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CTS - M5


The CTS-M5 Series is a microprocessor based transmitter. It uses an Electrochemical gas sensor to detect a variety of gases. Typical applications are enclosed parking facilities, refrigeration rooms and oxygen storage rooms. QEL Engineers, through extensive research and development, have designed the M5  to be an industry leader in performance and application. The M5 offers good value. Standard features within the M5 can only be found as expensive options in other manufacturers' product. A digital display (LCD), push-button programming and on-board meter jacks are all standard. The transmitter provides an analog output of 4-20 mA DC or 2-10 VDC, linear to the measured gas range, for transmission to the Building Automation System (BAS) or controller supplied by others. The signal is fully user assignable over the gas range and can be configured for rising or falling gas concentration. In addition, the RS-485 communications is built in. Input voltages of 24 VDC or 24 VAC with wide tolerances are acceptable. Relay set points may be seen as increasing or decreasing actuation simply by adjusting the deadband relationship. Set the deactuation point above the actuation set point and the M5 will automatically alarm on decreasing concentrations. Relay set points are always present even though the relays themselves are an option. Calibration is very easy - simply apply the calibration gas and adjust the potentiometer to the desired reading on the display. The standard enclosure is a fire retardant Polycarbonate/ABS blend. 


Gas Selection Table

Enlarged Picture

Gas Type # Max. Range
Oxygen - O2 130 0 to 25% v/v
Nitrogen Dioxide - NO2 150 0 to 10 ppm
Carbon Monoxide - CO 160 0 to 250 ppm
Nitric Oxide - NO 190 0 to 200 ppm
Ammonia - NH3 220 0 to 100 ppm


Electrochemical gas sensors are micro-fuel cells designed to be maintenance free and stable for long periods. Gas continuously enters the self-contained cell through a flow limiting diffusion barrier. The Target gas reacts within the electrolyte creating a micro amp current flow between the electrodes. No fluid replenishment is required as these cells are not self-consuming. The cell electrodes degrade with time resulting in a typical working life of 2 to 3 years.

The CTS-M5 transmitter is powered by a nominal 24 V external power supply in a two-wire connection. It transmits a 4-20 mA, 2-10 V, or an RS-485 signal over the calibrated range of the sensor selected. The transmitter is factory configured and calibrated for the sensor selected when ordered as a complete assembly. This universal transmitter accepts any of the listed sensors into a plug-in socket on the board. Calibration is achieved through a simple zero and span adjustment using the appropriate calibration for the sensor installed.


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Last Updated 03/18/10