Control Valve Sizing: A Quick Guide

Control valve sizing is critical to efficiently produce oil and gas.

In this video tutorial, Mike Fick explains how to use the Kimray Control Valve Sizing program to make sure you’re getting the right valve for your application.

How to Size a Control Valve

I start by using the gas sizing tab. The process will be the same for liquid sizing.

You can enter up to four different conditions, and the labels on the top can be changed to name each one.

  • First, fill out the first six fields. Notice that the Cf value of 0.75 is already filled in. After you select a valve, you can go back and plug in the Cf value of that valve to make sure it still works.
  • There are two buttons—”Calculate flow rate” and “Calculate Cv.” If you already have a valve and want to know the flow rate, fill in the Cv value and click “Calculate flow rate.”
  • In my first example, I fill in the flow rate and click the Calculate Cv button. The results are three Cv values, one for each condition. It also displays how high and how low the upstream and downstream pressures can be before we reach critical flow. This will be helpful to you if you’re trying to figure out what those limits are before you go into critical flow. You can also include notes at the bottom and expand the box sizes if necessary.
  • Next, you can search for the correct valve. Make sure the boxes are checked so the calculator will use all three of these conditions in the search.

How to Size a Control Valve: Example 2

In the second example, I select a back pressure regulator and then add a minimum and maximum set point.

  • I set the pressure as low as 15 psi, and as high as 80 psi. Then the program displays valves that encompass that range.
  • I use 300 psi for our maximum working pressure.
  • We recommend that the percentage open be between 20 and 80%. For more information on this, watch our video about Cv.
  • I then click “Find available products.” Since there are multiple results, I drill down a bit deeper.
  • Next, I open the subcategory selection and limit it to back pressure regulators. Then I drop down the connection size and choose 3 inch. This narrows down the results to 3 valves with differing connection types and trim sizes.
  • In the results, you can scroll to the right to see what the Cv is at each 10% increment of stem travel. This can help you decide which valve will best suit your needs. You can also click “Draw Graph” to see a graph of those data points.
  • In the video, I select a 3-inch, 300 RF with a 2-inch equal percentage trim. The Cf is 0.75, which means we don’t have to go back and change the original Cf that we entered in the calculations. However, if it did need to be changed, we could click the Cf value here and it would change in the calculator.
  • Then, I scroll back up and click the “Calculate Cv” button. This allows me to see if that valve will still work for my conditions.
  • Sometimes, you may end up with no results. I’ve added a fourth condition with a very low flow rate compared to the others.
  • Now I calculate the Cv and check this box to include the new condition in the results.
  • When I click “Find available products,” I get a message with five possible ways I could change my settings to see more results.

If you need further help with the sizing a control valve, contact your local Kimray store or authorized distributor.