Non Explosion Proof

S2 Series Non Explosion Proof

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, Groups B, C, D). An optional non-explosion proof version is available for oxygen, H2S, CO, and CO2 in non-hazardous atmospheres. 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, SO2, PH3, AsH3, and HCN.

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, SO2, HCN, and more
  • 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
  • Refineries
  • Gas Plants
  • Offshore Drilling Platforms
  • Water & wastewater treatment plants
  • Pulp & paper mills
  • Gas, telephone, & electric utilities
  • Parking garages
  • Manufacturing facilities
  • Steel
  • Automotive
  • Chemical storage buildings
O2 Oxygen H2S Hydrogen Sulfide CO Carbon Monoxide Toxics See chart below CO2 Carbon Dioxide
Part # 65-2320RK 65-2330RK 65-2335RK See chart below 65-2397RK-02 65-2397RK-03 65-2397RK-05 65-2397RK-10  
Sensor Galvanic cell Electrochemical Infrared
Measuring Range 0-25% Vol. 0-100 ppm 0-300 ppm See chart below 0 – 5000 ppm 0 – 5% Vol. 0 – 50% Vol. 0 – 100% Vol.
Lower Detectable Limit (LDL) 0.1% Vol. 2% of full scale
Accuracy (whichever is greater) ± 0.5% O2 ± 5% of reading ± 2 ppm H2S ± 5% of reading ± 5 ppm CO ± 10% of reading or ± 5% of full scale ± 5% of reading or ± 2% of full scale
Response Time (T-90) 20 Seconds 45 Seconds 30 Seconds 60 Seconds 30 Seconds
Max Current Draw (24VDC) 25 mA max, 2 wires 60 mA (power wires) 25 mA (signal wires) 3 wires
Life Expectancy 2 years normal service 2 to 3 years with normal service 5 years plus with normal service
Operating Environment
Location Indoor Class I, Div. 2
Temperature -4°F to 122°F -20°C to 50°C 14°F to 104°F -10°C to 40°C -40°F to 122°F -40°C to 50°C
Humidity 0 – 99% RH non condensing 5-95% RH 0 – 99% RH non condensing
Housing J-Box Cast aluminum, explosion-proof
Sensor Plastic or aluminum
Zero Sets transmitter output to 4 mA with zero output from sensor
Span Sets transmitter output to 20 mA with full scale output from sensor
Operating Voltage 19 VDC to 30 VDC
Output 4-20 mA signal
Controllers Compatible with the following controllers: Beacon 110, Beacon 200, Beacon 410A, and 800, also PLC and DCS systems
Warranty One year materials and workmanship
S2 toxic sensor S2 toxic sensor

Non Explosion Proof Toxic Assemblies

Part Number With J-Box Gas Range Resolution Sensor Type
65-2340RK-NH3 Ammonia (NH3) 0 – 75.0 ppm 0.1 ppm ESM -01
65-2340RK-AsH3 Arsine (AsH3) 0 – 1.50 ppm 0.01 ppm ESM -01
65-2341-CL2 Chlorine (Cl2) 0 – 3.00 ppm 0.01 ppm CT-7
65-2341-CL2-10 Chlorine (Cl2) 0 – 10.0 ppm 0.1 ppm CT-7
65-2341-CLO2 Chlorine Dioxide (ClO2) 0 – 1.00 ppm 0.01 ppm CT-7
65-2340RK-HCN Hydrogen Cyanide (HCN) 0 – 15.0 ppm 0.1 ppm ESM -01
65-2340RK-PH3 Phosphine (PH3) 0 – 1.00 ppm 0.01 ppm ESM -01
65-2340RK-SO2 Sulfur Dioxide (SO2) 0 – 6.00 ppm 0.01 ppm ESM -01
* Partial pressure sensor for helium (He) applications. Consult factory for details.

S2 Wiring Matrix

S2 Transmitter
Number of Wires to Controller
Maximum Distance to Controller
Beacon 410 Configuration============
18 AWG wire
16 AWG wire
14 AWG wire
LEL / IR / CO2
2500 ft.
5,000 ft.
8,000 ft.
2500 ft.
5,000 ft.
8,000 ft.
2500 ft.
5,000 ft.
8,000 ft.
2500 ft.
5,000 ft.
8,000 ft.
2500 ft.
5,000 ft.
8,000 ft.
Specifications subject to change without notice.