IIAR is nearing the completion of its first standard for hydrocarbons—such as propane and butane—in large refrigeration systems. Hydrocarbons have been used for years in the petrochemical industry and are increasingly used in some refrigeration applications. Those involved in creating the initial draft said developing a hydrocarbon standard was a natural extension of IIAR’s mission to offer safe practice standards for other natural refrigerants, such as CO2 , as the refrigeration industry turns to low global-warming-potential solutions.

“IIAR has been recognized as a leader in the ammonia refrigeration industry with respect to standards development, education and advocacy, but we are expanding our outreach to natural and sustainable refrigeration in support of the Montreal Protocol and Kigali Agreement,” said Trevor Hegg, vice president of product development, industrial refrigeration and water systems, Evapco Inc.

Joe Pillis, engineering fellow, industrial refrigeration, Johnson Controls, and chairman of IIAR’s hydrocarbon task force, said global warming concerns are bringing considerable regulatory pressure to reduce the global warming potential of refrigerants used in refrigeration systems.

Hydrocarbons in refrigeration systems can help fill gaps where other refrigerants are not allowed, difficult to use, or inefficient. “Many of these gaps could be filled using hydrocarbon refrigerants,” said Charles Hon, manager, engineering, sustainability and government affairs, True Manufacturing Co. Inc. “This allows refrigerant systems to be more efficient and still not use high-GWP refrigerants or fluorinated refrigerants.”

The use of ammonia in some locations is not allowed due to the proximity to residential areas. The use of CO2 in warm climates is an issue because the energy required and reliability can be questionable. The use of the ultra-low GWP F-gases is being questioned because of cost and the decomposition by-products are under serious scrutiny. “Propane fills the gaps where ammonia and CO2 do not fit,” Hon said.

New California Air Resources Board (CARB) regulations that took effect Jan. 1 require the GWP used in cold storage warehouses and industrial process refrigeration facilities containing over 50 lbs. of refrigerant to be below 150 GWP, Pillis said. The AIM act regulations promulgated by EPA will also restrict the allowable GWP used throughout the United States. The final GWP limits by sector are still under discussion but will undoubtedly rule out most, if not all, HFC gases and blends in the near future.

HFO refrigerants can meet the GWP limit of the new rules, but they come at a cost. The new HFO refrigerants are either flammable or operate in a deep vacuum at refrigeration temperatures making systems large and expensive, Pillis said.

Additionally, there are remaining concerns that the breakdown of fluorine containing refrigerants produces polyfluoroalkyl substances (PFAS) and trifluoroacetic acid (TFA) creates several dangerous and persistent by-products. “These are likely to come under further attack once the GWP issue is addressed,” Pillis said. “Considering the issues around HFOs the only good refrigerant options left for low-temperature systems are ammonia, CO2 and hydrocarbons.”

DEVELOPING A STANDARD

IIAR has been focusing on various refrigerants, and moving into hydrocarbons has been a natural extension of the association’s work. “We know standards, and we write standards,” said Peter Jordan, senior principal engineer at MBD Risk Management Services Inc.

When Jordan first got involved with IIAR in 1991, it was 100 percent ammonia. “There wasn’t even a glint in anyone’s eyes about any other refrigerant. That has changed over the years,” he said, adding that additional guidance on hydrocarbons is needed. “The model codes address them, but in terms of a standard out there dedicated to them, we felt it didn’t exist.”

The IIAR Board of Directors commissioned a task group that first met in June of 2018 to investigate if the association should undertake a hydrocarbon refrigerant standard. The group determined there was significant interest. “A committee was assigned, and an ANSI PINS obtained to begin work on a standard shortly thereafter,” Pillis said.

The standard will follow a similar framework as the IIAR CO2 standard with sections on design, installation, startup, inspection, testing, and maintenance as well as general safety and training needs. Plus, it is a complementary standard to ammonia and CO2 . “It can be used in areas that other natural refrigerants are problematic,” Hon said. “It is very efficient and easy for trained technicians to use since handling and repairs are very similar to the high GWP refrigerants used today.”

Hegg explained that the purpose and benefit of IIAR developing these standards and other educational material is consistency. “The Standards Committee applies the same thought processes to ensuring refrigeration systems, regardless of the natural refrigerant being used, are all safe,” he said.

The committee is nearing the end of its initial draft standard, which will be reviewed by the rest of the Standards Review committee in the coming months. After that, it will be open for public review and a review by the consensus body. “I am certain there will be multiple rounds of public review, but I think we might have an approved standard by this time next year if all proceeds well,” Pillis said.

ADDRESSING SAFETY

Hydrocarbons are allowed today in self-contained systems with less than 150 grams of charge per circuit. 150 grams of propane is sufficient to produce approximately ½ ton refrigeration effect. ISO 60335-2-89 covers international requirements for use of HCs in refrigeration systems and has voted to raise the charge limit to 500 grams per circuit in self-contained units with some limitations.

“The IIAR standard will generally defer to existing limitations for those systems covered by the ISO standard,” Pillis said. “The IIAR standard is intended to address safe practice in designing and operating HC refrigeration systems above the current allowed charge limits.”

Pillis said there are many existing safety codes and standards in the U.S. that have requirements around the use of HCs in refrigeration systems. “We are working to incorporate those requirements into our standard not compete with them,” he explained.

Jordan examined model codes and their requirements for class A3 refrigerants, including the type of chemicals for these standards. “One would think they would all have the same requirements, but we don’t live in an ideal world,” he said, adding that he summarized all the requirements for the model codes and those formed, in some sense, the basis of the standard. “We try to have a harmonized standard that will allow people to comply with these codes and have practical guidance. In an ideal world, the codes would refer to us like they currently do with ammonia.”

The existing codes have fairly strict requirements, and the committee has taken a conservative approach to the hydrocarbon standard. “When we’re looking at model codes, in general, we took the requirements from the strictest,” Jordan said.

The hydrocarbon standard will feature some requirements members may not have been exposed to in the past, such as treating vapor that leaves the system. The standard also includes a separate chapter on health and safety because of the unique requirements of hydrocarbons. “This is above and beyond anything we’ve dealt with before,” Jordan said, adding that, as an example, staticsafe foot footwear and non-sparking tools are necessary. “These are the kind of precautions and requirements we want to try to make standardized through the industry.”

Hydrocarbons are very efficient, low cost and well-known natural refrigerants, but they are highly flammable. “Designing and using HC systems will require adherence to safe practices throughout the life of the HC refrigeration systems,” Pillis said. Once the standard is released, Hegg encouraged IIAR members to participate in the public review. “It will make the document better,” he said.