Podcast
Questions and Answers
Why could a recycling or recovery machine that uses a hermetic compressor overheat when drawing deep vacuums?
Why could a recycling or recovery machine that uses a hermetic compressor overheat when drawing deep vacuums?
The motor relies on the flow of refrigerant through the compressor for cooling
Starting in 2019, what leak rate triggers the EPA requirement that commercial refrigeration systems containing 50 pounds or more of R-22 be repaired?
Starting in 2019, what leak rate triggers the EPA requirement that commercial refrigeration systems containing 50 pounds or more of R-22 be repaired?
20%
When could a reciprocating compressor be damaged if energized?
When could a reciprocating compressor be damaged if energized?
When the discharge service valve is closed.
Recovering refrigerant from a system in the vapor phase will minimize the loss of which of the following?
Recovering refrigerant from a system in the vapor phase will minimize the loss of which of the following?
When recovery is first started, at what phase is the refrigerant removed to save recovery time?
When recovery is first started, at what phase is the refrigerant removed to save recovery time?
Before making a major repair, technicians must evacuate an appliance or component containing more than 200 pounds of R-410A to which of the following levels?
Before making a major repair, technicians must evacuate an appliance or component containing more than 200 pounds of R-410A to which of the following levels?
After a leak repair of a supermarket using 3000 pounds of R-22 and a successful initial verification test, when must a follow-up leak verification test be conducted?
After a leak repair of a supermarket using 3000 pounds of R-22 and a successful initial verification test, when must a follow-up leak verification test be conducted?
Which of the following refrigerants would be used in a low-pressure appliance?
Which of the following refrigerants would be used in a low-pressure appliance?
What should be done if an initial leak verification test failed after repairing a leak in a rack refrigeration system for a supermarket using an HCFC refrigerant?
What should be done if an initial leak verification test failed after repairing a leak in a rack refrigeration system for a supermarket using an HCFC refrigerant?
Where must you connect a hose in order to recover liquid refrigerant?
Where must you connect a hose in order to recover liquid refrigerant?
Which of the following is an indicator of a leak in a high-pressure system with a capillary tube?
Which of the following is an indicator of a leak in a high-pressure system with a capillary tube?
Recovered refrigerant may contain which of the following impurities?
Recovered refrigerant may contain which of the following impurities?
You are changing out the compressor of a system containing 40 pounds of R-404A. In addition to isolating the compressor, which of the following procedures should you follow?
You are changing out the compressor of a system containing 40 pounds of R-404A. In addition to isolating the compressor, which of the following procedures should you follow?
For what refrigerant is an equipment room refrigerant detector NOT required under ASHRAE Standard 15 provided the mechanical ventilation system in the machinery is run continuously?
For what refrigerant is an equipment room refrigerant detector NOT required under ASHRAE Standard 15 provided the mechanical ventilation system in the machinery is run continuously?
Your recovery/recycling machine has R-22 refrigerant in it. You now have to recover refrigerant from an R-410A unit. What must be done before recovery?
Your recovery/recycling machine has R-22 refrigerant in it. You now have to recover refrigerant from an R-410A unit. What must be done before recovery?
Which is the easiest way to check the type of refrigerant used in a 60-ton packaged rooftop unit?
Which is the easiest way to check the type of refrigerant used in a 60-ton packaged rooftop unit?
Refrigerant has been recovered from an air-conditioning system and held in a refillable cylinder in order to replace the condenser coil. What can be done with the refrigerant?
Refrigerant has been recovered from an air-conditioning system and held in a refillable cylinder in order to replace the condenser coil. What can be done with the refrigerant?
It is best practice to use dry nitrogen to break the vacuum when dehydrating by the triple evacuation method. However, what is required?
It is best practice to use dry nitrogen to break the vacuum when dehydrating by the triple evacuation method. However, what is required?
What is the state of the refrigerant leaving the receiver in a refrigeration system?
What is the state of the refrigerant leaving the receiver in a refrigeration system?
Why do gauge set hoses used for field service work have self-sealing connectors or hand valves?
Why do gauge set hoses used for field service work have self-sealing connectors or hand valves?
When first inspecting a hermetic system known to be leaking, what should you look for?
When first inspecting a hermetic system known to be leaking, what should you look for?
Which of the following CANNOT be used as a reason to extend the appliance repair deadlines?
Which of the following CANNOT be used as a reason to extend the appliance repair deadlines?
How would you remove moisture from refrigerant in a system?
How would you remove moisture from refrigerant in a system?
Which of the following statements about recycling and recovery equipment used for stationary refrigeration is FALSE?
Which of the following statements about recycling and recovery equipment used for stationary refrigeration is FALSE?
When is it against EPA regulations to use system-dependent recovery equipment?
When is it against EPA regulations to use system-dependent recovery equipment?
How can you speed up the removal of the refrigerant charge from a system?
