Low temperature coolants and refrigerants, FDA Code of Federal Regulations Title 21, PART 178
There are several challenges to low temperature extractions and processing regarding the choice of coolants and refrigerants, and many unscrupulous operators are using non approved approaches such as direct expansion/injection of non food grade liquid nitrogen into the product steam, or use of non food grade recirculating coolants. This article intends to address confusion on this issue and explain the approach taken by GPS LLC to reach high performance in a compliant and safe manner.
With respect to FDA approved approaches the relevant regulations are FDA cGMP, and more specifically Code of Federal Regulations Title 21, PART 178 which specifies which “lubricants with incidental food contact (may be safely used on machinery used for producing, manufacturing, packing, processing, preparing, treating, packaging, transporting, or holding food…” .
In the case of recirculating cooling via a glycol type coolant, typically Dynalane or similar would be used. For example Dynalene HC series offers good performance for this application, however the viscosity of HC50 greatly increases from 20.4 mPa*s @ -40 Deg C, to 38.4 mPa*s @ -50 Deg C. Such a high viscosity creates significant flow friction which reduces the cooling power of the system by requiring exponentially more pumping power as the temperature decreases further. This issue makes a cooling system configured in this manner incredibly inefficient, and requires the refrigeration system to be placed very close to the processing equipment to minimize frictional losses.
One non complaint approach used by some operators to reduce the viscosity is to use flammable non food grade coolants such as methanol or Dynalene HF-LO. This is not an acceptable or viable solution for numerous reasons.
GPS has implemented a fully compliant high performance solution using non toxic R-507 refrigerant and approved compressor lubricants. For low temperature applications GPS utilizes R-507 flooded heat exchangers – which in our two stage compressor models can chill the process solvent to -48 to -60 Deg C – and even lower temperatures (-80 Deg C) are possible with a 3-stage cascade configuration. Due to the lower viscosity of the R-507 minimal friction losses occur. R-507 is non toxic and non flammable when used with the appropriate compressor oil such as Bio-SynXtra™ Super FG which fully meets FDA 21 CFR 178.3570.
“Base oils and additives in this product are listed in 21 CFR 178.3570, Lubricants for incidental food contact (USDA H1).”
GPS utilizes ASME & CRN stamped heat exchangers featuring a seamless 316 stainless tube and shell design. Unlike in plate/frame heat exchangers used by other companies, the heat exchanger features no gaskets or seals between the process and refrigerant, only fully welded joints. This heat exchanger design can be used with ethanol, butane and many other solvents with confidence.
Regarding the refrigerants themselves NSF does not certify refrigerants, however NSF does certify ice machines, many of these ice machines use R-404A within a heat exchanger in direct contact with the ice(the heat exchanger typically forms the ice tray).
R-507 is a 50/50 mix of R-143a(1,1,1-Trifluoroethane) and R-125(Pentafluoroethane), R-404A is a pseudo-azeotropic mixed refrigerant composed of the three ingredients R-125, R-134a, and R-143a.
If R-404A is approved in such an application it is not unreasonable to construe that R-507 based on the same constituent gasses would also be acceptable in similar use cases. The FDA is unlikely in the opinion of the author to suddenly ban the use of thousands of ice and food processing machine designs based on conventional and well known technology at any point in the future.
 Current Good Manufacturing Practice (CGMP) Regulations
 CFR – Code of Federal Regulations Title 21, PART 178 — INDIRECT FOOD ADDITIVES: ADJUVANTS, PRODUCTION AIDS, AND SANITIZERS, Subpart D–Certain Adjuvants and Production Aids, Sec. 178.3570 Lubricants with incidental food contact.
 Dynalene HC Series
 Dynalene HF-LO (aliphatic hydrocarbon)
 R-507 Material Safety Data Sheet
Bio-SynXtra™ Super FG Compressor Fluids (Food Grade H1) ISO-15, 22, 32, 46, 68, 100, 150, 220
 Email w/ NSF RE: Food Grade Refrigerants 5-22-2020
 NSF Certified Ice Machine Listings
 Scotsman Ice Systems: C0530 – 500lb Cube Ice Machine Prodigy Plus Modular Cube Ice Machine Datasheet
 NSF/ANSI 12 Automatic Ice Making Equipment: Scotsman Ice Systems