The Interpump H450 automatic pressure regulator valve is a manually-adjustable, pressure-operated device which, according to its setting, limits the pump/system pressure by conveying the excess of water to the by-pass. Moreover, when the outlet flow is blocked, this device totally releases the flow – and keeps under pressure the portion of the system following the valve, while it sets the pressure to zero in the portion of the system preceding the valve. 400 Bar max pressure. 8-50 Lpm max flow. 85°C max water temperature. Trapped pressure valve. Brass construction. 1/2"BSPF inlet. 1/2"BSPM outlet. 1/2"BSPF bypass.