Control of Pressure
The previous chapter showed how the pressure on a district varies with changes in the demand for gas. When very few appliances are in use pressures are at their highest. As more and more gas flows, the loss of pressure is greater and district pressures are reduced. But, if customers’ appliances are to work satisfactorily, there are
limits below which the pressure must not be allowed to fall. And gas suppliers are required by statute to maintain a safe minimum pressure at all times, see Table 7.1.