The heat generated in every mechanical seal must be dissipated or reduced by suitable means. General notes on cooling systems for pumps with unilateral and bilateral bearing are given in API 610. Cooling systems can be designed as buffer systems with an open circuit (buffer fluid unit) or as a closed buffer system circuit. In either case the coolant must be compatible with the product to be sealed. Given high product temperatures, it can be necessary to have a separate cooling housing on the mechanical seal.