THE CALIBRATION AND USE OF PRESSURE TRANSDUCERS IN TENSIOMETER SYSTEMS

The uncertainty in a transducer/tensiometer system was assessed with t emperature and pressure calibrations. A reference transducer/tensiomet er pair was used to factor out temperature related deviations from two monitoring pairs. The reference pair removed most of the deviations, resulting in a high estimate of precision. In contrast to earlier repo rts of high accuracy, these estimates of accuracy were considerably re duced by a time correlated residual pattern. The calibrations suggeste d that the electronic components may be responsible for these residual errors and illustrated the need for experimentation which isolates th e error among groups of components. The complexity of transducer/tensi ometer networks, and the differing response of each component to therm al loading, demonstrated the necessity of using a reference system, wh ich when properly designed can yield reliable pressure readings for so il water.