Shaft tandem seal arrangements

摘要

An outboard mechanical seal of a tandem shaft seal arrangement has a spring retention sleeve 18 surrounding the rotating sealing ring thereof. A spring plate 16 against which a loading spring 12 acts is adapted to abut the load retention sleeve when the mechanical seal is nearly worn. A barrier liquid vessel 23 in conjunction with a level alarm 27 and a pressure alarm 28 monitors the seal to determine when it is worn viz excess flow past the seal and, when the primary seal fails viz there will be a pressure rise in the barrier liquid.