A valve has a fluid inlet, a housing comprising a first chamber and a fluid passage extending from the fluid inlet to the first chamber, one or more exhaust channels in fluid communication with the first chamber such that, in use, a pressurised fluid entering the first chamber is exhausted through the one or more exhaust channels, a device movable between a closed position and an open position, and a resilient member configured to bias the device towards its closed position. The valve further comprises one or more additional fluid channels having an outlet within each of the one or more exhaust channels that create a Venturi effect in use with the pressurised air exhausted through the one or more exhaust channels.