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Fluid Systems Engineering & Management Blog

by Swagelok Northern California

Pressure Regulators: Always changing to meet the need

by Rod Fallow, on 6/21/12 5:56 AM

Get to know them better, and you’ll choose yours with confidence

 

industrial regulators

Learn about pressure-reducing models, back-pressure models, gas cylinder changeover models, and vaporizing models. 

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If you are used to working with valves, regulators can seem confounding at first. It’s true that there’s a lot more to a regulator and the job that it performs. In this post we’ll go over some basics that will make it easier for you to select the right regulator for each job. We’ll follow up with more detail about some of the Swagelok® regulators available to you.

Always on the go

Valves are relatively simple devices. A valve is either closed or it isn’t. If you know your basic pressure and temperature information, you can figure out what valve you need. A regulator, on the other hand, is always changing itself as it reacts to the processes going on around it.

A regulator widens and narrows the inlet opening to make sure you get a consistent outlet pressure within a certain range of inlet pressures and flow conditions. You need to know not only the inlet pressure, but also the pressure you want on the way out, and how much flow is acceptable. Remember, regulators regulate pressure, not flow.

Each regulator is designed to work best within a certain range of conditions. Bump up against one end of the range, and the pressure will build up enough to close off the inlet. That’s called lockup. Go all the way to the other end of the range, and the regulator will be wide open, and is no longer regulating pressure. That’s called choke flow.

Each regulator has its own optimal flow range between lockup and choke flow.

Obviously, there are some moving parts inside. Some models use an internal spring to control outlet pressure. Others control the outlet pressure by means of pressurized gas in a dome atop the regulator.

Spring-loaded regulators are a low-cost option, but the design is more susceptible to temperature, shock, and vibration. Dome-loaded regulators are more rugged, but tend to cost more and take up more space. There are also designs that use a combination of spring loading and dome loading.

Cause and effect

At Swagelok, we’re glad to help customers find the appropriate regulator for each job. But you’ll feel more confident in your choice if you take the time to understand your own systems better, and what you are asking a regulator to do within that system.

Even if you already have a regulator in place, changing conditions may require you to replace it with something slightly different. Here’s why: In any fluid system, you are basically moving a liquid or a gas from Point A to Point B. When changes are made anywhere between those points system, the regulator is suddenly required to operate under new conditions.

If someone has tapped a line downstream of the regulator, that changes the flow characteristics. The same is true if someone has added a line. If your plant has been expanded, the distribution system will draw from your main tanks differently.

The same regulator that was ideal for the original conditions might now be undersized or oversized. Understanding the changes will help you select the regulators you need now. Blueprints of your system can help you understand what’s going on, but only if they’ve been updated to track every change since it was built.

Don’t forget the other elements that go along with regulators -- the filters, flange connections, pressure gauges and more. You want all the parts to match their performance.

Full lines

Over the past decade, Swagelok has acquired a pair of companies in order to bring you a full range of regulators for a wide variety of applications. First came Kenmac, and then RHPS. You’ll learn more about them in the next couple of posts. Subscribe »

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Topics:Regulators

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