SensoControl Pressure Sensor 0psi Reading

Why doesn’t my SensoControl device show zero psi when turned on?

Answer

This is a user expectation that arises from comparisons to mechanical gauges.

Whereas mechanical gauges force the indicator to rest on a stop pin to always indicate zero psi, there are several problems that arise from this technique. For example, most mechanical gauges are very inaccurate in the initial pressure measurement range that occurs as the indicator moves away from the rest pin. It’s important to note that mechanical gauges are selected to read at 50% to 75% of the normal operating range to balance the need for accuracy and provide a margin of protection if the pressure moves higher than normally expected. Why? Because mechanical gauges typically cannot tolerate any over-pressure condition and retain accuracy.

Digital pressure measuring devices work differently. As a result, a zero value might not appear in the display and the unit is still fully accurate (as well as calibrated if stated as such). The reason for that is that the electronic unit has a floating zero since it is not artificially forced by mechanical means as on a traditional gauge. The advantage in this arrangement is that the immediate measurement values going away from zero and back to zero are as accurate as the full-scale readings on these units.

Another bonus is that a SensoControl device can be exposed to an over-pressure condition and (within its limits) return to service with the same accuracy. Forcing a “zero” value on a digital instrument can actually create a fixed offset error from a true value. Ultimately, the end result then is less accuracy of the displayed measurement value.

In summary, the stated +/- tolerance of any SensoControl device allows the appearance of a non-zero value in the display (when there is no pressure exerted on the unit). This is to be considered normal
as such (when in tolerance).