Selecting Pressure Regulators
Most specialty gases are supplied in cylinders compressed to high pressures. Pressure regulators reduce these high pressures to lower pressures that
can be safely used in an operating system. Proper regulator selection is critical for both safety and effectiveness of operating systems.
Note: Regulators are designed to control pressure. Generally they are supplied with gauges that indicate pressure. Regulators do not measure or control
flow unless equipped with devices (such as a metering valve or flowmeter) specifically designed for those purposes.
Many variables are involved in selecting the proper pressure regulator. While certainly not a comprehensive list, the following provides some of
the more important considerations. To further assist in making proper regulator selections, refer to the Equipment Recommendation
1. Materials Compatibility: Materials used to construct regulators must be compatible with the gas—especially those
materials (wetted parts) in contact with the gas. Advanced offers a wide variety of regulators with various materials of construction to help ensure that
the correct regulator is available for your needs.
2. Inlet Pressure Rating: Regulators must be able to safely handle incoming gas pressure. Here again, a wide selection is
available which includes regulators that handle inlet pressures of 6000 or even 10,000 psig.
3. Delivery Pressure Range: Regulators must be able to reduce pressure to levels compatible with the operating system and
consistent with process needs. Advanced’s extensive line of pressure regulators provides numerous choices with delivery pressure ranges available
as low as 3.5–8" H2O, or as high as 300–6000 psig.
4. Gas Purity: Like all system components, regulators should be selected to protect the purity of the service gas. As an example,
regulators with stainless steel diaphragms are recommended for high purity applications because they tend to be more “diffusion-resistant” than
those with elastomeric diaphragms. For low particulate applications, consideration should be given to selecting regulators with machine welded VCR® connections.
Optional Helium Leak Tests also help to ensure the integrity of regulator purchases.
5. Single- or Two-Stage Design: Single-stage regulators reduce pressure in one step. As gas is consumed, pressure in the cylinder
(and therefore the inlet pressure to the regulator) decreases. This reduced inlet pressure provides less force against the regulator valve, causing the
regulator to open wider, resulting in an increased delivery pressure setting. Therefore, single- stage regulators are most useful in applications where:
- periodic manual adjustments to delivery pressure settings are not a problem or
- inlet pressure remains relatively constant, such as where the gas is a liquid under pressure (e.g., Carbon Dioxide or Propane).
Two-stage regulators are actually two regulators housed in one body. The first regulator (first stage) is nonadjustable and reduces incoming pressure
to an intermediate setting (typically 250 to 300 psig). The second stage is adjustable and reduces intermediate pressure to final desired delivery pressure.
Because the second stage sees only relatively minor inlet pressure changes from the first stage, two-stage regulators maintain steady delivery pressure
and do not require periodic adjustment. They are well suited for applications where constant delivery pressure is essential.
6. Line or Cylinder Regulator: Cylinder regulators, as their name implies, are connected directly to gas cylinders. Typically
offered in both single and two-stage designs, cylinder regulators normally have inlet and delivery pressure gauges.
Line regulators, on the other hand, are used directly in piping systems, such as downstream of a manifold or bulk storage vessel. Because inlet pressure
in piping systems is normally constant, line regulators are typically single-stage configurations with delivery pressure gauges only.
7. Other Considerations: Other criteria for consideration include operating temperature, flow requirements, regulatory issues
(e.g., medical regulators manufactured to FDA standards), attached poppet configurations, and so on.