Pressure Switch Calibration

This sounds a lot like a test question.

Calibrate the switches per the manufacturer's calibration procedure.

If you don't know what that is contact the manufacturer and ask.

This information can be found on the manufacturer's web site.

Since you provide no hint of the brand or model number, we cannot help you.

It is unwise to publish your personal e-mail address.

READ THE RULES AND FAQ's.

Finally, if both gauges are the same, why would the procedure be fundamentally different?

...and why would they be connected to the same line when a single pressure switch would do the job?

Hint:
Any pressure switch has a deadband. To avoid dithering or chattering when the applied pressure is right at the trip point, the mechanics of a switch are used to have a reset point which is the pressure at which a tripped switch will reset itself to the normal state.

For a trip-on-rising-pressure, the deadband point is below the setpoint. For instance, a switch that trips at 2.50 bar rising might have a deadband reset point at 2.35 bar.

For a trip-on-falling pressure, the deadband is above the setpoint. For instance, a pressure switch that trips at 2.50 bar falling might have a deadband reset point at 2.65 bar.

But, a pressure switch deadband is a pressure switch deadband; it is what it is. The pressure switch does not know whether you set it for rising pressure or falling pressure, it just trips and resets according to applied pressure.

So the question is, what besides the deadband differentiates the action of one pressure switch set to trip on falling pressure at a 2.1psi, with a 2nd pressure switch set to trip on rising pressure at 2.1 psi?

I think it's a trick test question.

Quite. GA

One hopes that this installation has a non-electrical way of relieving pressure to a safe place. A HazOp Study will determine the correct approach.

First, let me state your question in the way that I understood it.

You have two pressure switches. One is a high pressure alarm to be set to 2.1 psi, and the other is a low pressure alarm to be set to 2.1 psi. If this is correct, the calibration procedure is NOT the same.

High pressure alarm switches are calibrated by slowing increasing the injected pressure while the Low pressure alarm switches are calibrated by slowly decreasing the injected pressure.

regards,

Vulcan (",)