The LevelVent and AquaVent are calibrated against a range of set reference points to an accuracy of 3 decimal places. During the calibration procedure, the logger is fully submerged in a highly accurate water bath. The bath is set and allowed to stabilize. The pressure is then calibrated to six separate pressure points covering the entire range of pressure for that particular logger to check for any non-linearity. The process is repeated again at two different temperatures to check for temperature effects. Once done, the logger is approved after all specifications for accuracy, precision, stability and hysteresis have been met. The logger should be calibrated for the life-time of the instrument, as long as it is used within its specified range.