Which of the following safety precautions should be adhered to for low pressure systems? – Do not syphon refrigerant by mouth . -Avoid spilling refrigerant on the skin. -Use gloves and safety goggles when working with liquid refrigerant.
What steps should be taken to prevent air accumulation into an idle low-pressure refrigeration system?
What steps may be taken to prevent air accumulation into an idle low-pressure refrigeration system? Leave the purge unit on-line at all times. Maintain system pressure slightly above atmospheric pressure. Open the air vents on the condenser.
Why should the oil be removed from a low-pressure system at 130 degrees Fahrenheit?
When REMOVING OIL from a low pressure system, the temperature should be 130 degrees F because: LESS REFRIGERANT will be contained in the oil at the higher temperature . ... Liquid charged into a DEEP VACCUUM will boil and may lower temperatures enough to freeze water in the tubes.
What should you do after reaching the required recovery vacuum on a low-pressure appliance?
- After reaching the required recovery vacuum on a low-pressure appliance wait a few minutes to see if the system pressure rises before charging.
- When leaks in the appliance make evacuation/recovery to the prescribed level unattainable, do not proceed with the recovery.
What is the typical design burst pressure for a rupture disk on a low-pressure centrifugal air conditioning system?
| Where should the discharge from a rupture disc be piped for venting? Outdoors | What is the typical design burst pressure for a rupture disk on a low-pressure centrifugal air-conditioning system? 15 psig |
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What precaution should be taken prior to recovering refrigerant from a chiller?
Question #4: What precaution should be taken prior to recovering refrigerant from a chiller suspected of having tube leaks? Drain the watersides of the evaporator and condenser . Run the circulating pumps. Be certain the purge unit is operating.
What should be on and what should be off during a vapor removal from a low pressure refrigeration system?
During vapor removal from a low pressure refrigeration system; the system water pumps, the recovery compressor, and the recovery condenser water should all be on.
When using recovery equipment manufactured before November 15 1993 you must evacuate a low pressure chiller to what level before making a major repair?
For high- or very high-pressure appliances, the equipment must be evacuated to 0 psig before it is opened. For low-pressure appliances, the equipment must be pressurized to 0 psig before it is opened. Methods that require subsequent purging (e.g., nitrogen) cannot be used except with appliances containing R-113.
Where is the lowest access point on a low pressure centrifugal?
The lowest access point on a low pressure centrifugal air conditioning unit is the: The evaporator charging valve .
What should be done to reduce refrigerant loss from a purge unit on AR 123 chiller?
How would you SAFELY reduce refrigerant loss from a purge-unit on a low pressure unit? 1) Leak test and repair the chiller. 2) Seal the purge-unit discharge. 3) Plumb the purge-unit discharge back into the low side.
What should be used to remove ice from sight glasses?
To remove ice from sight glasses or viewing glasses, use an alcohol spray .
What method is recommended for raising the pressure of the refrigerant in a low pressure chiller?
What method is recommended for raising the pressure of the refrigerant in a low- pressure chiller? The EPA recommends circulating warm water through the chiller to raise the evaporator pressure .
What steps should be taken before using a recovery unit to remove a charge?
Question #8: What steps should be taken before using a recovery unit to remove a charge? Acid testing the refrigerant . Purging the recovery unit with nitrogen. Changing the oil in the recovery unit.
Which component is particularly susceptible to leaks in low pressure refrigeration systems with Opendrive type compressors?
The shaft seal in open-drive compressor low pressure refrigeration systems is particularly susceptible to leaks.
Which of the following is an indicator of a leak in a high pressure system with a capillary tube?
Excessive superheat is an indicator of a leak in high-pressure systems having a capillary tube.
What is the most efficient method for leak checking a charged low pressure refrigeration unit?
The most efficient method of leak checking a charged low- pressure refrigeration unit is to pressurize the system by the use of controlled hot water or heater blankets . When controlled hot water or heater blankets are not feasible, use nitrogen to increase pressure. When pressurizing a system, do not exceed 10 psig.
How is refrigerant recovery?
In vapor recovery, the refrigerant is removed an HVAC system in a vapor state . Then the vapor is condensed into a liquid by the recovery unit and, finally, transferred to the recovery cylinder. The basic process is the same as liquid recovery to a certain point.
When removing oil from a low pressure system a temperature of what must be obtained?
When removing oil from a low pressure system, the temperature should be 130 F because; Less refrigerant will be contained in the oil at the higher temperature.
When can appliances containing refrigerants be recovered?
EPA regulations require that all comfort cooling appliances (air conditioners) containing more than 50 lbs. of refrigerant MUST be repaired when the annual leak rate exceeds 15% . EPA regulations require that all Commercial and Industrial Process Refrigeration containing more than 50 lbs.
