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Hypalon vs Neoprene

Hypalon vs Neoprene

(OP)
I have a cooling water connection on a diesel engine with a Neoprene jacket. The jacket is getting hard and cracking after about 5 years in service. I was thinking about switching to Hypalon. Is it likely that I will get a longer service life from Hypalon? My goal is 10 years. The joints are supposed to conform to ASTM F 1123 which rules out EPDM for the jacket.

RE: Hypalon vs Neoprene

Exposed to heat and the environment (does the sun ever hit this part?) 5 years is great life.
Yes there are materials that will last longer, but why not keep it simple and just replace it as part of regular maint?
If you call out something special it may never get replaced.

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P.E. Metallurgy, Plymouth Tube

RE: Hypalon vs Neoprene

(OP)
No sunlight, it's in an engine room wrapped in fiberglass lagging.

The reason I want better longevity is because they are very expensive and I have many of them in my fleet. We're overhauling the engines once every 5 years. Replacing the expansion joints is 10% of the midlife overhaul cost of the engines, including labor!

RE: Hypalon vs Neoprene

Hypalon is a trademark for chlorosulfonated polyethylene (CSPE) synthetic rubber. It was a product of DuPont Performance Elastomers, a subsidiary of DuPont. I don't think DuPont makes it any more but there are lots of copycat materials available.

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RE: Hypalon vs Neoprene

The real problem with elastomers is that ones based on the same resin (say neoprene) will have significantly different aging characteristics.
The resins may be different, and fillers and catalysts definitely are.
Often longer life with high temp water means reduced mechanical properties (especially less 'rubbery').
You may need to be looking for a part that is multi-layered, with different compounds inside and outside.

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P.E. Metallurgy, Plymouth Tube

RE: Hypalon vs Neoprene

(OP)
I wonder if metal bellows joints would be acceptable. These engines are resilient mounted so they do move quite a bit. The exhaust outlet is a metal bellows and seems to hold up (two failed years ago due to the flow liner contacting the bellows but a little extra air gap fixed that). They're a heck of a lot less expensive, too.

RE: Hypalon vs Neoprene

(OP)
You weren't exaggerating when you said significant aging differences. I found this very interesting article. http://prod.sandia.gov/techlib/access-control.cgi/... While I don't really understand the results of the testing of EPR rubber, Neoprene aged to 50% elongation in 115-420 days depending manufacturer and Hypalon was 210-720 days. It seems like the Hypalon may last longer but it's not possible to make that conclusion from the information I have.

RE: Hypalon vs Neoprene

My only experience with Hypalon is as insulation in several sets of ignition wires.
... for the same car.
In ignition service, it's crap.

Mike Halloran
Pembroke Pines, FL, USA

RE: Hypalon vs Neoprene

(OP)
Well, I would certainly like to run silicone here as well but I don't know if it conforms to ASTM F 1123. I'm also not mentally prepared to see that price tag.

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