In many cases, the contamination of recovered refrigerant is avoidable if a few best practices are followed during service and recovery.
Out of Specification
Recovered refrigerant that is determined to be out of specification generally falls into one of two categories:
• Intentional mixing of two or more different refrigerants that are not supposed to be mixed together, resulting in a product that is not close to specification.
• Predominantly one refrigerant is contaminated with some amount of another refrigerant that makes it slightly out of specification.
In the case of the first category — intentional mixing — an obvious suggestion is to avoid mixing different types of refrigerant in the same recovery cylinder.
Unintentional mixing can certainly occur when systems or previously filled recovery cylinders are not labeled correctly.
It is practically impossible to identify a single component refrigerant or refrigerant blend by pressure alone, even though a check of the pressure of a refrigerant against the PT chart will give some clue to its possible identity. For example, a container may have a pressure similar to HCFC-22, but there are several retrofit blends that may also have a similar pressure. The exception might be HFC-410A, which should actually be pretty easy to identify based on the fact that its pressure is significantly higher than other refrigerants.
If you are not sure of the identity of a refrigerant, put it into a clean, empty recovery cylinder. Do not combine an unknown refrigerant with previously recovered refrigerant that you know is not out of specification.
If a system is not labeled or reliable service records are not available to positively identify the refrigerant in question, then a sample of the refrigerant must be analyzed by a certified laboratory. Occupational Safety and Health Administration (OSHA) regulations require that containers of hazardous materials be labeled with their chemical name and Chemical Abstracts Service (CAS) number. In addition, the Department of Transportation prohibits the transportation of hazardous materials without proper identification of the contents of the cylinder as well as a green nonflammable gas label.
Since equipment owners are required to maintain records related to service or disposal of their HVACR equipment, and technicians or service companies are the source for this documentation, proper identification of cylinder contents are the key to compliance with these record keeping requirements.
In the second instance, the one dealing with cross-contamination between types of refrigerants you encounter every day, the situation can be enough to throw a recovery tank out of spec. While it would be ideal to have refrigerant-specific dedicated hoses, gauges, and recovery equipment for each of the products you handle, that may not be practical. This makes it very important to properly purge, clean, or evacuate refrigerant tools every time they are used for a different product.
Now consider another example of how easy it is to contaminate refrigerant.
An air conditioner that is charged with 6 pounds of R-22 needs only 2 ounces of another refrigerant to be swept out of a contaminated hose to put it below 98 percent. It is entirely possible that a hose or gauge set could contain this much refrigerant if not purged properly after a R-410A job or a refrigeration service call that used another refrigerant. (See Table 1.)
Editor’s Note: The material was prepared by National Refrigerants Inc. and was based on information originally published in its newsletter, National News. For more information, go to www.refrigerants.com.
Sidebar: Best Recovery and Service Practices
Here are some of the most important recovery and service best practices.
• Use dedicated recovery equipment that is separate from normal service or charging equipment.
• Purge or evacuate hoses and gauges prior to using them with a different refrigerant. Use the purge cycle on recovery machines to remove residual refrigerant contained in the machine components. Hoses with low-loss fittings or valves can contain a considerable amount of liquid refrigerant. Make sure they are safely emptied.
• Evacuate all recovery cylinders to 29 inches Hg prior to recovering refrigerant into them. Immediately label cylinders with the type of recovered refrigerant and only use the cylinders for the labeled refrigerant.
• Use a filter-drier on the inlet of the recovery machine to reduce the moisture in the refrigerant and to keep contaminants from damaging the machine.
Paying attention to best recovery and service practices that are designed to avoid contamination can save you and your customers the hassle and expense of dealing with out-of-spec refrigerant after it has been returned to a reputable EPA-certified reclaimer.
Publication date: 7/30/2012