Single-stage pressure regulators reduce the cylinder pressure to the delivery or outlet pressure in one step. Two-stage pressure regulators reduce the cylinder pressure to a working level in two steps.
The best recommended action is to determine how you intend to use the pressure regulator. Generally a single-stage regulator is good for short duration applications; a two-stage regulator is good for long duration applications, such as gas chromatography.
ONE-STAGE REGULATOR
TWO-STAGE REGULATOR
Credits : scottecatalog