|The single or 1 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.
||Two stage regulators work in much the same way as single stage regulators with one main difference. Rather than having one diaphragm and poppet, they have two. The first stage reduces the pressure, but as the cylinder empties, the pressure exerted on the first stage decreases allowing the flow to increase. It happens in just the same way as the single stage regulator, but here is the clever bit: the outlet pressure still remains constant with no need to adjust the regulating knob. The reason for this is the second stage. This second stage is constructed in a similar manner to the first, but the pressure being exerted on the second diaphragm and valve stem is much less. Stage one is regulating very high pressures from the cylinder and reducing them down to extremely low pressures. Therefore it is low pressure gas that passes through the second poppet. The regulator outlet pressure doesn't creep because the low pressure passing through the second stage is too low to cause an imbalance on the diaphragm.