An approach for flushing contaminants from oxygen breathing apparatuses for the Air Force has been adapted for the HVACR industry in dealing with burnouts and contaminated line sets.

When the Environmental Protection Agency (EPA) banned CFC refrigerants, it not only affected the HVACR industry, but many other aspects of society including the U.S. military. But one example of a non-CFC solution for the Air Force came around full circle to benefit HVACR.

After the EPA outlawed CFCs, the Air Force solicited bids for a nontoxic replacement cleaner for R-113 and R-11, which were used for flushing biological, oil, and water contaminants from onboard oxygen breathing apparatuses. Since other existing flushing agents on the market at the time didn’t clean well or were too toxic for human breathing systems, the Air Force initiated the R&D effort.

Mainstream Engineering, a Rockledge, Fla.-based research and development company with more than 70 patents and 30 current R&D projects with the U.S. military and NASA, got involved under a multimillion dollar military contract aimed at cleaning the oxygen breathing systems used in U.S. Air Force fighter jets as well as other military airplanes.

Winning a military contract is no easy task, however. Before any products are produced, the Air Force narrowed down the large field in phases to companies with the most promising theoretical concept at the best value. Eventually a Mainstream Engineering biodegradable, nontoxic flushing agent concept won out and the product was formulated. Next, the product was tested with standard chemistry analysis procedures to prove it met all the Air Force’s specifications.

To determine removal efficacy, for example, a chemist records the weight of a standard test coupon and a contaminant sample, such as refrigerant oil. After adding the oil to the test coupon and flushing it, the test coupon is weighed again to determine how much oil was left behind. Similar tests were performed for water, biological growths, and other oxygen system residuals.

Other tests involved compatibility with materials such as plastics and metals. The most critical test was related to toxicity, which requires Lethal Dose-50 and other analyses.


As it does with all products developed for NASA and the military, Mainstream Engineering launched post-contract efforts to analyze the product’s marketability for the HVACR industry. “The military and NASA are microcosms of the private sector and share many of the same technological problems,” said Dr. Robert P. Scaringe, president of Mainstream Engineering.

The product came to the HVACR market as Qwik System Flush (QSF), which is currently used as a flushing agent for general refrigeration system burnouts and contaminated line sets in HCFC-22 to HFC-410A conversions.

To prepare it for HVACR applications, Mainstream Engineering slightly reformulated the flushing agent because HVACR system burnouts and/or line set contaminants have a different ratio of water, acid, and oil than Air Force jet oxygen systems.

According to Scaringe, the industry was dealing with a rash of failed R-22 to R-410A conversions when technicians attempted reusing existing contaminated line sets because their inaccessibility within walls or under concrete slabs made replacement costs prohibitive. “At first we thought service contractors wouldn’t see value in 2-pound canisters of flushing agent at a $70 trade price, but then we realized it wasn’t expensive when considering the cost of breaking open walls or concrete slabs to replace contaminated line sets,” Scaringe recalled.


Another Mainstream product, QuikShot, also made the military-to-HVACR move. It is an acid flush that was developed under a NASA contract. Scientific challenges are associated with rejecting heat in outer space; the heat rejection causes spacecraft heat pumps to operate with a high lift that subsequently results in a high probability of acid development.

Mainstream Engineering won the NASA contract to develop an acid eliminator that accelerates the transport of acid into the filter-drier, in contrast to only neutralizing acid with a base, the latter of which could result in the formation of system-damaging salts and water residue. “If it worked in outer space, why not market it to service techs down here on earth that want to prevent acid burnouts,” Scaringe said.

Likewise, QwikCheck is an acid checker that simply attaches to a refrigeration system’s Schrader valve and samples the refrigerant for traces of acid. A presence of acid turns the QwikCheck’s yellow paper to red. The acid check was designed so that people without refrigeration backgrounds, such as astronauts or military machine operators, can check a system for acid. For refrigeration service technicians, it’s an early indicator of acid before it propagates into major system damage, said Scaringe.

Publication Date:07/06/2009