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Cooper flare joints have been used in small units of all types for decades. They are easily constructed and dismantled in the field, but so are other types of mechanical fittings.

But why did the small commercial and domestic refrigeration and air conditioner industry adopt on this type of joint in the first place in preference to other types of joint?

My own theory, for what it’s worth, is that the small refrigerator industry, extending from small commercial devices into homes as domestic fridges originated in the US during the 1920’s, dominated, it would seem, by a number of large manufacturers, prominently Frigidaire.
Prior to the use of CFC in the early 30s the main refrigerants in use were Ammonia and Sulphur Dioxide. The former had to use steel pipes, the latter could use copper.
Frigidaire was instrumental, with DuPont, in developing CFCs commercially for refrigerant use and was, I believe, at the time a division of General Motors.

Did the flare type joint stray into refrigeration territory from the motor car industry, where a similar joint was used in hydraulic and brake systems?

Has anybody got any ideas?


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