General Description

The SBE 18 pH Sensor uses a pressure-balanced glass-electrode / Ag/AgCl-reference pH probe to provide in-situ measurements at depths up to 1200 meters (3900 ft). The replaceable pH probe is permanently sealed and is supplied with a soaker bottle attachment that prevents the reference electrode from drying out during storage. The sensor and associated interface electronics is a modular, self-contained package that is easy to install, service, and calibrate.

The SBE 18 is intended for use as an add-on auxiliary sensor for profiling CTDs (SBE 9plus, SBE 19 and 19plus SEACAT, and SBE 25 SEALOGGER). Power / signal interface cables and mounting hardware are available separately.

The SBE 18's interface circuits buffer and offset the differential glass- electrode/reference potential to produce a high-level, pH-dependant, output voltage. Computation of pH in engineering units is typically done using our SEASOFT© software.

Sea-Bird calibrates the pH sensor against precision buffer solutions (4, 7, and 10 pH ± 0.02 pH). These calibration results are tabulated on a certificate furnished with each sensor.