Jump to content

  • Log in with Facebook Log In with Google      Sign In   
  • Create Account


ChExpress Blog - 10/30/14

Read the latest news from the chemical industry in Christa's blog.

Featured Articles

Check out the latest featured articles.

File Library

Check out the latest downloads available in the File Library.

New Article

Product Viscosity vs. Shear

Featured File

Air Vessel Sizing for Water Hammer Prevention

Teflon Vs Viton Seals


This topic has been archived. This means that you cannot reply to this topic.
1 reply to this topic
Share this topic:

#1 Zir Ferz

Zir Ferz

    Brand New Member

  • Members
  • 3 posts

Posted 14 July 2010 - 05:50 PM

Hi,

I have to purchase pressure/vacuum relief valves for a carbon steel tank storing crude oil. The manufacturer offers two different types of seals material, teflon or viton so I was wondering which one is better for my application?

Thanks!

#2 proinwv

proinwv

    Gold Member

  • ChE Plus Subscriber
  • 348 posts

Posted 15 July 2010 - 06:56 AM

Viton is a fuel resistant elastomer designed for high temperature. In a PV vent it likely will be effective down to about +10 F, and be too stiff for sealing below that. I would still confirm its chem resistance to your product. Buna-N compounds have much better temperature capabilities at low temps. Sometimes, when an elastomer is seated for long periods it can tend to stick to the seat. Seat design has an effect on this as well as the product in contact and temperatures.

Teflon is generally unaffected by fuels and most products. It has a wide temp range and when there is a properly designed seal/seat arrangement, it will seal well in a PV vent application. It is more resistant to the seat freezing in cold weather. Not being an elastomer, it is not as flexible as an elastomer, such as Viton. I like Teflon for the non-stick properties.

As I said the seat/seal interface design is important. Plastic seats can be superior to metal seats.

I suggest that you have a good conversation with tech people at the vent manufacturer. Look at a couple of vent manufacturers too. Also consider if the seat is reasonably protected from sticking due to ice formation, if that is a consideration. Be aware that PV vents do not seal well over time.




Similar Topics