Double lip seal effectiveness on fan motor shaft for biogas
Double lip seal effectiveness on fan motor shaft for biogas
(OP)
We have fans that send biogas to a flare. We had a neoprene seal that is basically a hole cut in neoprene with the motor shaft stuck through then the impeller was direct drive mounted to the motor. That leaked too much gas so the OEM switched to a Teflon plate with a hole machined that the shaft fit through with a tight tolerance- still direct drive - still leaked. Now we are looking at a coupled design which gives them more room to put in a double lip seal around the shaft.
I believe this will work but wonder if anyone has an experience to share? We also looked at a John Crane seal but they were very expensive.
We are running the blowers at 3450RPM but only for about 5-10 minute intervals normally about 8 times daily. If the plant is down then they will flare for longer periods but that will be abnormal.
Thanks for any advice
I believe this will work but wonder if anyone has an experience to share? We also looked at a John Crane seal but they were very expensive.
We are running the blowers at 3450RPM but only for about 5-10 minute intervals normally about 8 times daily. If the plant is down then they will flare for longer periods but that will be abnormal.
Thanks for any advice





RE: Double lip seal effectiveness on fan motor shaft for biogas
The most common rotating shaft seals are lip seals that employ a garter spring to maintain a consistent contact force between the elastomer seal lip and shaft surface. The typical surface rubbing speed limit with elastomer lip seals is around 4000fpm.
Teflon is self-lubricating, but it makes a crappy lip seal material due to its tendency to cold-flow.
Take a look at the SKF website for detailed information on elastomeric lip seals.
Good luck to you.
Terry
RE: Double lip seal effectiveness on fan motor shaft for biogas
RE: Double lip seal effectiveness on fan motor shaft for biogas
RE: Double lip seal effectiveness on fan motor shaft for biogas
RE: Double lip seal effectiveness on fan motor shaft for biogas
Do you have a supply of compressed air available?
RE: Double lip seal effectiveness on fan motor shaft for biogas
RE: Double lip seal effectiveness on fan motor shaft for biogas
A nice Forsheda V-ring slid onto the shaft "behind" the impeller and bearing on a nicely finished portion of the fan housing would seal against the face of the housing and has about 10X greater tolerance for radial runout and eccentricity.
http://www.skf.com/binary/21-6109/vr1ad_tcm_12-610...
Vanes on the back side of the impeller can lower the pressure in the seal area, reducing the sealing requirements.
RE: Double lip seal effectiveness on fan motor shaft for biogas
RE: Double lip seal effectiveness on fan motor shaft for biogas
http://www.seals.saint-gobain.com/uploadedFiles/SG...