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pH/O.R.P. (Redox) Sensor
SBE 27

Print version Configuration options & accessories

SUMMARY

Voltage output pH and O.R.P. measurements
Compatible with Sea-Bird profiling CTDs
Depth rating 1200 meters
Five-year limited warranty.

DESCRIPTION

The SBE 27 pH and O.R.P. (Redox) sensor combines a pressure balanced glass-electrode, Ag/AgCl reference probe and platinum O.R.P. electrode to provide in-situ measurements up to 1200 meters (3,900 ft) deep. The replaceable pH probe is permanently sealed and is supplied with a soaker bottle attachment to prevent the reference electrode from drying out during storage.

The sensor elements and interface electronics are modular and self-contained, providing easy installation, service, and calibration. The SBE 27 is intended for use as an add-on auxiliary sensor for profiling CTDs (SBE 9plus; SBE 19, 19plus, and 19plus V2 SeaCAT; and SBE 25 and 25plus Sealogger). Power / signal interface cables and mounting hardware are available separately.

The SBE 27 interface electronics buffer and offset the differential voltages of the pH reference junction and the electrode potential (in water) between the O.R.P. electrode and the pH reference junction to produce pH and O.R.P. dependent output voltages. Computation of pH and O.R.P. in engineering units is typically done using our Seasoft^© V2 software.

Sea-Bird calibrates the pH sensor against precision buffer solutions (4, 7, 10, pH ± 0.02 pH). The extremely stable O.R.P. circuitry is calibrated at the factory and does not require subsequent calibrations. These calibration results are tabulated on a certificate furnished with each sensor.

CONFIGURATION OPTIONS

A standard SBE 27 is supplied with an XSG connector, plastic soaker bottle, and KCl soaker solution. Options include:

Right angle probe, required for applications where the SBE 27 is mounted to a CTD that is deployed horizontally (for example, in an extension stand below an SBE 32 Carousel Water Sampler).
Wet-pluggable MCBH connector in place of XSG connector

SPECIFICATIONS

	Measurement Range	Accuracy¹	Time Response²
pH	0 - 14 pH	±0.1 pH	1 second
O.R.P.	±1250 mV	±1.0 mV	10 ms
¹Stated accuracy is achievable with frequent field calibrations. ²Time to reach 63% of final value following a step change in the measured parameter.