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Ted Mooney, P.E. RET
Pine Beach, NJ
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for Metal Finishing since 1989
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Plumbing stainless steel to pvc pipe
Q. I am building a hydrogen electrolyzer at home for experimental purposes and came across a few problems.
I've got 2 stainless steel 4" diameter SCH80 316 female ended threaded couplings to which I am attempting to screw onto SCH 80 Black PVC male ends. I am using the stainless steel for a contact between the outside of the machine to the power supply and to the inside where I have water and a sodium hydroxide solution and where it will connect to a grade 316 stainless steel screen. The machine is basically an E shape on its side, 1 pipe for water supply, one pipe for hydrogen, the other for oxygen. My problem is I don't have a wrench large enough or pvc and stainless steel threads don't match. The latter I highly doubt, I think it is that my little cheapo plastic belt wrench that only gives 8inches of leverage isn't big enough. I need to know if there is a reasonably priced wrench out there that can get this thing screwed on. I can only get it half way down onto the pvc. My stainless steel coupling will also have a bar welded on the inside to connect the screen to, as well as a bar on the outside to connect it to the power supply. I am spending my personal money on this project and I don't feel it necessary to buy a 200 dollar wrench for a machine that costs 200 dollars. However I'd rather buy a 200 dollar wrench than not get the machine to work. Anyone have any ideas on how to do this. Also I wonder where to get Proton exchange membranes, platinum, or how to make a PEM.
Joe LounsburyStudent/ researcher - Novi, Michigan, USA
2004
A. I'm confident that there are larger strap wrenches available for less than $200, but that may not be the real problem.
PVC and metal are not supposed to be screwed together, I'm afraid. You are supposed to make the transition from one material to the other with flanged fittings because of the difference in coefficient of thermal expansion. With teflon tape as a lubricant, you may get it tight enough to not leak under a limited temperature range, or you may not.
You might want to look up "thermocouple wells", or "pH sensor wells" to see how metallic sensors are usually inserted into plastic piping systems. Good luck with your project.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2004
A. Ask around at the facilities maintenance groups to borrow or check out a LARGE set of Channelock pliers. Both Channelock and Diamond Tool (avail at plumbing supply houses), make slip-joint pliers which will easily tighten your fittings. Teflon tape will handle any pressure/temp you are likely to encounter. Try to find a high quality tape such as Permacel.
James Kingery- Scottsdale, Arizona, USA
2004
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