i dont have this information ...but if you need this to help decide to go for dryseals..these are as reliable as oil film seals ...and are already installed in huge centrifugal machines in many plants....the advantage over oil film seal is quiet clear.
dry gas seal are much better than other seal, particularly when discharge pressure is modrate. company like John crane can help u to find a suitable seal.
riaz.
One can only compare the reliability if we know the operating conditions and environment in which these seals should be operating.
Wet seals: No known limits as to seal size/ shaft rpm, sealing pressure etc ……
Dry seals: Since this is relatively new technology (15 –20 years?) the range is limited. However most applications are already covered. One need to be dealing with large shafts (say 250 mm and above), high sealing pressures (say above 120-150 bars) or dirty process gas to discard dry in preference to wet seals.
Wet seals are known to influence the rotor dynamic characteristics of the rotor system (this usually is due to the seals behaving like bearings – depends on operating conditions). In wet seals, there is a chance of contaminating the process gas with oil.
Dry seals also influence rotor dynamics – but this is due to their weight.
If you have electric power and plenty of compatible oil, you do not need any other utilities to operate and maintain wet seals.
Dry seals need clean sealing gas. Nitrogen is also welcome in separating the bearings from seal area. Dry seals usually require higher quality utilities (expensive too).
Maintenance of dry seals is expected to be less costly affair.
With dry seals if you go with bi-directional seals, u may save on spares inventory. But, some people are of the opinion that uni-directional seals are more robust when it comes to sealing.
