55 Dissolved Oxygen Instrument

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The YSI model 55 dissolved oxygen and temperature handheld instrument has been discontinued.

YSI will continue to support existing model 55’s through 2020. The YSI Pro20i, Pro20, and ProODO handheld instruments are suitable replacements. See the Pro Series Guide for discontinued YSI handheld instruments and their replacements.

  • Overview

    Offering push-button calibration with a built-in calibration chamber, direct salinity, and altitude compensation, the YSI 55 provides simultaneous readings of oxygen and temperature.

    Dissolved oxygen readings are automatically compensated for temperature.


    • Large, backlit display
    • 12, 25, or 50 foot cables
    • IP-65 water tight
    • Low-battery indicator
    • CE compliant

    Includes: Instrument, attached cable, probe, and a 5775 Membrane Kit

  • Specifications
    Certifications CE compliant, IP-65 (water resistant)
    Graphic Display backlit display, Graphic
    Logging Capabilities Single
    Measurement Range Dissolved Oxygen-0 to 200% air saturation/0 to 20 mg/L, Temperature--5 to 45°C
    Parameters Measured Dissolved Oxygen, Temperature
    Power 2 alkaline C-cells provide 400 continuous hours at ambient temperature without backlight
    Sampling Yes
    Unit of Measure Dissolved Oxygen-% air saturation, mg/L, Temperature-°C
    User Calibratable Yes
    Warranty 2-year instrument
    Waterproof IP-65 (water resistant)
  • Accessories

    Membrane Kit, Standard, includes electrolyte (1 mil)

    Membrane Kit, Standard, includes electrolyte (1 mil)

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