- Both can be considered as technically equivalent but each has characteristics which may make it more suitable for a specific application.
Contacting Containment Seal
A contacting containment seal operates with the two seal faces in contact while the pump is in operation. This results in a dry sliding interface between the faces. This condition will quickly result in a seal failure in a typical mechanical seal. A contacting containment seal, however, has been designed with very light spring loading, approximately 10 per cent of the loading of a typical seal, to reduce wear and heat generation. In addition, the containment seal chamber is maintained at a very low pressure (less than 10 PSI or 0,7 bar) to further reduce face loading. The seal face materials are also specifically selected for these dry running conditions. Typically, the carbon seal face is formulated with a high graphite content to provide self-lubrication. The seal faces themselves are sometimes provided with face features which help control loading and keep the sliding interface clean and free from wear debris. The advantage of a contacting mechanical seal is that the faces are, by definition, in contact. This means that there is virtually no fluid film between the faces which results in very low leakage. In normal operation, the emissions across the seal are lower than other competing designs. The seal faces can operate successfully over a wide range of speeds, including very low speeds.
To read more of Michael Huebner’s article, or to submit a question relating to sealing solutions, please contact the editor Deirdre Morgan.