FUNCTION OF A REGULATOR A regulator may be defined as a “mechanism for controlling or governing the movement of machines or the flow of liquids and gases, in order to meet a standard.” The primary function of a gas or liquid regulator is to match the supply of the fluid moving through it to the demand for the fluid downstream. To accomplish this, it measures the downstream pressure and makes adjustments accordingly. Take, for example, a furnace using some type of combustible fluid as a fuel (See Figure 1). In a steady state operation, the number of molecules of fluid being consumed by the fire must equal the number of molecules of fluid passing through the regulator. Should the load or demand for the molecules decrease, then the flow of the fluid through the regulator must decrease or too much fluid will be forced into the downstream piping causing its pressure (P2) to increase. If the load increases, then the flow through the regulator must also increase to compensate for the increased lose of fluid molecules. Otherwise P2 will decrease from a lack of fluid being available to replenish that being used. To meet these fluctuations in demand the regulator senses the downstream pressure, compares it to the set point pressure (its standard), and opens or closes as neede