Effect of Pressure on Deep-Ocean Thermometers

A laboratory experiment was devised and performed to investigate the pressure dependence of Sea-Bird Electronics SBE35 and SBE3 deep-ocean thermometers. The thermometers were mounted in a massive brass comparator together with a calibrated standard platinum resistance thermometer. The measurements were performed in a pressure chamber in the pressure range 0.1 MPa to 60 MPa. The results showed that both the investigated SBE35 and SBE3 thermometers are pressure dependent, with a pressure sensitivity of +41 mu K.MPa-1 and -77 mu K.MPa-1, respectively. Nevertheless, the results obtained in only one individual device per model (one SBE35 and one SBE3) cannot be generalized and further investigations of a larger number of devices per model are needed.