Figure 3.

Measurement of the vulnerability to cavitation of cell pressure probes. Seven different pressure probes were cavitated 25 to 50 times each and these data are typical of many experiments performed. Pressure was a function of the temperature of the sealed microcapillary. In the case of oil-filled probes there was a linear relation between pressure and temperature whereas for water-filled probes the relations were non-linear (data not shown). A, Water-filled pressure probes cavitated at less negative pressure than oil-filled probes. Attempts to hold the pressure very near the threshold of cavitation generally failed within seconds (first two attempts in water-filled probe) and last attempt in oil-filled probe. B, Long-term stability of an oil-filled probe that could hold −1.0 MPa for more than 1.5 h without cavitation; water-filled probes could hold −0.5 MPa for the same period of time (data not shown).