Recycled R-134a refrigerant cannot exceed what levels of contaminants?
A) Moisture: 50 PPM by weight
B) Refrigerant oil: 500 PPM by weight
C) Non-condensable gases (air): 150 PPM by weight
D) all the above
When external portable containers are used for transfer of recycled refrigerant, they must be evacuated to at least __, before being put into service.
A) 2 in Hg
B) 10 in Hg
C) 17 in Hg
D) 27 in Hg
The Correct Answer and Explanation is:
Let’s break down each part of your question carefully.
Question 1: Contaminant Limits in Recycled R-134a Refrigerant
Options:
A) Moisture: 50 PPM by weight
B) Refrigerant oil: 500 PPM by weight
C) Non-condensable gases (air): 150 PPM by weight
D) All the above
Correct answer: D) all the above
Explanation:
R-134a is a commonly used refrigerant, especially in automotive air conditioning and refrigeration systems. When refrigerants are recycled, it’s critical to control contamination levels to ensure the system’s efficiency, safety, and longevity. Contaminants such as moisture, oil, and non-condensable gases can severely impact the refrigeration cycle and equipment operation.
- Moisture (Water Vapor):
Moisture in refrigerants can lead to the formation of acids and corrosion inside the system. It also causes ice formation in expansion valves or capillary tubes, leading to blockages. For recycled R-134a refrigerant, moisture levels must not exceed 50 parts per million (PPM) by weight to avoid these problems. - Refrigerant Oil:
Oil contamination beyond acceptable levels can cause lubrication issues and reduced heat transfer efficiency. While oil is necessary for compressor lubrication, excess oil in the refrigerant can impair system performance, cause clogging, and reduce heat exchange efficiency. The maximum allowable limit for refrigerant oil in recycled R-134a is 500 PPM by weight. - Non-condensable Gases (Primarily Air):
Air and other non-condensable gases trapped in the refrigerant can cause higher operating pressures and reduced cooling capacity. These gases do not condense and remain in the system, causing increased pressure, corrosion, and inefficient operation. The maximum allowable non-condensable gases in recycled refrigerant is 150 PPM by weight.
Because all these contaminant limits are critical and specified, option D) all the above is correct.
Question 2: Evacuation Level for External Portable Containers Used in Refrigerant Transfer
Options:
A) 2 in Hg
B) 10 in Hg
C) 17 in Hg
D) 27 in Hg
Correct answer: D) 27 in Hg
Explanation:
When using external portable containers to transfer recycled refrigerant, it is essential to evacuate these containers to remove air and moisture before filling them with refrigerant. The evacuation process ensures that the container has minimal contamination, preventing the introduction of air, moisture, or other impurities into the refrigeration system.
- Evacuation level is measured in inches of mercury (in Hg) vacuum pressure, which quantifies how much air and moisture are removed.
- A vacuum level of 27 in Hg corresponds to a deep vacuum—close to the maximum achievable by typical refrigeration vacuum pumps—meaning most non-condensable gases and moisture are effectively removed.
Evacuating to 27 in Hg ensures that the container is as free of contaminants as possible before refrigerant transfer, maintaining system integrity and performance.
Summary
- Recycled R-134a refrigerant must have contamination levels below:
- Moisture: 50 PPM
- Oil: 500 PPM
- Non-condensable gases: 150 PPM
- External portable containers must be evacuated to at least 27 in Hg vacuum before use to ensure they are free from contaminants.
Both practices are crucial to maintaining the performance, reliability, and safety of refrigeration systems using recycled refrigerant