MWS 903

Multi-Channel Gas Warning System
MWS 903


The multi-channel gas warning equipment ADOS MWS 903 continuously monitors the surrounding air and provides an early warning of dangerous, explosive and non-combustible gases and vapours.
It is possible to connect up to 8 gas transmitters (2- or 3-wire) to the unit.

Fields of Application

Monitoring of:

  • Heating systems
  • Garages and tunnels
  • Liquid gas storage rooms
  • Laboratories
  • Cold-storage houses
  • Plastic processing plants
  • Chemical industries
  • Paint manufacturing plants
  • Concentration measurement of O2
  • and many more


  • 6-section keybord and illuminated 4-line LC-Display for indicating actual values, half-hourly average values and fault messages, all clear text encoded
  • Ready, fault and gas warning display
  • Menu-assisted settings for the equipment parameters, via 6-section keyboard
  • Two alarm thresholds for each sensor, independently adjustable from 5 % to 100 % of the measurement range; facility for forming half-hourly average value
  • A maximum of 12 floating alarm outputs for controlling extra warning and control devices
  • Floating change-over contacts for fault, siren and warning banners
  • Serial interface output, RS 232 for connecting a printer or PC
  • Plastic, wall-mounted housing (IP 54)
  • 4–20 mA interface
  • Plastic, wall-mounted housing
  • High operational reliability
  • Low current consumption
  • Easy installation
  • USP unit available

Examples of measurable gases

Gas Formula
Acetylene C2H2
Ether C4H10O
Alcohol e.g. C2H6O
Ammonia NH3
Butane C4H10
Chloroform CHCl3
Hydrogen chloride HCl
Helium He
Carbon dioxide CO2
Carbon monoxide CO
Methane (natural gas) CH4
Neon Ne
Propane C3H8
Oxygen O2
Carbon tetrachloride CCl4
Toluene C7H8
Hydrogen H2
Xylene C8H10

Technical Data

Sensor inputs: 8 two-or-three-wire sensors
(e.g. LCTR 903) with current interface,
4–20 mA
Sensor supply: 24 V= / 200 mA
Ranges: CO 0-300 ppm
NO2 0-30 ppm
CH4 0-100 % UEG
CO2 0-10 Vol %
other ranges on request
Ambient temperature: -10 °C to +40 °C
Digital inputs: 1 input for siren cancel
Digital outputs: max. 12 alarms
1 fault relay
1 siren relay
Warning banner relay
All outputs have floating change-over contacts, max. rating 250 V / 4 A
Standard output signals: Analog output 4–20 mA serial interface RS 232
Mains connection: 230 V / 50 Hz
115 V / 60 Hz (optional)
24 V / DC (optional)
Dimensions (WxHxD): 240 x 160 x 90 mm
Weight: approx. 2 kg
Protection type: IP 54 according to DIN 40050


Signal horn (siren), Warning light, Warning banner, Test meters, Plotter, Stand-by power supply UPS 2000 24 V.

Additional accessories will be offered, according to the system required. An early warning of dangerous, explosive and non-combustible gases and vapours.