High Temperature alternative to Natural Rubber 4

[Sheeny]

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?

 

[Hush]

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.

 

[TVP]

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:

http://www.dupont-dow.com/Header/index.asp

http://www.dowcorning.com/content/rubber/

http://www.gesilicones.com/silicones/americas/business/default2.html

 

[CoryPad]

Another supplier is Dyneon, with info at:

http://cms.3m.com/cms/US/en/2-86/izruzFE/view.jhtml

 

[MASSEY]

We use Viton material for hi-temp bearing applications up to 200C.

Specs. for the material can be seen at:

http://www.sealjet.com/materials/SJVT.html

We buy Viton seals made for particular bearings from Clark Seals:

http://www.clarkseals.com/

And when we need something special we buy a generic viton seal from Chicago Rawhide and design our components to fit the seals:

http://www.chicago-rawhide.com

Have fun.

 

[ceramicmike]

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:

http://www.omegaslate.com/physical.htm

 

[diamondjim]

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

 

[CoryPad]

diamondjim,

Your answer is confusing. Viton is an elastomeric fluorocarbon made by Dupont Dow Elastomers. Torlon is a thermoplastic polyamide-imide developed by Amoco and now supplied by Solvay. More information is available at:

http://www.dupont-dow.com/Products/Viton/viton.asp

http://www.solvayadvancedpolymers.com/products/bybrand/torlon/0,6647,329-2-0,00.htm