Splitting the cost

Mechanical seals are an integral part of power transmission systems which need to prevent leakage between a rotating shaft and its housing under conditions of extreme pressure, shaft speed and temperature.

They can be single or double acting. Single seals have one sealing gap. The lubrication film required by the sliding seal faces is provided by the medium to be sealed.

By contrast, the lubrication film required by the faces in double seals is provided by a higher-pressure buffer medium (sealant liquid) that is compatible with the pumped product. The sealant liquid is at a higher pressure, so any leakage across the faces will be of the sealant liquid into the pumped product. This buffer serves to separate the product and the atmosphere.

Common applications for mechanical seals include pumps, agitators or mixers; marine stern tubes (propeller shafts); gas seals (spiral groove seals); and cryogenic seals. The seal can be internally or externally mounted.