Steve Brown, trainer, Educational Services, Emerson Climate Technologies, pointed out the similarities between R-22 and R-410A during the period when 22 was being phased out, and 410A was moving in.
According to HVACR historian Bernard Nagengast, R-22 was introduced in 1936. However, “it was little used until after WWII.” Its first use was in industrial and large commercial low-temperature refrigeration systems.
“In the 1950s it was used in household freezers with hermetic compressors,” he said. “However, that use was short lived due to high compressor failure rates (due to high discharge temperatures when used at high compression ratios - high discharge temps kill off hermetic compressors fast).”
The first use of R-22 in air conditioning was in the later 1950s, mainly as a replacement for R-12 because it permitted the use of smaller compressors and piping. “Yes, there was some fear in the service area about the higher pressures,” Nagengast said. “I heard that from an old-time service manager when I was doing some of that work.”
According to Steve Brown, trainer, Educational Services, Emerson Climate Technologies, the same fears were expressed during the period when 22 was being phased out, and 410A was moving in (roughly 2001).
“We have provided training primarily on Copeland compressors since the late 1940s and have been addressing the EPA refrigerant issues since the mid 1980s,” Brown said. “As the EPA Refrigerant Handling Guidelines evolved in the 1990s, we incorporated that training into our classes with emphasis on retrofitting from CFC refrigerants to HCFC refrigerants, and have continued that practice into all of our current training programs.”
R-410A TRAINING
Several years ago, Brown told his refrigerant-handling classes about what happened when R-22 was just becoming popular for air conditioning.“The service mechanics of those days were comparing the pressure difference between R-12 and the higher pressure of R-22, and were concerned about the higher pressures with regard to handling systems with the higher pressure R-22. I stated that we have history repeating itself with the transition from R-22 to R-410A, as some service mechanics, especially the older ones, were saying that they didn’t want anything to do with the new R-410A because of its much higher pressures” - 60-70 percent higher than R-22.
Primary replacements for HCFCs in installed systems include R-507, -404A, and -134a, all of which use POE oils. For technicians, that replacement job includes flushing the system to clear it of all mineral oil.
Dave Metcalf, marketing manager, Honeywell, spoke to refrigerant technicians at the Garden State-RSES (Refrigeration Service Engineers Society) Service Seminar held in Morristown, N.J., at Honeywell’s world headquarters in 2001.
R-410A had arrived; at the time there were more than 250,000 systems with R-410A, Metcalf pointed out, so contractors and technicians needed to learn how to service them. However, he said there was still “misinformation and confusion” among air conditioning contractors concerning this refrigerant and those he mentioned as replacements.
“R-410A is already used in new unitary equipment,” Metcalf said at the time. “R-407C is being used in Europe, but it’s less efficient than 410A.” R-410A is 5 percent more efficient than 22, he said, and 10 percent more efficient than 407C and 134a. These higher pressures allow for more compact design, with smaller scrolls and rotors.
As for safety, “High pressures are not that dangerous,” he said. “It’s good to ask questions at first. [R-410A’s] pressure jump is the same as from 12 to 22,” a 65-75 percent pressure increase.
Manufacturers did stress the importance of only using new gauges appropriate to the new refrigerant, since using the old ones could blow apart under that increased pressure. This could lead to freeze-burns and injury from flying metal.
Service practices changed in response to the new refrigerant, to prevent the incursion of moisture and noncondensibles into the system. The advice included:
• Upon installing or servicing a unit with polyolester (POE) oil, make sure that a new R-410A-compatible filter-drier is installed anytime the system is opened.
• Remember, a vacuum alone will not remove moisture.
• Brazed-in or sweat-style filter-driers must be cut out of the system, to avoid recontamination.
• Never start a compressor under a system vacuum.
“As time moves on, OEMs have been marketing new a/c systems with R-410A, some of the old-timers have retired, and ultimately, service mechanics have taken the EPA Refrigerant Handling Guidelines in stride,” said Brown.
“Most of the older equipment has been replaced with new and better designed systems offering higher EER ratings,” he said.
“Service people across the country are better educated about refrigerants and through the efforts of Emerson Educational Services, our in-warranty compressor returns have dropped dramatically.”
Publication date:06/27/2011
Report Abusive Comment