Most HVACR technicians will need to raise their levels of safety consciousness when servicing equipment using flammable hydrocarbon (HC) refrigerants, such as R-290 (propane) or R-600a (isobutane), and the first place many technicians are likely to encounter these HCs will be in smaller kitchen equipment, such as reach-in coolers.
That’s the word from Art Miller, principal of KAM Associates, a firm that provides educational training for the HVACR industry. He also serves as the Region 2 director for the Refrigeration Service Engineers Society (RSES).
Miller said technicians will need to follow a slightly different routine after identifying that a piece of equipment they’ll be working on uses an HC.
According to Miller, the changes will start with the preparation. Before beginning work on an HC system, technicians must:
- Make sure the area is adequately ventilated and provide additional ventilation if necessary;
- Have a fire extinguisher available; and
- Have a flammable gas detector turned on before they enter the space, keep it turned on during the process, and only turn it off after they leave.
In addition, technicians must be aware that tubing cutters, not torches, are the preferred disassembly method for systems containing an HC. Similarly, technicians will need to be especially cautious and diligent when using a torch to ‘seal’ process tube ends. Purging the system with nitrogen will be essential to ensure no HCs remain in the system.
Venting and transportation of HCs also will require new ways of thinking.
“Technicians have the option of venting HCs,” Miller said. “So they will need to know how to do that safely or how to recover the refrigerant safely. If technicians recover the HC, transporting it may become an issue. The vehicle will need to be ventilated and may possibly require a flammable materials placard.”
For R-600a systems, technicians will need to be aware that the low-side pressure during operation will be in a vacuum. Technicians must be very careful not to introduce air into the system under these conditions.
“Air in HC systems raises the head pressure and introduces moisture, which create acids,” Miller noted. “It‘s very destructive to the system.”
In addition, technicians may not be used to pulling vacuums as low as those recommended by the manufacturers of HC equipment. Miller said he is hearing from manufacturers of low-temperature refrigeration equipment that technicians should be pulling a vacuum of 200 microns, and most guys are not used to thinking that low.
Despite these changes, Miller does not expect there to be a huge learning curve when it comes to working with HC refrigerants, especially given all the changes the HVACR industry and its technicians have endured in the recent past.
“After a few service calls with this equipment, they start to get into the routine,” he said. “I need ventilation, a gas detector, and a fire extinguisher. It shouldn’t take them long to figure it out. The good news is the pressures and temperatures for HCs are very similar to R-134a. We’re not seeing excessively high back pressures like we did with R-410A, which was a much tougher learning curve for techs.”
A HIGH-PURITY PRODUCT
Brad Dunn, business development at industrial gas supplier Cee Kay Supply, added that as most technicians may be aware, R-290 is a high-purity refrigerant and is not interchangeable with standard industrial-grade propane.
“R-290 is a 99.5 percent pure propane that has been treated to remove moisture and is certified by UL to be used in refrigeration applications,” he said. “Any moisture that gets into an HC system really wreaks havoc, and there is some propane of questionable purity on the market. So, make sure to buy from a reputable supplier with products carrying the UL certification stamp.”
Also, unlike the propane you use with your backyard barbecue, which is treated with the odorant mercaptan, R-290 is odorless.
“With R-290 products, you would not be able to notice a leak without a combustible gas detector,” Dunn said. “That’s why it’s imperative to have a gas leak detector when working on any type of R-290 system.”
In addition, technicians must be aware that traditional refrigeration compressors cannot be retrofitted to be made compatible with R-290. Compressors must come from the manufacturer designed with R-290-approved components.
“No retrofitting that I have seen out there can be done safely,” Dunn said. “All of the R-290 parts need to be sealed, which means no wire nuts and no crimp connectors. Electrical components need to be sealed for use with R-290, so there’s no risk of electrical ignition. If you‘re putting in an aftermarket part, such as a fan motor, you need to make sure all parts are approved for use in an R-290 system.”
Finally, simply being cognizant of one’s surroundings is good advice when working with HC refrigerants.
“Make sure you’re in a well-ventilated area, and if you’re venting an HC to the atmosphere, check first to ensure there are no ignition sources around,” Dunn said.
A CONTRACTOR’S TIPS
From a contractor’s perspective, Frank Bacchetta, chief business officer, Total Comfort Group, Iselin, New Jersey, offered these safety precautions for working on systems that use R-290:
- Post a sign in plain sight that states “Danger: flammable gas. No smoking, matches, or open flames;
- Always carry a leak detector that is capable of sniffing propane. This is to be used and left on in the working area while performing work on the system;
- Purge the system before brazing. Use oxygen-free dry nitrogen, set at 3-5 psig, for at least two minutes prior to brazing;
- R-290 can be released into the atmosphere, but before doing so, cone off your area and verify no smoking, sparks, or flames are present. While venting the R-290, your gas detector should be alerting. Once the gas has been released and the detector has stopped alerting for at least two minutes, it is safe to continue work.
Bacchetta also shared some resources that he and the technicians at Total Comfort Group have found useful:
THE IMPORTANCE OF TRAINING
RSES will be releasing the third edition of its HC manual later this summer. RSES also offers training through its online e-learning portal. Technicians who finish the training receive a certificate of completion.
“The EPA [U.S. Environmental Protection Agency] does not require certification to work with HCs, but the EPA does recommend technicians receive training on servicing equipment containing HCs,” Miller said. “If I were a contractor, I’d certainly want my technicians to participate in HC training to at least show on paper that every effort was made to ensure they were instructed on how to do it right.”
For additional information and training on HCs, visit www.rses.org.
Publication date: 7/10/2017