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How to Calibrate a Pressure Switch

let's start with some basic concepts of pressure switch calibration:

Set point:

This is the pressure that requires the action of the pressure switch, which can be set to operate on either the up pressure (high alert) or the down pressure (low alert). Most switches are designed to operate at a "gauge" pressure set point that is, at pressure relative to atmospheric pressure. Some applications require an "absolute" pressure set point, that is, pressure relative to absolute zero pressure, and for this purpose an absolute pressure switch is required. Ideally, the range of switches should be selected so that the set point is between 25% and 75% of this range.

Adjustable Pressure Switch GE-208

Adjustable Pressure Switch
Made by A.YITE TECH, GE-208 series

Dead zone or reset back difference:
This setting determines the pressure change required to reset the switch to the normal state after the action is determined. Dead zone or reset or switch difference is the difference between the rising and falling pressure when the pressure switch is working. For a pressure switch with a fixed return difference, it is usually about 1% to 3% of the switch range. For reversible pressure switches, adjustments can be made between about 5% and 12% of the switch range.

Pressure switches are ubiquitous devices. It's almost anywhere in your factory. But how do you calibrate this simple device? Here's the answer. Just follow the simple steps I outline below.

Before calibrating the pressure switch, please confirm the following:
Set value of pressure switch
The return error or dead zone of the switch

The pressure switch is also decompressed and isolated from the process. If the voltage or energy exposed when the switch is turned on is inherently unsafe, follow the steps specified by the factory. For example, if you are in an explosive environment, use a continuously monitored gas detector to monitor for the presence of an explosive gas.

Digital Differential Pressure Switches with 2 set points

Digital Differential Pressure Switches with 2 set points
No need calibrate, easy adjust by Button Key

Pressure switch calibration procedure
Step 1:
Connect the pressure switch to the pressure source, for example by connecting the air source to a manual pressure regulator and test gauge
Step 2:
Use an ohmmeter or digital multimeter (DMM) set to the continuity range to check and verify that the switch contacts are as shown: NO (normally open) and NC (normally closed).
Step 3:
Connect the ohmmeter or DMM between the normally open contact (NO) and the switch's common terminal (C). The meter should show "open circuit". Adjust the manual pressure regulator to increase the pressure to the set point of the pressure switch until the contact switches. The meter should now show "short circuit". Take a pressure reading and write it down. The pressure is the switch set point for the "up" pressure.
Step 4:
Increase the pressure of the switch to the maximum rating. Slowly lower the pressure on the switch until it switches from off to on again. Write down and record the pressure reading. The pressure is a "drop" pressure switch setting.
Step 5:

The pressure difference between the up and down pressure Settings can be obtained from the readings. This is called the "dead zone" of the switch. The calculated dead zone shall be equal to or less than the manufacturer's dead zone.

The maximum dead zone is usually specified by the manufacturer. If the maximum dead zone exceeds the manufacturer's recommendation (dead zone on the nameplate of the pressure switch), the pressure switch may become unusable.

To calibrate the low pressure switch, perform the above steps in the following order: 1-2-4-3-5



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