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Swagelok Allentown

Your Authorized Swagelok Sales and Service Center

Regulator Flow Curve Generator

Welcome to the Swagelok Regulator Flow Curve Generator.

This tool will give you a unique flow curve based on a set of user-specified application parameters for RHPS series regulators. 

What the tool does

You can:

  • View the performance of one regulator in up to four different applications
  • Compare the performance of up to four different regulators in the same application 
  • View any combination of regulators and applications, adding up to four total, on the same graph

How to use the tool

To view Swagelok Flow Curve Generator results, you must disable pop-up blockers.

Within the tool, users will find fields to enter your application parameters as well as fields that populate from a dropdown, such as choosing the series of pressure regulator to compare. 

The first section of the tool defines the units for the application parameters and graph axis labels, as well as back-pressure vs pressure-reducing regulator type and the number of combinations to be compared.

The second section moves to entering the specifics of your application. This is where you will select a RHPS regulator series, gas type, and pressure control range, and enter your inlet pressure, set pressure, outlet tube/piping ID, maximum line velocity, inlet temperature, molar mass, and specific heat.

Note: Outlet tube/piping ID and maximum line velocity will automatically populate based on other entries but can be edited. Molar mass and specific heat will activate when “user specified gas” is chosen for gas type.

The application will then generate a custom flow chart based on these parameters. The flow chart will contain two pieces of information for each regulator chosen.

  1. Flow Curve (solid curved line): This line represents the full capacity of the regulator. It shows what outlet pressure can be expected for a given flow demand as well as the point of choked flow.
  2. Downstream Velocity Limit (solid straight line): This line represents the point at which the downstream gas will exceed the specified velocity. In order to determine the maximum flow for a particular regulator within a specific downstream velocity limit, find the intersection point of this line and the flow curve.

Please note

The flow chart will not show the lock-up pressure for a given application. However, lock-up is factory tested to be not more than 10% of the maximum control pressure of a regulator configuration. This should be factored into the performance of a given regulator within the desired application. To learn more about regulator performance, please see the Swagelok Pressure-Reducing Regulator Flow Curves Technical Bulletin (MS-06-114). To learn more about each regulator series, please see the Swagelok Pressure Regulators, RHPS Series catalog (MS-02-430).


The regulator flow curves in this report were created from equations that use Swagelok product specifications, conventional fluid properties, and fundamental fluid dynamics to approximate product performance. These calculations were performed to consider a specific set of conditions and should not be considered valid outside those conditions. The information is intended to help with regulator selection but cannot duplicate the variety of actual operating conditions.

Safe Product Selection

When selecting a product, the total system design must be considered to ensure safe, trouble-free performance. Function, material compatibility, adequate ratings, proper installation, operation, and maintenance are the responsibilities of the system designer and user.