Checkpoint of Dry Gas seal lift-off

[Zakflz]

hello, I am looking how the dynamic testing of dry gas/ non-contacting seal which are operated in pumps and compressors, I have seen the images of dynamic test rig of the same but could not understand how the testing is being conducted unlike liquid lubricated seal? what's the checkpoint to ensure that the faces are lifted during testing? is there any device which will signify or point that the test faces are lifted

 

[JJPellin]

The leakage rate of seal gas is the only indication. If the seals did not lift off, they should fail quickly. If they did lift off, the leakage rate should be within a defined range for good operation. Normally, seals are disassembled for inspection after dynamic testing. At this inspection, damage would be clearly evident if the faces did not lift off properly.

Johnny Pellin

 

[Zakflz]

Thanks Johnny for the reply.
Is there any prescribed value (in pressure and rpm or pressure difference) where the face should start to lift-off?
What would you recommend to start with the test of these seals?

Zakir

 

[JJPellin]

Only the seal manufacturer can answer these questions. There are too many variables.

Johnny Pellin

 

[Chpal1984]

If like alot of non-contacting designs its a dual seal. Its worth looking at the gas consumption (leakage) over both the inboard and the outboard seals