Calibration Procedures for P Series Single Set Point Pressure Switches

Easy-to-follow pressure switch calibration instructions for Ashcroft® P Series pressure switch.
JOIN THE ASHCROFT COMMUNITY
Facebook: / ashcroftinc
Twitter: / ashcroft_inc
LinkedIn: / 72644
UA-cam: / ashcroftinc
VIDEO TRANSCRIPT:
Welcome. This video will detail calibration procedures for the P-Series Pressure Switches.
We have a P-Series explosion-proof switch here. It has a dual chamber design, which means that the adjustment is separate from the electrical for safety. The electrical is located on the top of the switch in the explosion-proof housing. We would remove the cover and connect the microswitch in the same manner as we’ve done with the other switches.
The white wire is connected to the common contact, the blue wire is connected to the normally open, and the red wire is connected to the normally closed contact.
So, the first step is to exercise the switch three times. You exercise the switch by starting at 0 pressure, and taking it to full scale of the switch, which in this case is 100 pounds.
We are going to set this at 80 psi on the increasing. So to do this, we will set the pressure on the switch to 80 psi. We will make sure it is right on 80 psi. With it set at 80 psi, we’re going to adjust the switch to turn it off by turning the adjustment knob clockwise, and then we’re going to adjust it to turn back on.
It turned off. So at this point, we would turn it back, counter clockwise, until it just turns on. And we want to do this slowly, so that you get a very accurate initial set point. Now to make sure that it’s at the set point, we will take it back to 0, and then measure the exact set point.
And it looks like it’s just about on 80. Now we’ll lower the pressure and measure the point at which it turns off when the light turns back to red. This will be the deadband of the switch. So we slowly lower the pressure, just till it turns off. And then we measure that point that it turned off, which is approximately 71.5. So the deadband would be the difference with 80 minus 71.5, or 8.5.
So now we will repeat this measurement three times to verify that the set point is repeatable. We are going to set the switch for 20 psi; decreasing set point. To do that, you want to start at 0, take it to the full range of 100 psi, and then back down to 20. And from there, we will adjust the switch to turn off.
Now we are going to bring it back down to 20. And now we’re going to turn the adjuster in the counter clockwise position to lower the set point. We are going to get it to turn on at that point, and then we are going to get it to just turn off.
It turned on, green, which is good. That means the switch has been turned on. We are now going to turn clockwise to get the switch to turn off. And that should be our set point. Now we must go back through the process of taking the pressure down to 0, back to full scale, and measure the set point at 20.
We take the pressure back to 0. We go to full scale, 100 psi. And now we want to set it down just above our 20 psi. And then slowly walk down and measure our set point. And it should turn off close to 20. And it did. Now from here, we would increase our pressure to measure the deadband. It turned on just above 25, so it has a deadband of about 5.
We would repeat this measurement three times to verify that it was repeatable.
Thank you for watching. Please visit www.Ashcroft.com for more detailed product information. Or subscribe to our UA-cam Channel for additional demonstrations.