Name: S2 Series – Gas Sensor/Transmitter
Brand: RKI Instruments

Overview

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.

Related Services

Fixed Systems Turnkey Solutions

Design, Consultations, and Engineering
Installation
Start-up
Training
System Maintenance

Application

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

Explosion Proof Specifications

Explosion Proof – Class I, Div. 1 , Groups B, C, D

	LEL General Purpose	LEL H2 Specific	H2 PPM Hydrogen MOS	O2 Oxygen	H2S Hydrogen Sulfide	CO Carbon Monoxide	CH4 Methane IR	HC Hydrocarbons IR	CO2 Carbon Dioxide IR
Part #	65-2405RK	65-2451RK	65-2445-100 65-2445-500 65-2445-1000 65-2445-2000	65-2322RK	65-2331RK	65-2336RK	65-2394RK-CH4	65-2394RK-HC	65-2396RK-02 65-2396RK-03 65-2396RK-05 65-2396RK-10
	65-2405RK-05	65-2451RK-05
Sensor	Catalytic		Metal oxide semiconductor	Galvanic Cell	Electrochemical		Infrared
Measuring Range	0-100% LEL	0-100% LEL (H2 Specific)	0-100 ppm 0-500 ppm 0-1000 ppm 0-2000 ppm	0-25% Vol.	0-100 ppm	0-300 ppm	0-100% LEL		0 – 5000 ppm 0 – 5% Vol. 0 – 50% Vol. 0 – 100% Vol.
Lower Detectable Limit (LDL)	2% of full scale			0.1% Vol.	2% of full scale
Accuracy (whichever is greater)	± 5% of reading or ± 2% LEL		± 10% of full scale	±0.5% O2	± 5% of reading ± 2 ppm H2S	± 5% of reading ± 5 ppm CO	± 5% of reading or ± 2% of full scale
Response Time (T-90)	30 Seconds	20 Seconds	45 Seconds	90 Seconds	60 Seconds	90 Seconds	30 Seconds
Max Current Draw (24VDC)	70 mA (power wires) 25 mA (signal wires) 3 wires			25 mA max, 2 wires			60 mA (power wires) 25 mA (signal wires) 3 wires
Life Expectancy	2 to 3 years with normal exposure to flammable gas	3-5 years with normal service	5 years plus with normal service	2-3 years with normal service			5 years plus with normal service
Operating Environment
Location	Indoor or outdoor. Explosion proof for Class I, Div. 1, Groups B, C, and D.
Temperature	-40°F to 167°F -40°C to 75°C		-4°F to 104°F -20°C to 40°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
Humidity	0 – 99% RH, non condensing
Housing
Housing J Box	Cast aluminum explosion proof, optional stainless steel J-box available
Sensor	Stainless steel explosion proof
Controls
Zero	Sets transmitter output to 4 mA with zero output from sensor
Span	Sets transmitter output to proper level when span gas is applied
Output	4 – 20 mA signal
Operating Voltage	11 VDC to 30 VDC		19 VDC to 30 VDC	19-30VDC (250 OHMS impedance max)			11 VDC to 30 VDC
Approvals	65-2405RK UL	65-2451RK UL	65-2445-100 65-2445-500 65-2445-1000 65-2445-2000 UL	CSA NRTL			C UL US
	65-2405RK-05 CSA	65-2451RK-05 CSA	65-2445-100-05 65-2445-500-05 65-2445-1000-05 65-2445-2000-05 CSA
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

Toxic Gas Specifications

Toxic Gas Transmitters – Class I, Div. 2

	O2 Oxygen	H2S Hydrogen Sulfide	CO Carbon Monoxide	Toxics See chart below	CO2 Carbon Dioxide
Part #	65-2320RK 65-2321RK	65-2330RK	65-2335RK	See chart below	65-2397RK-02 65-2397RK-03 65-2397RK-05 65-2397RK-10
Sensor	Partial Pressure 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
Housing J-Box	Cast aluminum, explosion-proof
Sensor	Plastic or aluminum
Controls
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 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
65-2341-NH3-75	Ammonia (NH3)	0 – 75.0 ppm	0.1 ppm	CT-7
65-2341-NH3-1	Ammonia (NH3)	0 – 100 ppm	1 ppm	CT-7
65-2341-NH3-2	Ammonia (NH3)	0 – 200 ppm	1 ppm	CT-7
65-2341-NH3-5	Ammonia (NH3)	0 – 500 ppm	1 ppm	CT-7
65-2340RK-AsH3	Arsine (AsH3)	0 – 1.50 ppm	0.01 ppm	ESM -01
65-2341-CL2-3	Chlorine (Cl2)	0 – 3.00 ppm	0.01 ppm	CT-7
65-2341-CL2-05	Chlorine (Cl2)	0 – 5.00 ppm	0.02 ppm	CT-7
65-2341-CL2-10	Chlorine (Cl2)	0 – 10.0 ppm	0.1 ppm	CT-7
65-2341-CLO2-1	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-NO2	Nitrogen Dioxide (NO2)	0 – 15.0 ppm	0.1 ppm	CT-7
65-2340RK-SO2	Sulfur Dioxide (SO2)	0 – 6.00 ppm	0.01 ppm	ESM -01

S2 Wiring Matrix
S2 Transmitter	Number of Wires to Controller	Maximum Distance to Controller
S2 Transmitter	Number of Wires to Controller	18 AWG wire	16 AWG wire	14 AWG wire
LEL / IR / CO2	3	2500 ft.	5,000 ft.	8,000 ft.
Oxygen	2	2500 ft.	5,000 ft.	8,000 ft.
H2S	2	2500 ft.	5,000 ft.	8,000 ft.
CO	2	2500 ft.	5,000 ft.	8,000 ft.
Toxics	2	2500 ft.	5,000 ft.	8,000 ft.