Buyer’s Guide: How To Properly Adjust & Set A Differential Pressure Switch

March 1, 2021

At Mid-West Instrument, we want to ensure that our customers can get the very most out of our products. Our differential pressure switches, for example, are designed to deliver accurate pressure readings in a wide variety of industrial applications, but every once in a while, they’ll need an adjustment. This guide will describe how you can properly—and safely—adjust a differential pressure switch so that you can continue to get the crucial data that you need.

What a Differential Pressure Switch Does

First, it’s important to talk about what a differential pressure switch does. At a very basic level, this device is designed to take the pressure of two different points in a system and tell you the difference. Sometimes these switches need to be recalibrated, and fortunately, they offer convenient setpoint screws that allow you to adjust the pressure. Both the switch point and setpoint pressures can be adjusted this way.

What You Need to Adjust Your Switch

You’ll need a few tools on hand to adjust your differential pressure switch, including:

  • An Allen wrench
  • A variable pressure source
  • A digital multimeter
  • A test gauge

Adjusting Your Differential Pressure Switch

Now it’s time to adjust your switch. First, remove the cover to access the parts you need. You will see three different ports, the HI, the C, and the NO.

Connect the variable pressure source to your test gauge and the HI port. Then set your digital multimeter to 2,000 ohms and connect it across the C and the NO ports. Your multimeter readout should be at 1, which means that this differential pressure switch is set to 30 pounds per square inch differential, or psid.

Now you can use your variable pressure source to apply pressure to the HI port. This will allow you to pick a new setpoint and adjust your switch accordingly. You can also drop the pressure by letting the other port vent. You can experiment by raising and dropping pressure to determine how close you are to the desired setting.

At this point, it’s time to adjust the setpoint screw. Use the Allen wrench to loosen the screw and adjust it until your multimeter reads as close to zero as possible. Now you can tighten the screw back up. The multimeter should read 1 at that point, showing that your switch is in the normal closed position.

Just make sure that you do not turn the screw too tightly, as it is possible to break it if you get overzealous while adjusting it. If you need to keep adjusting your differential pressure switch, repeat the above steps until you get to the setting you prefer.

For More About Our Switches and Industrial Products

If you’re looking for any other products that can operate in high-pressure situations, we can help. Visit the Mid-West Instrument website and learn more about differential pressure switches and the rest of our product offerings. Our experts are here to help you find the equipment you need to handle even the toughest tasks.