How can you speed up the removal of the refrigerant charge from a system?
Which part of a belt-driven non-hermetic compressor is most likely to leak if the compressor has not been used for several months?
Which part of a belt-driven non-hermetic compressor is most likely to leak if the compressor has not been used for several months?
A comfort-cooling appliance containing 50 pounds or more of R-22 is found to be leaking beyond the appliance leak rate threshold. How many days do you have to repair the leak and conduct the initial leak verification test?
A comfort-cooling appliance containing 50 pounds or more of R-22 is found to be leaking beyond the appliance leak rate threshold. How many days do you have to repair the leak and conduct the initial leak verification test?
When can appliances containing refrigerants be recovered to atmospheric pressure?
When can appliances containing refrigerants be recovered to atmospheric pressure?
Identify the best method to charge a system that has both an air-cooled condenser and evaporator with a nameplate charge of 80 pounds.
Identify the best method to charge a system that has both an air-cooled condenser and evaporator with a nameplate charge of 80 pounds.
What is the primary water source for a water-cooled recovery unit's condensing coil?
What is the primary water source for a water-cooled recovery unit's condensing coil?
After refrigerant liquid has been recovered from the appliance, what is done with any remaining vapor?
After refrigerant liquid has been recovered from the appliance, what is done with any remaining vapor?
Every refrigerating system must be protected by which of the following?
Every refrigerating system must be protected by which of the following?
When should refrigerant be removed from the condenser outlet?
When should refrigerant be removed from the condenser outlet?
Which of the following should be replaced if a system is opened for servicing?
Which of the following should be replaced if a system is opened for servicing?
What steps should be taken before using a recovery unit to remove a charge?
What steps should be taken before using a recovery unit to remove a charge?
What should be done after reaching the required recovery vacuum on an appliance?
What should be done after reaching the required recovery vacuum on an appliance?
When a trace gas becomes absolutely necessary, which of the available gases should be used to help locate a leak?
When a trace gas becomes absolutely necessary, which of the available gases should be used to help locate a leak?
Pressure relief valves can only be installed in which configuration?
Pressure relief valves can only be installed in which configuration?
What should be done before transferring refrigerant to an empty cylinder?
What should be done before transferring refrigerant to an empty cylinder?
Which of the following repairs would always be considered 'major' under EPA's regulations?
Which of the following repairs would always be considered 'major' under EPA's regulations?
Every refrigerating system must be protected by which of the following?
Every refrigerating system must be protected by which of the following?
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Study Notes
Refrigerant Management
- Hermetic compressors require refrigerant flow for cooling; overheating occurs during deep vacuum draws.
- Starting in 2019, EPA mandates repairs for commercial refrigeration systems with R-22 if leak rates exceed 20%.
- Recovering refrigerant in vapor phase minimizes oil loss, while liquid phase recovery initially saves time.
Leak Detection and Repair Protocols
- Appliances with over 200 pounds of R-410A must be evacuated to 10 inches of Hg vacuum before major repairs.
- Follow-up leak verification tests must be conducted within 10 days after successfully repairing leaks in systems containing R-22.
- Excessive superheat indicates potential leaks in high-pressure systems with capillary tubes.
Equipment and Maintenance Procedures
- Use R-123 for low-pressure appliances and verify refrigerant type by checking the unit nameplate.
- If a recovery unit contains R-22, remove it and change the filter before recovering R-410A.
- An appliance containing 50 pounds or more of R-22 with leak rates beyond the threshold must be repaired within 30 days.
Recovery and Recycling Processes
- For systems not designed with a pressurized recovery system, the recovery process must adhere to EPA regulations.
- Check service valve positions and recovery oil levels before utilizing a recovery unit.
- Use dry nitrogen with a pressure regulator for effective dehydration in triple evacuation methods.
Environmental and Safety Compliance
- Refrigeration systems must have a pressure relief device for safety compliance.
- It is against EPA regulations to use system-dependent recovery equipment for appliances with over 15 pounds of refrigerant.
- Identifying the requirement for a major repair, such as replacing an evaporator coil, is essential for compliance.
Refrigeration System Operation
- Refrigerant is in high-pressure liquid state when leaving the receiver in refrigeration systems.
- Cooling the recovery cylinder can expedite refrigerant removal from systems.
- After achieving the required recovery vacuum, monitor the system pressure for stability.
Additional Considerations
- Traces of oil are key indicators of leaks in hermetic systems.
- A filter drier should be replaced every time a system is opened for servicing to ensure system efficiency and safety.
- The proper method to charge systems with both air-cooled condenser and evaporator is through the liquid-line service valve.
Leak Locating Techniques
- Use nitrogen mixed with a trace of system refrigerant gas to detect leaks when necessary.
- Any remaining refrigerant vapor in the system is extracted by the recovery system after liquid recovery.
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