7 Facts About Regulators from a Swagelok Engineer
by Taryn Hardes, on Tue, May 27, 2014 @ 15:05 PM
Swagelok Field Engineer Eric Kayla popped by Edmonton Valve recently and was kind enough to give a quick training session to our account managers and customer service representatives. Here are 7 facts straight from the expert.
RHPS Series regulators come in a variety of configurations. For more information about K Series Flow Curves, download the newly updated bulletin here.
Filters can minimize creep
Upstream filtration is a good way to prevent creep. Filtration will remove particulates from the process stream before it reaches the regulator, which will minimize any potential seat damage.
Regulators control pressure, not flow
Regulators reduce the pressure of a gas or liquid from a source, such as a cylinder or compressor, to a lower pressure required by a device, such as an analyzer. Regulators are used to allow high pressure fluid supply lines or tanks to be reduced to safe and/or usable pressures for various applications.
Never use a regulator for a shutoff device
Try using an appropriate shutoff valve (like a ball valve) upstream of the regulator instead of using a regulator for shutoff.
Two-stage regulators can minimize Supply Pressure Effect
Supply pressure effect (SPE) is an effect on the set pressure of a pressure reducing regulator as a result of a change to inlet pressure. This is normally experienced as an increase in outlet pressure due to a decrease in inlet pressure. This can be minimized by using a two-stage regulator, such as the KCY, or by using 2 pressure reducing regulators in succession.
An increase in flow causes a decrease in outlet pressure in the case of pressure reducing regulators
This is called droop. It is primarily caused by the set spring. The more flow required, the more the set spring relaxes and loses load force, causing the outlet pressure to drop.
Droop can be prevented in several ways
By using a longer spring or by using a dome loaded regulator, the effect of droop can be minimized. You can also use a regulator with external feedback or with a pilot regulator, as they have flatter flow curves than a spring loaded regulator.
Most Swagelok Flow Charts use Nitrogen at 70°F/20°C
If your system fluid is not nitrogen, then there is a coefficient chart for you to recalculate the scale of the flow chart. If your system is held at a temperature other than 70 F, then there is another coefficient chart for you to recalculate the scale. Both these calculations are key in properly sizing a regulator for your application. In these cases, the shape of the flow curve will not change, just the scale of the chart will.
For assistance in selecting the right regulator for the job, download the newly updated Flow Curve Technical Bulletin from Swagelok.