University of Sheffield

The Application
A prototype fluid separating device, currently being used for research purposes with the potential to develop the unit for use on an industrial scale.
The unit features a rotating 19 mm diameter shaft, with 6 ports along the length featuring in/out feeds for a mixture of cooling purposes and fluid circulation.

The Challenges
The shaft was rotating at 4800 RPM max speed with 4 bar differential pressure acting on the seals. The challenge was the relatively high velocity of the shaft with the combination of 12 seals required (2 per port) in a small envelope. Heat generation was an issue at those speeds/seal combinations.

Our Sealing Solution
12 rotary “flip” seals stacked to form identical chambers. The design supplied was an o-ring energised PTFE lip seal. The PTFE lip sealed the shaft whilst the elastomer o-ring on the seal OD provided static sealing within the housing.
Material selection was PTFE with a small percentage of carbon fibre filler. This was to ensure self-lubrication in both water and air (test media)
The lip seal was specifically designed to suit the application parameters provided and primarily to reduce friction and subsequent heat build-up as much as possible.

The Results
Initial testing (300 hours) has proved that the seals have performed well with no evidence of leakage. The department are now moving forward in the next phase of their testing programme and hopefully moving the unit on to a larger scale production in the near future.