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SBE-4 Conductivity Sensor

SBE-4 Conductivity Sensor
SBE 4 series conductivity sensors are modular, self-contained instruments that measure conductivity from 0 to 7 S/m.

SBE-4 Conductivity Sensor

Sea-Bird Electronics

SBE 4 series conductivity sensors are modular, self-contained instruments that measure conductivity from 0 to 7 S/m (Siemens/meter), thus covering the full range of lake and oceanic applications. The sensors (Version 2; S/N 2000 and higher) have electrically isolated power circuits and optically coupled outputs to eliminate any possibility of noise and corrosion caused by ground loops. Interfacing is also simplified by the square-wave variable frequency output signal (nominally 2.5 to 7.5 kHz, corresponding to 0 to 7 S/m). The sensors offer improved temperature compensation, smaller fit residuals, and faster turn-on stabilization times. Supply voltage range is 6 to 24 volts. The SBE 4C is a primary sensor for the SBE 9plus CTD Underwater Unit and SBE 25 and 25plus Sealogger CTD. Available in 6800 meter (22,300 ft) aluminum or 10500 meter (34,400 ft) titanium housing, the SBE 4C has a quick-disconnect fitting to simplify plumbing to the CTD pump. The SBE 4M is intended for long-term moored deployments. Available with a 3400 meter (11,100 ft) or 6800 meter (22,300 ft) aluminum housing or 10500 meter (34,400 ft) titanium housing, the SBE 4M is supplied without the quick-disconnect fitting. The sensing element is a cylindrical, flow-through, borosilicate glass cell with three internal platinum electrodes. The electrode arrangement offers distinct advantages over inductive or open external field cells. Because the outer electrodes are connected together, electric fields are confined inside the cell, making the measured resistance (and instrument calibration) independent of calibration bath size or proximity to protective cages or other objects. The cell resistance controls the output frequency of a Wien Bridge oscillator circuit. A unique Sea-Bird design feature introduces a fixed conductivity offset, permitting the instrument to measure conductivity down to 0 for fresh water work.

Documents

Brochure
Brochure SBE-4C - Download

Application Note
AN 02D: Instructions for Care and Cleaning of Conductivity Cells (03/14) - Download
AN 06: Determination of Sound Velocity from CTD Data - Download
AN 10: Compressibility Comp of SBE Conductivity Sensors (05/13) - Download
AN 70: Installing Anti-Foulant Device Mount Kit on SBE 4, 16, 19, and 21 Conductivity Cells - Download
AN 71: Desiccant Use and Regeneration (drying) - Download


Correlated

SBE-9plus Underwater Unit
The standard SBE 9plus underwater unit has an aluminum housing rated to 6800 meters (22,300 ft), and is supplied with one conductivity and one temperature sensor (fitted with a TC Duct and constant-flow pump), and an internally mounted, temperature-compensated Paroscientific Digiquartz pressure sensor for 6800 meter (10,000 psia) full scale range.
SBE-53 BPR Bottom Pressure Recorder
The SBE 53 BPR measures full ocean depth water level with extremely high resolution, accuracy, and stability. The BPR combines a uniquely precise and stable time base with low-power frequency-acquisition circuitry, Paroscientific Digiquartz® pressure transducer, non-volatile 32 MB FLASH memory, and a precision thermometer, to provide unprecedented bottom-pressure recording capability. An optional SBE 4M conductivity sensor can be added to provide salinity data.