M Series Low Cost Transmitter

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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.

  • Water/dust resistant housing
  • Available for H2S and CO
  • Long life sensors (2 + years typical)
  • Competitively priced
  • Compact design
  • Water & wastewater treatment plants
  • Pulp & paper mills
  • Gas, telephone & electric utilities
  • Parking garages
  • Manufacturing facilities
  • Loading docks
Part #H2S
Min Operating
11 VDC
Max Operating
30 VDC
Max Current
25 mA
(2 wire system)
Signal Output4 mA at 0 ppm H2S
20 mA at 100 ppm H2S
4 mA at 0 ppm CO
20 mA at 300 ppm CO
20 seconds to 90%
of concentration
45 seconds to 90% of concentration
Operating Environment

Indoors or semi-enclosed areas
Temperature0 to 120° F

0 – 99% RH,
non condensing

Plastic, water / dust resistant enclosure
2.5″ W x 4.0″ H x 1.5″ D

Life Expectancy2 years normal service when intermittently exposed to H2S2 to 3 years normal service
ZeroSets transmitter output to 4 mA with zero output from H2S sensorSets transmitter output to 4 mA with zero output from CO sensor
SpanSets transmitter output to 20 mA with 100 ppm output from H2S sensorSets transmitter output to 20 mA with 300 ppm output from CO
Tools Needed

Screwdriver and voltmeter used to make adjustments

* Specifications subject to change without notice.
Made in the USA