Again, this depends on the mechanical seal type and the application, but generally a mechanical seal has failed if it is leaking excessively and/or cannot maintain the specified pressure.
A mechanical seal can be considered to have failed if:
- There is an excessive loss of sealed product.
- The product or barrier fluid pressure cannot be maintained at the required level.
- There is an excessive loss of barrier fluid.
- There is an excessive flow of barrier gas.
- There is excessive process contamination (barrier fluid, wear debris or other).
As a rule of thumb, “a mechanical seal has failed if it is leaking at a rate of 250 x its theoretical average”