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RKI Instruments M2A Stand Alone Sensor / Transmitter with J-box, Sulfur Dioxide (SO2) 0-6 ppm - 65-2648RK-SO2

RKI Instruments M2A Stand Alone Sensor / Transmitter with J-box, Sulfur Dioxide (SO2) 0-6 ppm - 65-2648RK-SO2

Item #
RKI Instruments



    65-2648RK-SO2 M2A Stand Alone Sensor / Transmitter with J-box, Sulfur Dioxide (SO2) 0-6 ppm by RKI Instruments

    The RKI M2A™ is a state-of-the-art transmitter that can operate as an independent, stand-alone monitor or as part of an integrated system. The M2A connects with an analog or digital signal to virtually any controller, PLC, or DCS. Setup procedures are simplified with user friendly push buttons and OLED menus. It utilizes a magnetic wand technique for performing non-intrusive calibration. The M2A provides an automatic zero drift correction feature, which results in more stable readings and reduces the need for adjustments due to sensor aging.

    The housing of the M2A does not need to be opened for zeroing or calibration, making it unnecessary to declassify the area for routine maintenance. It is designed so that a complete field calibration can be performed by one person. Sensor construction is rated Class I, Div. 1 Groups B, C, D for flammables, CO, H2S, O2, and CO2, and Class I, Div. 2 for all other toxics.

    The transmitter provides a 4-20 mA output in addition to a Modbus digital output. It also has two levels of alarms with relays, plus a fail alarm with relay. A digital display of the gas concentration, as well as alarm and status lights, can be viewed through the front window.

    The toxic sensors are electrochemical type plug-in sensors, which provide high specificity, fast response, and long life. The plug-in design allows quick replacement in the field with no tools required. Toxic sensors are designed for use in Class I, Div. 2 hazardous locations. Sensors available for NH3, SO2, PH3, AsH3, and HCN.

    The M2A represents the latest leading edge technology in sensor / transmitters today.


    • Operates with or without a controller
    • Direct digital readout with OLED cold temperature display
    • Available gases include LEL, O2, H2S, CO, CO2, and 100% Vol CH4 / Toxic gases include NH3, SO2, HCN, and more
    • Infrared sensor for combustibles and CO2
    • 4-20 mA & digital Modbus outputs standard
    • 2 fully programmable alarm relays & fail relay
    • Non-intrusive calibration via magnetic wand
    • Explosion proof construction
    • Patented water repellent sensor cover
    • User friendly setup, push buttons & OLED menus
    • Long-life sensors (2 + years typical)

    *Please note we can only ship RKI products to customers within the United States

    Hydrogen Sulfide
    Carbon Monoxide
    Arsine (AsH3)
    Ammonia (NH3)
    Phosphine (PH3)
    Hydrogen Cyanide (HCN)
    Sulfur Dioxide (SO2)
    Carbon Dioxide
    Galvanic cell
    Measuring Ranges
    0-25% Vol.
    0-100 ppm
    0-300 ppm
    0 - 1.5 ppm
    0 - 75.0 ppm
    0 - 1.00 ppm
    0 - 15.0 ppm
    0 - 6.00 ppm
    0 - 5000 ppm
    0 - 5% Vol.
    0 - 50% Vol.
    0 - 100% Vol.
    0.1% Vol.
    1 ppm
    0.01 ppm
    0.1 ppm
    0.01 ppm
    0.1 ppm
    0.01 ppm
    20 ppm / 0.1% Vol. / 1% Vol.
    Lower Detectable Limit (LDL)
    0.1% Vol.
    2% of full scale
    Response Time (T-90)
    35 Seconds or less
    60 Seconds or less
    30 Seconds or less
    Max Current Draw (24VDC)
    125 mA with alarm 1 and alarm 2 active and all relays energized
    Life Expectancy
    2 to 3 years with normal service
    Accuracy (which ever is greater)
    ± 0.5% Vol. O2
    ± 5% of reading or ± 2 ppm H2S
    ± 5% of reading or ± 5 ppm CO
    ± 10% of reading or ± 5% of full scale
    ± 5% of reading or ± 2% of full scale
    Alarm Settings
    Two fully programmable alarm set points, increasing / decreasing, latching / self-resetting, on delays, off delays, normally energized or de-energized
    Alarm Indication
    Visual LEDs. Alarm 1=Amber; Alarm 2=Red; Fail=Red
    5 Amp form 'C' contacts for alarm 1, alarm 2, and fail
    Height: 8.5" (215 mm), Width: 5.2" (132 mm), Depth: 4.5" (114 mm)
    Alphanumeric OLED display. 8 characters per line; 2 lines for gas concentration readout, plus user-friendly calibration and setup
    Sensor Rating
    Non explosion proof construction, designed for Class I, Div. 2, Groups B, C, D (no certification)
    Housing J-Box
    NEMA 4X, explosion proof, watertight, cast aluminum with o-ring seal and epoxy powder coating
    Magnet used for calibration functions. Calibrates without opening the housing. Internal push-button controls also available for calibration and setup.
    Aluminum / Plastic (non explosion proof)
    Operating Environment
    Operating Temperature
    -4°F to 113°F
    -20°C to 45°C
    -40°F to 104°F
    -40°C to 40°C
    23°F to 104°F
    -5°C to 40°C
    14°F to 104°F
    -10°C to 40°C
    -40°F to 122°F
    -40°C to 50°C
    Relative Humidity
    5 - 95% RH non-condensing
    Indoor or outdoor
    Operating Voltage
    10 VDC - 30 VDC
    Linear 4-20 mA signal, into 1000 ohms impedance max (24DC), 0 - 500 ohms max (12VDC) corresponding to 0 - full scale
    Modbus RTU output standard, fully configurable, 2-wire RS-485, 1200 to 19.2k baud
    Compatible with all RKI Beacon controllers, as well as most DCS / PLC systems: Beacon 110, Beacon 200, Beacon 410, Beacon 800
    One year materials and workmanship

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