Sealed external connector recommendations - Page 1
Forum section: electronics / projects

author: tooki
author_rank: Super Contributor
timestamp: December 02, 2023, 07:29:31 pm
content: I need to build a control cabinet for a chemical synthesis system, to power and control pumps, valves, heaters, an autosampler, and liquid chromatography gear. (Luckily I don’t have to do any of the actual control programming myself!) In essence, it needs AC power and USB to go in, and AC power, DC power, and various control signals to the gear. The cabinet itself will be mounted inside the fume hood together with the gear it’s controlling.Because the solvent used in this synthesis, dimethylformamide (DMF) is extremely aggressive to most plastics, I need to keep it and its vapors out of the cabinet. The plan is to also use positive pressure (either air or nitrogen) to prevent ingress, since DMF vapors caused problems in earlier setups. It’s also the plan to put the connector bank behind a splash guard. All the wires will be either Teflon-insulated or put inside Teflon tubing to protect them from DMF splashes.Anyhow, I’m after some suggestions for connectors to use for the heaters in particular. They’re 230V cartridge heaters, 14 of them in total. I simply don’t have the space to give each one its own C13/C15/C15A connector, and unfortunately most of the denser connectors I’ve found (e.g. sealed D-sub) aren’t rated for 230V. For the heaters (and the PT100 temperature sensors) I’d be happy to have cable clamp terminal blocks, but I can’t find any sealed panel-mount female ones. (Pluggable terminal blocks would be even better, but they all use male headers, which I don’t consider safe for 230V.) M8 industrial sensor connectors aren’t rated for 230V.Nonnegotiable requirements:- safe to touch when energized, so no exposed contacts- rated for 230V (current is small, under 350mA)- compact (max 200mmReeeeally want, but negotiable:- sealed (if not, then something I can seal from the back with silicone or something)- ability to disconnect heaters individually, either by each having its own connector, or by the mating plug allowing reasonably quick replacement of a pair of pins (like how crimped d-sub and military circular plugs let you quickly pop out contacts).- orderable from Digikey, RS, Distrelec, Conrad, or Compona. (Since I am still fighting with Mouser and Farnell to get accounts set up)Nice to have but low priority:- crimp or cable clamp (not solder) terminationI have been considering things like circular connectors (like Amphenol Ecomate, which I will likely use for other things on this cabinet) and circular DIN connectors, M12 sensor connectors, a bunch of individual 2mm safety banana jacks, or even something like Molex Micro-Fit which I’d have to seal myself. I could even put terminal blocks on a PCB and use that as a panel, I suppose.Any thoughts? Anything else I should be looking at?Thank you!

author: jonpaul
author_rank: Super Contributor
timestamp: December 02, 2023, 07:39:38 pm
content: We used similar on cinema lighting equipment for outdoor use at 280V 200A.Check the Mine and chemical grade connectors from Europe mfg.Expect special order and high cost, dely time.Bon chancej

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: December 03, 2023, 05:32:47 am
content: There are several (mainly US based) companies which manufacture hermetically sealed derivates of most MIL connector series. On those, you have no plastics at all, as they are made with metal-to-glass insulation. But the contacts are not removable. And only a few can be found via the usual (QPL/QPD) way. I have links for several, but I am not sure when I will get around to look for them, because there is a major upheaval at my workplace going on.

author: CosteC
author_rank: Regular Contributor
timestamp: December 03, 2023, 02:49:25 pm
content: How about Wurth Elektronik M12 connectors? Low pin number flavours have 250 V rating.Exists in metal and plastic flavours.Full chemical resistance requirement will probably move price to absolutely horrible levels.

author: ConKbot
author_rank: Super Contributor
timestamp: December 05, 2023, 08:43:31 am
content: If you can provide your own chemical protection, neutrik "powercon true 1 top" seems in the right direction. Sealed, latching, fits in an xlr panel knockout, so a mild improvement over c13 space wise. Touch and voltage stuff taken care of. Now had load breaking capacity the earlier versions didn't.Might not be dense enough for you though.

author: Terry Bites
author_rank: Super Contributor
timestamp: December 05, 2023, 08:59:39 am
content: I have a penchant for Bulgin connectors.www.bulgin.comTheir website is crap, but dont be put off. Try mouser or farnell for listings.I've had bad experiencies with Neutrik, a real faff to assemble correctly and they aint all that water proof.You really need to contact the makers of ip rated connectors to check on compatibilty.https://jehbco.com.au/products/chemical-compatibility-chart/Mobile drug labs are never easy.

author: coppercone2
author_rank: Super Contributor
timestamp: December 05, 2023, 09:40:42 am
content: it needs to be rated for the chemical because making it all fancy might eventually lead to brittle insulation that flakes off like dry pasta and creates some crazy problem not seen by simple point to point wiring in a electrical box with ugly connectors, the old stirrers I serviced had some crazy shit going on with wires (from a corrosives lab)still working though even thought it was basically knob and wire at that point. there would probobly be a hilarious electrical event if there was some high density fancy pants sealed connector in there that started to decay

author: tooki
author_rank: Super Contributor
timestamp: December 06, 2023, 07:55:24 am
content: Thanks for the replies, everyone.So what I ended up deciding on is to use small hose fittings (customized by the machinists) to run Teflon hoses as conduit with the wires within (terminated at internal terminal blocks); with the positive pressure in the cabinet, this should also keep the hose fittings under positive pressure so that even if DMF gets on them and a fitting isn’t perfectly airtight, the DMF shouldn’t seep in.I'm also going to discuss other materials with the customer, since Teflon hose is fairly rigid. His material compatibility testing is done with the samples submerged and soaked in the hot DMF, but if it actually gets out and sprays, things shouldn’t be swimming in it for hours, and it won’t remain hot. If a more flexible hose type needed to be replaced every year or two, that’s not the end of the world.

author: tooki
author_rank: Super Contributor
timestamp: December 06, 2023, 08:01:52 am
content: Quote from: Neomys Sapiens on December 03, 2023, 05:32:47 amNo worries, I can find them if need be (for future projects). I already have a contact at Glenair, which I assume is one of the ones you’re thinking of.Quote from: Terry Bites on December 05, 2023, 08:59:39 amHmm, and the Bulgin website actually seems better than many: they at least have high-level overview PDFs comparing the series. (I amsoover modern component websites which essentially only let you browse at the SKU level. Gimme an old-fashioned catalog, dangnabbit!)

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: December 08, 2023, 11:41:34 pm
content: Quote from: tooki on December 06, 2023, 08:01:52 amAmphenol, ITT Csnnon and Glenair have some too, but I was thinking of those:https://detoronics.com/https://martec.solutions/https://www.daitron.com/hermetic-connectorshttps://www.dietzegroup.com/en/glass-to-metal-seals/https://www.american-micro.com/connectors.asp