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High Temperature alternative to Natural Rubber

High Temperature alternative to Natural Rubber

High Temperature alternative to Natural Rubber

We use rubber sealed rotary valves on our driers in an MDF (Medium Density Fibreboard) plant. The standard spec for the seals is:

Natural Rubber, 70 shore, 50 x 10, 2220 long

In some plant stoppage conditions the temperature in the drier can rise dramatically - typically to around 100 - 120 degrees C but it is not inconceivable for it to go higher (hot gas is supplied from the energy plant flue gas and blended down to 350 degrees C prior to transport to the drier where it is blended down to required temp).

I'm looking for a heat resistant material to replace the rubber seals, so even if the drier goes over temp, the seals are not destroyed.

Any recommendations?

RE: High Temperature alternative to Natural Rubber

Check with an elastomer supplier for the best compound for your application.

Fluorocarbons (Viton), TFE Propylene (Aflas), and Ethelyne Propylenes (Nordel) are typically good for around 200 C. Saturated Nitriles (Therban, Zetpol) range up to 150 C. If you need higher temps there are some exotics such as Kalrez but they'll cost you an arm, a leg, and some other body parts.

RE: High Temperature alternative to Natural Rubber

High temperature elastomer seals are typically made from silicone (polydimethylsiloxane), fluoropolymers like PFA or PTFE, or fluorosilicones.  NBR (acrylonitrile butadiene rubber) is generally good to about 120 C, and HNBR (hydrogenated) maybe ~ 140 C.  I recommend you visit the following websites for more information:




RE: High Temperature alternative to Natural Rubber

We use ceramic as vane seals in rotary valves. We also use diamond ground ceramic to protect the bore, endplates and rotor shaft from wear.

You might like to take a look at the following web page:


RE: High Temperature alternative to Natural Rubber

I would think a viton composite like
torlon would be much better.  Doesn't
viton flex too much?  

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