When these refrigerants were first introduced, the chemical composition of lubricants to be used was not known. As a result, the initial testing done by Schenectady international, Inc. (SII) involved the interaction of the cured varnish films with these two refrigerants. We tested extractibles, bond strength retention and twisted pair dielectric breakdown retention after exposure to the refrigerants. No other minor insulation materials or lubricants were included as variables. A copy of the technical data sheet with our results for extractibles testing is included with this report'.

Later, we learned that polyolester and alkylbenzene lubricants were the respective lubricants of choice for R-134a and R-123. Motorettes were constructed by SII with MW35 copper conductor, ISOPOXY ® varnishes and other insulation components,, The motorettes were sent to Underwriters Laboratories, along with samples of the lubricants for testing under the UL 984 standard. The motorette and subsequent sealed tube tests were successful and SII was the first varnish supplier to obtain approval of hermetic insulation systems under UL standard 984. Copies of hermetic insulation systems SII-123 and SII-134a are also included .

With the approval of these systems and our own test data, we are confident that the ISOPOXY ® varnishes listed in the insulation systems are suitable for use in the corresponding hermetic environments. However, some of the other insulation components listed in SII-123 and SII-134a have been shown to have high extractible levels in these refrigerants. Extracted material can cause problems in the mechanics operation of a compressor. UL 984 does not address the mechanical side of the compressor system since this standard involves only electrical testing. It is, therefore, incumbent on the user of these other insulation components to determine their suitability for use in these environments.

The above are typical extraction test results we have obtained with the varnishes indicated in a number of refrigerants. Samples received two coats of varnish. Each of which was baked two hours at 325 oF. The industry guideline is for levels to be below 0.35% extractible material. Keep in mind that application procedure and cure are critical in hermetic work. Poorly cured varnish of any type may not meet this value.

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