires), and Type D (combustible metals).

The size indicated for the diameter of ACR copper tubing refers to the approximate outside diameter. This means that the measurement provided represents the total width of the tubing, including the thickness of the walls. The inside diameter, on the other hand, would refer to the empty space within the tubing. Therefore, the correct answer is outside diameter.

Heating the cylinder below the level of the liquid refrigerant may still create a hotspot, which can be dangerous. The torch's heat can cause the liquid refrigerant to rapidly boil and expand, leading to an increase in pressure inside the cylinder. This can potentially cause the cylinder to rupture or explode. Therefore, it is not safe to heat the cylinder in this manner.

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The molten solder slows between the two base metals being soldered because of capillary action. Capillary action is the phenomenon where a liquid flows against gravity in a narrow space, such as a small tube or gap. In this case, the solder is drawn into the gap between the base metals due to the adhesive and cohesive forces between the liquid and the solid surfaces. This allows the solder to fill in any gaps or voids, creating a strong bond between the metals.

The technician valves off the vacuum pump when evacuating to a deep vacuum within the pressure range of 500 to 300 microns. This means that the pressure inside the system should be between 500 and 300 microns for the technician to stop the evacuation process. This range ensures that the system reaches a sufficiently low pressure for optimal performance.

Sand cloth is a material that can be used for cleaning ACR copper tubing before soldering. It is abrasive and can effectively remove dirt, oxidation, and other contaminants from the surface of the tubing. This helps to ensure a clean and smooth surface, which is essential for achieving a strong and reliable solder joint. Sand cloth is commonly used in plumbing and HVAC applications for preparing copper tubing before soldering.

Noncondensable gases are undesirable in a refrigeration system because they can cause a decrease in system efficiency and performance. These gases, such as air or nitrogen, do not condense into a liquid state like the refrigerant, and instead remain in a gaseous form. This can lead to the formation of air pockets or bubbles in the system, which can hinder heat transfer and reduce the cooling capacity. Additionally, noncondensable gases can increase the pressure in the system, resulting in higher energy consumption and potential damage to the components. Therefore, it is important to remove these gases from the refrigeration system to ensure optimal operation.

The statement is false because 95/5 tin-antimony solder cannot be used in any part of a refrigeration system. This type of solder is typically used for low-temperature applications and is not suitable for use in refrigeration systems, which operate at much lower temperatures. Using this type of solder in a refrigeration system could lead to leaks or other issues.

The technician should ask for 1/2" ID Copper pipe because it is the only option that matches the required size of 5/8" ACR. The other options, 1/2" PVC and 5/8" PVC, do not match the required size.