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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.

  • Features
  • Applications
  • Specification
  • Operates with or without a controller
  • Direct digital readout with OLED 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 & LCD menus
  • Long-life sensors (2 + years typical)
  • Petrochemical plants
  • Refineries
  • Water & wastewater treatment plants
  • Pulp & Paper mills
  • Manufacturing facilities
  • Automotive
  • Semiconductor plants
  • Chemical plants
H2 Specific
Hydrogen Sulfide
Carbon Monoxide
CO2 Carbon Dioxide
Part# 65-2640RK
65-2643RK-05 65-2645RK-05 65-2646RK-05 65-2649RK-CH4
65-2649RK-HC 65-2660RK-02
Sensors Catalytic Galvanic cell Electrochemical Infrared
Measuring Ranges 0 - 100 % LEL 0 - 25.0% Vol. 0 - 100 ppm 0 - 300 ppm 0 - 100% LEL
0 - 100% Vol.
0 - 100% LEL -02 0 - 5000 ppm
0 - 5% Vol.
0 - 50% Vol.
-10 0 - 100% Vol.
Resolution 1% LEL 0.1% Vol. 1 ppm 1% LEL / 1% Vol. 20 ppm / 0.1% Vol. / 1% Vol.
Lower Detectable Limit (LDL) 2% of full scale 0.1% Vol. 2% of full scale
Max Current Draw (24VDC) 160 mA with alarm 1 and alarm 2 active and all relays energized 125 mA with alarm 1 and alarm 2 active and all relays energized
Response Time (T-90) 35 Seconds or less 30 Seconds or less
Life Expectancy 2 to 3 years with normal service 3 to 5 years with normal service 2 to 3 years with normal service 5 years plus with normal service
Accuracy (which ever is greater) ± 5% of reading or ± 2 % LEL ± 0.5% Vol. O2 ± 5% of reading or ± 2 ppm H2S ± 5% of reading or ± 5 ppm CO ± 5% of reading or ± 2 % of full scale
Weather Resistant Patented water repellent sensor coating
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
Relays 5 amp form ‘C’ contacts for alarm 1, alarm 2, and fail
Dimensions Height: 8.5” (215 mm), Width: 5.2” (132 mm), Depth: 4.5” (114 mm)
Display Alphanumeric OLED display. 8 characters per line; 2 lines for gas concentration readout, plus user-friendly calibration and setup
Enclosure Explosion proof for Class I, Div 1, Groups B, C, D.
Enclosure Rating NEMA 4X, explosion proof, watertight, cast aluminum with o-ring seal and epoxy powder coating
Controls Magnet used for calibration functions. Calibrates without opening the housing. Internal push-button controls also available for calibration and setup
Operating Environment
Operating Temperature -40°F to 167°F
-40°C to 75°C
-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
-40°F to 122°F
-40°C to 50°C
Relative Humidity 5 - 95% RH non-condensing
Location Indoor or outdoor. Explosion proof for Class I, Div. 1, Groups B, C, D.
Operating Voltage 10 VDC - 30 VDC
Analog Linear 4-20 mA signal, into 1000 ohms impedance max (24DC), 0 - 500 ohms max (12VDC) corresponding to 0 - full scale
Digital Modbus RTU output standard, fully configurable, 2-wire RS-485, 1200 to 19.2k baud
Approvals 65-2640RK
Controllers Compatible with all RKI Beacon controllers, as well as most DCS / PLC systems : Beacon 110, Beacon 200, Beacon 410, Beacon 800
Warranty One year material and workmanship

Specifications subject to change without notice. Made in the USA

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