How would you remove moisture from refrigerant in a system?
Moisture can be removed from a refrigeration system by applying a vacuum . POEs hold moisture more tightly than mineral oil. But in the case of R-134a, the refrigerant effectively competes with the ester lubricant in partitioning the water (i.e., the water moves from the lubricant to the refrigerant).
How do you determine when enough vapor has entered the refrigeration system?
When the refrigerant saturation temperature increases above 32°F (freezing point of water) is the point when you know that the system has been charged with enough amount of vapor refrigerant.
When using recovery or recycling equipment manufactured after November 15th 1993 What is the required level of evacuation for a low-pressure system?
Using evacuation equipment manufactured on or after November 15, 1993; and • The compressor in the appliance is operating. should be evacuated to at least 0 psig before it is opened (if high- or very high-pressure appliance) or be pressurized to 0 psig before opening if it is a low-pressure appliance.
What are the standards for recovery equipment manufactured before November 15 1993?
(1) Equipment manufactured or imported before November 15, 1993, will be considered certified if it is capable of either recovering 80 percent of the refrigerant in the system , whether or not the compressor of the test stand is operational, or achieving a four-inch vacuum when tested using a properly calibrated ...
When using recovery equipment manufactured after 1993 it must be able to recover _% of the refrigerant when compressor is functioning?
Recovery equipment manufactured on or after November 15, 1993 must recover 90 percent of the refrigerant in the appliance when the compressor in the appliance is functioning or 80 percent of the refrigerant in the appliance when the compressor in the appliance is not functioning; or it must be able to evacuate the ...
What is the maximum safe pressure to impose on any low pressure system?
The maximum safe pressure to impose on any low pressure system is: 10 psig .
What should you do after reaching the required recovery vacuum on a low pressure appliance?
- After reaching the required recovery vacuum on a low-pressure appliance wait a few minutes to see if the system pressure rises before charging.
- When leaks in the appliance make evacuation/recovery to the prescribed level unattainable, do not proceed with the recovery.
What steps can be taken to prevent air accumulation into an idle low pressure refrigeration system?
What steps may be taken to prevent air accumulation into an idle low-pressure refrigeration system? Leave the purge unit on-line at all times. Maintain system pressure slightly above atmospheric pressure. Open the air vents on the condenser.
Why do chillers require purge units?
Both CFC-11 and HCFC-123 chillers require purge units because : leaks in the appliance make evacuation to the prescribed level unattainable . ... Where does refrigerant go after it leaves the purge unit of a low pressure centrifugal system?
What should be on and what should be off during a vapor removal from a low pressure refrigeration system?
During vapor removal from a low pressure refrigeration system; the system water pumps, the recovery compressor, and the recovery condenser water should all be on.
Where is the rupture disc located on centrifugal chiller?
| Where should the discharge from a rupture disc be piped for venting? Outdoors | Where is the rupture disc located on a centrifugal chiller? Evaporator | A hydrostatic tube test kit will; Determine if a tube leaks. |
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What precautions should be taken prior to recovering refrigerant from a chiller suspected of having tube leaks?
Question #4: What precaution should be taken prior to recovering refrigerant from a chiller suspected of having tube leaks? Drain the watersides of the evaporator and condenser. Run the circulating pumps . Be certain the purge unit is operating.
Which recovery equipment maintenance practices should be performed on a regular basis?
According to the EPA, which recovery equipment maintenance practice(s) should be performed on a regular basis? Check recovery device for refrigerant leaks .
Where is the lowest access point on a low pressure centrifugal?
The lowest access point on a low pressure centrifugal air conditioning unit is the: The evaporator charging valve .
Where is refrigerant added to a low pressure system during the charging process?
Where is refrigerant added to a low-pressure system during the charging process? The lowest access point on the system such as the evaporator charging valve .
Which of the following refrigerants should be used in a low pressure appliance?
Type 3 refrigerants are called low-pressure refrigerants as they are used in low-pressure appliances. Type 3 refrigerants include: R-11 (CFC) R-123 (HCFC)
What should be done to reduce refrigerant loss?
How would you SAFELY reduce refrigerant loss from a purge-unit on a low pressure unit? 1) Leak test and repair the chiller . 2) Seal the purge-unit discharge. 3) Plumb the purge-unit discharge back into the low side.
Which component is particularly susceptible to leaks in low-pressure refrigeration?
The shaft seal in open-drive compressor low pressure refrigeration systems is particularly susceptible to leaks.
Where do leaks commonly occur in low-pressure systems?
On this side of the system, the refrigerant is a cold, low-pressure liquid. The refrigerant line on the system’s low side is often known as the suction line because the compressor’s action pulls refrigerant towards it. Leaks on the suction side most commonly occur in the evaporator coil or one of the fittings .
