S2 Series – Gas Sensor/Transmitter


The RKI S2 series gas sensor/transmitters are highly reliable and very cost effective for the detection of common gas hazards. The S2 series are available for LEL, H2 Specific (LEL, and ppm), Oxygen, H2S, CO, and for a variety of toxic gases. The transmitters for LEL, H2 Specific, Oxygen, H2S, CO2, and Carbon Monoxide are explosion-proof with flame arrestors, and approved for use in hazardous areas (Class l, Div 1 Groups B, C, D). An optional non-explosion proof version is available for oxygen, H2S, CO, and CO2 in Class 1 Div 2. LEL sensors are available using catalytic bead and infrared technologies.

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, AsH3, Cl2, ClO2, HCN, PH3, and SO2.

The S2 transmitters can be used either indoors or outdoors. The flame arrestors for the explosion-proof versions utilize a patented coating which make them water repellent. Splash guards are also available for use in very wet environments. An optional stainless steel junction box is available for corrosive environments.

All of the S2 transmitters are designed to interface with RKI controllers, or with PLC/DCS systems.


Available gases include
– LEL, H2S, CO, PPM H2, and CO2
– Toxic gases include NH3, AsH3, Cl2, ClO2, HCN, & SO2
Infrared sensor for combustibles and CO2
Hydrogen-Specific now available
Patented water repellent sensor coating
4-20 mA output
Explosion proof construction
Optional stainless steel junction box


Petrochemical Plants
Gas Plants
Offshore Drilling Platforms
Water & wastewater treatment plants
Pulp & paper mills
Gas, telephone, & electric utilities
Parking garages
Manufacturing facilities
Chemical storage buildings



General Specifications

Product Specifications
Sensor TypeElectrochemical, infrared, PID
Operating VoltageWire powered (2-wire) 12 to 35 VDC (Optional AC power supply)
Power Draw2 Watts maximum
Protection• Power electromagnetic interference (EMI) filter • 4-20 mA surge suppression • RS-485 surge suppression
Display Screen102 x 64 Resolution graphical LCD screen transflective (sunlight readable) with white LED backlight
Interface3 Push-buttons (MENU, ADD and SUB) 3 Magnetic non-intrusive switches for calibration (MENU, ADD and SUB)
Customizable Settings2 Individually configurable relay set-points
Product add-on Hardware3 Color LED Perimeter Lights and audible alarm, optional. (this option not available with relay option)
Temperature Range-40°C to +70°C
Digital OutputRS-485 modbus Optional 900 MHz or 2.4 GHz radio wireless output
Wired (Analog) Output4-20 mA (3-wire) fault terminal
Product Dimensions5 in. L x 5 in. W x 5 in. H
Total Weight5 lbs.
Enclosure MaterialNEMA Class I, 4, 4X, and 6 polycarbonate enclosure with clear window – IP 66, UL 508 and UL 746C (f1) rated
ConstructionFor use in non hazardous areas only
ControllersCompatible with AirLink 7010, AirLink 7032, Beacon 110, Beacon 200, Beacon 410A, and Beacon 800
Harware Warranty1-Year warranty for electronics and sensor

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