RKI Instruments M2A Series Stand Alone Transmitters
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RKI Instruments M2A Series Stand Alone Transmitters


  • Operates With or Without a Controller
  • Direct Digital Readout with OLED Cold Temperature Display
  • Infrared Sensor for Combustibles and CO2
  • (2) Fully Programmable Alarm Relays & Fail Relay

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This unit is equipped with an H2S Hydrogen Sulfide Detector. Electrochemical sensor is used and is a consumable component with a limited functional life. A replacement sensor may be needed at any time.

• Sensors: Electrochemical
• Measuring Ranges: 0 - 100 ppm
• Accuracy: ± 5% of Reading or ± 2 ppm H2S
• Operating Temperature: -40°F to 104°F (-40°C to 40°C)

Part Number: 65-2645RK-05 / H2S
H2S Hydrogen Sulfide Detector Part Number: 65-2428

View Photo of H2S Detector.
H2S Detector Manual (pdf)

Stock # 90419-1

  • Description
  • Tech Specs
  • Datasheets / Manuals 
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The RKI Instruments M2A Series Stand Alone Transmitters are state-of-the-art transmitters 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 are manufactured for NH3, SO2, PH3, AsH3, and HCN.

Product Family: M2A Series, 65-2640RK, 65-2640RK-05, 65-2641RK, 65-2641RK-05, 65-2643RK-05, 65-2645RK-05, 65-2646RK-05, 65-2649RK-CH4, 65-2658RK-CH4, 65-2649RK-HC, 65-2660RK-02, 65-2660RK-03, 65-2660RK-05, 65-2660RK-10
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