Experimental evaluation of flame-free refrigerant fittings according test criteria specific to R744.

The successful use of CO2 as a refrigerant on a large scale and its introduction to new applications requires the development of system components, including reliable, low-cost refrigeration fittings. Press fittings are an attractive option, because this connection type does not require an open flame, is easy to establish, and is suitable for field maintenance. However, the use of R744 exposes this fitting type to challenges that are characteristic to CO2 only. This paper reports the research conducted to explore the suitability of this new fitting type for use with CO2, including new test methods to study explosive decompression characteristics of its O-ring materials and the ability of the fittings’ stainless steel body to withstand exposure to carbonic and activated acids. The results show that the sealing ability of the tested fittings is not compromised by explosive decompression or exposure to carbonic and activated acids.