Two-Stage Pressure Regulator

A two-stage regulator consists of two single-stage regulators combined into one body. The first stage is a non-adjustable, high-pressure stage preset by the manufacturer. It receives the full cylinder pressure (which can exceed 2000 psi) and reduces it to a fixed intermediate pressure (e.g., 200-400 psi). This intermediate pressure then acts as the input for the second stage. The second stage is adjustable by the operator via a control knob. Because the input pressure to this second stage is already reduced and relatively constant, it can deliver a very precise and stable working pressure to the torch, typically between 2 and 15 psi for acetylene and 5 to 40 psi for oxygen.

The main advantage over a simpler single-stage regulator is the mitigation of the ‘static pressure increase’ effect. In a single-stage regulator, as the cylinder empties and its pressure drops, the output pressure tends to rise, requiring the operator to frequently readjust the flame. The two-stage design effectively isolates the final delivery stage from these large upstream pressure fluctuations, resulting in a ‘set-and-forget’ operation with superior flame stability, which is critical for high-quality welding and cutting.