Zero and span may shift due to temperature, repeated loading or sensor aging. The preferred method to adjust zero and span is through the use of external instrumentation. This allows users to track the changes they’ve made and revert back to previous values if needed.

Customers may order pressure detectors with zero/span adjustments directly on the unit. This also allows for zero and span adjustment, but does not allow the user to track changes or revert to previous values. once adjusted, the sensor is no longer calibrated as it was from the factory. Customers will also want to consider the operating environment of the transducer when selecting whether or not to use sensors with zero/span adjustments. If the sensor is going to be inaccessible, then it would be better to not have adjustments directly on the sensor.

A significant advantage of having the adjustment screws is that users can get calibrated, precise output by use of annual testing and certification, even as the transducer wears or ages in service.