Whale expansion vessel WS7215 ensures a smooth constant water supply with a capacity of 150ml (1/4 pint). Connect the expansion vessel as close to the outlet of the water pump as possible, or as close to the outlet side if a separate pressure switch is fitted. The Whale surge damper connects directly to Whale 15mm Quick Connect Plumbing or 13mm (1/2") flexible hose (using stainless steel hose clips). Maximum pressure: 4 bar (60 psi).