Seal arrangement Spiral grooving Seal system and how to seal against leakage of process fluid

摘要

A double back-to-back machine-facing seal for use in sealing a toxic or corrosive fluid having a middle insecticidal fluid chamber provided for use as a buffer fluid, wherein a relatively depressed gas, such as nitrogen, is provided.;The nitrogen gas is maintained at a pressure that exceeds the working fluid pressure by at least 10 psi, and in a preferred embodiment, the spiral pumping grooves are formed and dimensioned in the mating rings of each seal to provide a nitrogen full layer gas from the intermediate chamber to the working fluid Pumping through the first seal into the chamber and from the intermediate chamber through the second seal to the environment outside the housing and sealing region to avoid leakage of the processing fluid into the intermediate buffer chamber and into the air. Contamination of the processing fluid by the buffer gas can be tolerated. The buffer gas may be a relatively inert gas, a gas compatible with the pneumatic fluid that is not hazardous to the environment and also used, and is suitably one of nitrogen, carbon dioxide, air, or rare earth. The seal can be used to seal the processing fluid, which is liquid or gaseous.