If you have ever seen a gas-powered grill, chances are that you have seen a gas regulator. These small devices are what make natural gas useable in everyday life. Naturally enough, gas regulators regulate the amount of gas that flows from a storage tank to some kind of outlet. This outlet usually leads to a flame which is kept active by burning the gas. Without a regulator, everything from fireplaces to grills to welding torches would be less of a tool and more of an explosion. So, how do they work?
The basic design involves a set screw, a rod, a diaphragm, and a valve. When you adjust a regulator by turning a knob, you rotate a screw that moves the diaphragm (the thing blocking the gas intake) up or down. This allows more or less gas to flow, making the flame larger or smaller. This design is fairly simple, but it does come in varieties.
The primary difference you might encounter is between a one-stage (or single-stage) and a two-stage (or dual-stage) regulator. Two-stage regulators still employ the same mechanism as one-stage regulators. The big difference is that the first stage of regulation keeps a constant pressure flowing from the source to the second stage so that you can only regulate the flame within a certain level. Pressures in gas tanks can vary wildly with temperature fluctuations, so ensuring a constant pressure means that you can know how much a flame will grow with each turn of the knob. Otherwise, a small turn could lead to a huge flame one day and a small one the next.