Harris Products Group

The basic function of a gas pressure regulator is to reduce unusable high pressure from the source to a lower usable delivery pressure. Two-stage regulators are designed to lower the high pressure in two stages. They require less readjustment and provide a more constant delivery pressure despite changes in inlet pressure. They are exceptionally well suited for high pressure cylinder applications.

Operation of two-stage regulators
Two-stage regulators are two regulators built into a single regulator body. The first regulator (first stage) is preset at a non-adjustable pressure to reduce the incoming pressure to a lower pressure, referred to as the intermediate pressure. The second regulator (second stage) is adjustable within the desired delivery range.

These regulators incorporate all components of a single stage regulator. They also contain an additional stage to include a second pressure adjusting spring, diaphragm, and valve seat assembly. The first stage is not user adjustable. The pressure adjusting spring is "pre-compressed" at the factory. This allows the first stage to feed pressure to the second (adjustable) stage. The normal maximum delivery pressure for two-stage regulators is 500 PSI.

The second stage then performs in a manner similar to that of a single-stage regulator, except that the inlet pressure of the second stage is relatively constant. The two-step pressure reduction produces a final delivery pressure showing little effect from changes in cylinder pressure.

When is a two-stage regulator required?

1.    Applications where the delivery pressure rise from cylinder pressure decay cannot be tolerated.

2.    Situations where proper pressure is critical and the cylinders in use are in a remote or difficult to monitor location.

3.    Typically are not required when using gases from low pressure (<500 PSIG) sources.