Change PU oring for buna or viton

[Diverspoint]

The difference maybe is that SP gets them directly from the manyfacturer and fresh, as opposed tu us humble citizens that order them from some seller that has them on the shelf for an uncertain amount of time.

 

[halocline]

I usually order o-rings from an industrial supplier like oringsusa. I'm sure their stock is generally pretty fresh. I'm sure there is no disadvantage to buying o-rings like this as opposed to using the ones that are in a SP kit.

 

[Couv]

A couple of days ago I started on a batch of MK10s that have not seen service in probably 10 years or more. Of the seven first stages I opened, three had PU seals. Only one of those three had a piston stem o-ring that came out in one piece-and it looked terrible. This was certainly not the first time I've run into this problem. What a royal pain in the ass it is to remove those hard crumbly specimens. The piston head o-rings were not in any better shape. The other four first stages had EPDM seals (albeit the wrong duro) that came out easily.

Note the green color is not the natural shade for PU seals, it due to a reaction with the brass inside the regulator.

 

[lexvil]

A couple of days ago I started on a batch of MK10s that have not seen service in probably 10 years or more. Of the seven first stages I opened, three had PU seals. Only one of those three had a piston stem o-ring that came out in one piece-and it looked terrible. This was certainly not the first time I've run into this problem. What a royal pain in the ass it is to remove those hard crumbly specimens. The piston head o-rings were not in any better shape. The other four first stages had EPDM seals (albeit the wrong duro) that came out easily.

Note the green color is not the natural shade for PU seals, it due to a reaction with the brass inside the regulator.
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Is SP still using this material in some of their regulators? I feel that they don’t but you process a lot more regs than I do. The PU seals probably justify the service intervals or at least did and are likely the source of the LDS fear mongering about seals “drying” out.

 

[Couv]

I don't see any PU rings listed in any of the SP kits currently available. I admit, I have not done an exhaustive search.

 

[halocline]

I think they switched to 85 EPDM a long time ago, those are usually the ones with the stripes. I'm guessing that they use 85 duro instead of 90 because they're a little easier to install, but that's just a guess. Clearly, 90 duro is better for the high pressure gradient spots.