Detector Heads

Detector Heads

M2A Series

Stand Alone Explosion Proof Transmitter


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 LCD 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 and CO2. For CO2, a general purpose (not explosion proof) construction is also available.

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 M2A represents the latest leading edge technology in sensor / transmitters today.

The “A” version of the M2 style instrument includes several improvements over the past design. This includes an OLED display for cold temperature operation (to -40 C or F), side access conduit opening for better leak protection, improved RFI/EMI resistance, and superior protection against power surges or spikes.

S2 Series

Diffusion 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, 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.


Low Cost Transmitter


The RKI low cost CO/H2S transmitter is a highly reliable and very cost effective basic 4-20 mA transmitter for the detection of carbon monoxide and hydrogen sulfide. The electronics are protected inside a plastic enclosure to avoid damage from mechanical abuse, water, dust or corrosion. Sensors for H2S and CO are long life and typically last 2 – 3 years.

The transmitter operates from 24 VDC (11VDC to 30 VDC), and provides a 4-20 mA signal which can be connected to a wide variety of controllers. The low cost CO/H2S can be used either indoors or in semi-enclosed areas.

The only tools required to calibrate the low cost CO/H2S transmitter are a voltmeter, screwdriver, and calibration gas. The zero and calibration functions are performed by adjusting potentiometers on the amplifier board. The amplifier board has test jacks for the connection of a voltmeter for calibration purposes, and the sensor response is viewed on the voltmeter as a 100mV to 500mV signal. Field calibration can be performed easily and quickly by one person.