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by Jeff Hopkins on 8/8/13 8:30 AM
Bulletin expanded from 16 to 80 pages; now covers nitrogen based flow curves for 8 series of Swagelok pressure reducing regulators
Swagelok has just completed an update on its technical bulletin covering pressure-reducing regulator flow curves. The previoius version, which came out in October 2011, was a 16-page reference, which focused on our KPR series of regulators. This new, 80-page version covers everything in the original, plus the KCY, KLF, KHF, KCP, KPP, KPF, and KHP series regulators.
We've noted in earlier blog posts how the flow curve is one of the primary tools for matching a pressure regulator to the job. A flow curve is a simple graph. The vertical axis shows the amount of pressure on the downstream side of the regulator. The horizontal axis shows the flow rate. When you plot the pressure that the regulator can maintain at various flow rates, you end up with the flow curve. But don't let the simplicity of the graph deceive you; it takes a lot of careful testing and lab work to produce an accurate flow curve.
In an ideal world, you'd want the curve to be a flat line: No change in pressure no matter what the flow rate. In the real world, that's not possible. Each regulator has its limits. Remember, it's a pressure regulator, not a flow regulator. When the flow rate gets high enough, the curve on the right side of the graph will slope downward, which is called "droop." That means a relatively large pressure drop downstream. At the other end of the curve a regulator is susceptible to "choked flow", meaning that the regulator is wide open and is no longer controlling pressure.
The updated technical bulletin includes the basics on how to read and use regulator flow curves, common definitions related to pressure-reducing regulators, and supply pressure effect (SPE) values for each model. The new bulletin also adds nitrogen-based flow curves for each model and all control ranges.
When you feel comfortable with the idea behind flow curves, be sure to also download Swagelok Northern California's regulator guide. Our guide likewise discusses flow curves, plus the parts of a regulator and how they work together. It explains some of the potential problems that can crop up when a regulator is put into conditions it was never intended to handle.
More to Come
Swagelok is also working on two more bulletins for pressure regulators. One looks at our K series for liquid applications. These bulletins are derived from real-world testing, not just theory. We have completed the necessary tests and are now preparing the technical bulletin. The other one we're working on covers RHPS series pressure-reducing regulators in sizes 2 inches and smaller. Keep watching this space so you'll know when the new tech bulletins are ready.
Back Pressure Regulators Made Simple: 30 min webinar
Our popular webinar series on regulators will get a new installment on Thursday, August, 22nd at 10am as Swagelok field engineer Eric Kayla returns to discuss back pressure regulators. He'll explain the various parts of a back pressure regulator and how they work, typical variations among different models, and how to get the best use from them. Learn more »
Additional resources
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| Watch our webinar on selecting & sizing pressure regulators presented by Eric Kayla (34:39 min) | Selection & Sizing of Pressure Reducing Regulators (13 pages) |
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