Automatic valves are defined as those valves which change their state simply as a result of compressed air being present or absent at their inlets. The circuit selector Mod. SCS - 668-06 enables two signals coming alternately from two different points to be channelled towards the same point. Series VNR unidirectional valves allow operation at low pressures both when there is a free flow and during retention. Series VSC and VSO quick exhaust valves are commonly used to increase the speed of cylinders or for rapid depressurisation of tanks containing compressed air. The adjustable valves Mod. VMR 1/8- B10 allow to maintain tank/capacity at a constant pressure value and thus enable a quick exhaust in the atmosphere even in case of an internal overpressure.