How to Test a Pressure Switch (6-Step Guide)
Content
By the end of this article, you will know how to easily and effectively test a pressure switch.
All pressure switches must have a dead zone threshold for optimum performance. The dead band is the difference between the pressure rise and fall set points, which can be easily obtained. The dead zone sets the threshold for making and breaking electrical connections in the device. As a handyman, I often have to check and troubleshoot deadband issues on devices like HVAC refrigerators. Knowing the deadband threshold of your pressure switch is the key to understanding and troubleshooting your pressure switch and all other devices it controls.
In general, the process of checking if your pressure switch has a dead zone threshold is simple.
- Disconnect the pressure switch from the device it regulates.
- Calibrate the pressure switch with a DMM calibrator or any other ideal calibrator.
- Connect the pressure switch to a pressure source such as a hand pump attached to a pressure gauge.
- Increase the pressure until the pressure switch changes from open to closed.
- Record the increasing value of the set pressure
- Gradually reduce the pressure until the pressure switch changes from open to closed.
- Record the drop pressure setting
- Calculate the difference between rising and falling pressure in best pints
I will delve into this.
Checking the pressure switch
Checking the pressure switch is not a difficult process. The following procedure will help you accurately test the pressure switch deadband threshold.
Set up your device
First, you need to set up the device; the following steps will help:
Step 1: Disconnect the pressure switch
Disconnect the pressure switch from the device it controls carefully and slowly. Devices controlled by pressure switches include HVACs, air pumps, gas bottles and more.
Step 2: Pressure Switch Calibration
Accurate calibration of the device is essential to detect and correct faults in the switch setpoint and deadband. In addition, calibration saves time by reducing the amount of equipment used. I recommend choosing the right calibrator to automate the calibration process. (1)
Now connect the calibrator (or DMM) to the common and normally open output terminals of the pressure switch.
The DMM calibrator measures "open circuit". Also, make sure the DMM calibrator can handle the voltage being measured - when measuring AC voltage.
Step 3 Connect the pressure switch to a pressure source.
You can connect a pressure switch to a hand pump attached to a pressure gauge.
Increase in pressure
Step 4: Increase the pressure of the pressure switch
Increase the source pressure to the pressure switch setting until it (the pressure switch) changes state from "closed" to "open". Record the pressure value immediately after the DMM shows "short circuit"; however, when using the calibrator, it will record the value - you don't need to record it manually.
Falling pressure
Step 5: Gradually reduce relay pressure
Raise the pressure to the maximum switch pressure. Then gradually decrease the pressure until the pressure switch changes from closed to open. Write down the pressure value. (2)
Dead band calculation
Step 6: Calculate the Deadband Threshold
Recall the following pressure values that you recorded in the previous steps:
- Set Pressure - Recorded as pressure rises.
- Set pressure - Recorded when pressure drops.
With these two numbers, you can calculate the deadband pressure using the formula:
Dead band pressure = Difference between the rising pressure setpoint and the dropping pressure release point.
Consequences of the value of the dead zone
The main purpose of having a dead band (different between pressure increase and decrease points) is to avoid switch bounce. The dead band introduces a threshold value for when the electrical system should open or close.
Thus, for proper operation, the pressure switch must have a dead zone. If you don't have a dead band, your pressure switch is faulty and needs to be replaced or repaired, depending on the damage.
Summing up
As already mentioned, the threshold pressure of the dead zone must be significant for the optimal functioning of the pressure switch and the device on which it operates. The process is simple: set up the pressure switch, connect it to the device, increase the pressure, decrease the pressure, record the pressure setpoint values and calculate the deadband threshold.
I believe that the detailed steps and concepts of this guide will help you test the pressure switch in the easiest way and understand its importance.
Take a look at some of our articles below.
- How to connect a 3-wire AC pressure switch
- How to test a light switch with a multimeter
- Which wire to connect two 12V batteries in parallel?
Recommendations
(1) calibration process - https://www.sciencedirect.com/topics/engineering/
calibration process
(2) maximum pressure - https://www.sciencedirect.com/topics/engineering/
maximum working pressure
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