Questions Re: Scope of UL 1203/FM 3615 Chemical Compatibility Test

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jhm5016

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I am tasked with designing a flameproof wire bushing to allow 25 wires to pass from a flameproof compartment to a non-flameproof compartment. Our certifier is using standard UL 1203 to evaluate this design for US certification. I have been told that the chemical compatibility test of UL 1203 (Cl. 33.3) will need to be performed on a bushing sample with the wires. I have found a few sealants that are advertised as suitable but I can not find any information on wire insulation types (e.g- PVC, ETFE, XLPE) that are known to pass this chemical test.

My search for UL 1203 compatible sealants and wires has created a lot of confusion. Perhaps nothing exemplifies my confusion better than the widely-available flameproof solid conduit fittings which use cement-based sealants. My research is suggesting that these cement-based sealants are not subject to chemical resistance testing. Furthermore, I do not see any specific limitations for wire types that are to be used with these flameproof conduit fittings. This would seem to suggest that chemical resistance is not an issue.

We have also spoken with a company that specializes in flameproof wire bushings and they have indicated that only their sealant was chemical tested and that the wires were never considered by their certification agency. This only adds to the confusion.

I am wondering now if our certifier is applying this test correctly. Things are not adding up. Has anyone here had experiences certifying a flameproof wire bushing? Any assistance with making sense of this chemical test would be greatly appreciated.
 
Are you sure this is a flameproof application rather than explosionproof? They are tested to different standards. See the FPN/IN for their respective definitions in Sections 500.2 and 505.2. Once that has been clarified the sealing bushing issue can be discussed more intelligently.
 
rbalex said:
Are you sure this is a flameproof application rather than explosionproof? They are tested to different standards. See the FPN/IN for their respective definitions in Sections 500.2 and 505.2. Once that has been clarified the sealing bushing issue can be discussed more intelligently.
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Bob-
Thank you for the quick reply. I have been searching around this forum and I appreciate how thorough you are in all of your responses. What I mean to say here is explosion-proof because we need to certify to the "Division" rating system described within NEC Section 500.
 
It appears the confusion is caused by attempting to "mix and match" Division and Zone (especially IEC/CENELEC/ATEX) concepts. Flameproof wire bushings are a "Zone" concept.

That said, you could simply purchase them from a suitable manufacturer. Or, if you chose to manufacture your own, you can use any sealant you believe to be suitable since they are testing/certifying the entire assembly, assuming your certifier is a Nationally Recognized Testing Laboratory [NRTL]. If it passes, you're home free.

Most common conductors will have no problem with the chemical compatibility tests.

However, as I mentioned before explosionproof and flameproof have different test standards and many, although certainly not all, flameproof seals have difficulty passing the explosionproof tests.
 
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Bob- thanks again for your feedback. Unfortunately, my research is not yielding very many options. Finding a "suitable sealant" is really the issue here. I am having issues finding a sealant that is known to pass the for all 13-chemicals of the UL 1203 test. As far as I can tell there is not a single sealing product that is advertised to pass for all 13 chemicals. This is putting us in an undesirable position where we will have to use an unproven sealant with our design and incur the additional certification costs that go along with using an uncertified component. It seems very odd to me that (a) there exists no UL 1203-recognized sealants (the ones that I have found have failed for at least 1 of the 13 chemicals in the test) and (b) that cement-based sealants are not required to undergo this test (according to our certifier, and as inferred from my research). Unfortunately we cannot use a cement-based sealant for other reasons.
 
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