Nirile in Caustic

swall · Jun 17, 2004

I previously posted this on the Polymer forum, but since there are some rubber experts here, I am inquiring here.I have an inline caustic washer on a paint line.The parts hang from an overhead conveyor and there is a slot on top of each stage for the parts hangers to pass through.This slot is sealed with a rubber strip on each side for the entire length.In the spray washer (5% sodium hydroxide at 140F)stage, I used EPDM rubber because of its resistance to hot water and caustic.But, I didn't consider the effects of the oil removed from the parts during washing.This oil mist swelled the EPDM sealing strips, scalloping them to the point where the top of the washer is no longer sealed.Would nitrile work in this application?

TVP · Jun 17, 2004

The nitrile rubber would be more resistant to oil, but it is less resistant to sodium hydroxide. Volume swell is estimated to be 10-20%. Fluoroelastomers or perfluoroelastomers would perform the best.

EdStainless · Jun 17, 2004

Hot caustic and oil combined will probably force you into a more expensive compound. Unless you can redesign the seal lips with metal back plates and spring loading so that distortion of the elastomer doesn't have as much effect on performance.

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Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

swall · Jun 17, 2004

We are only talking about 50 feet of 6" rubber strip, so cost will not be an issue.

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