What are the symptoms of a mechanical seal that is not running properly?

There are varying symptoms of failing mechanical seals based on the seal type. In the case of dry seals, higher than normal nitrogen consumption is often an indicator of a problem as is hissing or puffing sounds from the seal housing. A red flag is also raised when a flowmeter is placed in-line and the indicator ball is above allowable limits (one to two standard cubic feet/hour per inch of shaft diameter) or if the indicator ball is bouncing in the meter. As for lubricated or “wet” seals, any that are losing liquid at an increased rate or have run totally dry prove to be problematic.