Enhanced Temperature Compensation for Pressure/Level

Seametrics Smart Sensors measure pressure using industry standard strain gauge pressure transducers. Strain gauge pressure transducers consist of a thin diaphragm with four imbedded resisters, in a bridge arrangement. As pressure varies, the output signal from this bridge varies.

Ideally, a pressure transducer would respond only to pressure. In reality, however, pressure readings can vary as temperatures change. Also, each individual transducer introduces variations of its own. Our Standard Compensation uses techniques developed and patented by us for “Digitally-Temperature Compensated Strain-Gauge Pressure Measuring Apparatus”. Before leaving the factory, each sensor is individually calibrated. Using a high precision environmental chamber, numerous sample measurements are taken at 5°C, 20°C, and 35°C at both zero and full-scale pressures. Six calibration parameters are determined from this sample data, three for offset and three for slope. Offset and slope errors are defined as second order functions of temperature.

Parameters for both are determined by least squares fit of data for known temperature and known pressure samples. These parameters are then stored in memory on each individual Smart Sensor.

During operation, uncompensated temperature and pressure data is collected and stored in the sensor memory. When data is retrieved from the sensor, the calibration parameters are also retrieved. The retrieving program, typically our Aqua4Plus2.0 control software, then applies the calibration parameters before displaying the data for export. The resultant data is highly accurate – each data point having been individually adjusted to compensate for temperature variations and individual characteristics of the particular sensor.