Air reservoirs are primarily intended for use in delay circuits in conjunction with flow regulators and pressure - sensitive valves. The circuit is usually arranged so that the air reservoir is connected to the inlet port of an ZNCN/151 pilot sequence valve and is slowly charged with pressure air admitted by a folw regulator ZNCN/650. When the pressure in the air reservoir has built up to a percentage of the supply pressure, the pilot sequence valve opens to admit a pilot signal to the valve controlling the cylinder or other pneumatic device. The timing ranges quoted are necessarily modified by the volume of the associated piping. 

The circuit described are intended to provide a delay, not an accurate timing. The repeat accuracy is approximately 5%.