Single-stage pressure regulators reduce cylinder pressure to delivery or outlet pressure in one step. The single stage regulator contains a single diaphragm and poppet. The high pressure gas enters the regulator through the inlet pressure chamber. It passes into the low pressure chamber through the valve stem. The flow is adjusted by turning the regulating knob. Turning it clockwise compresses the diaphragm which pushes the valve stem open, so increasing the gas flow through the regulator. Anti-clockwise, of course has the opposite effect and flow is reduced. Whilst the regulator is in use the initial high pressure starts to drop at source, as the cylinder empties. The reduced pressure means that there is less resistance on the diaphragm and poppet, so the regulator begins to open or creep to allow more gas to flow through it. In order to combat the anomaly, it is necessary for the user to adjust the knob at regular intervals; restoring the balance and maintaining the desired pressure flow.
