MONIMET CH4-Monitor
Monimet 
CH4-Sensor/Transmitter Type GMm 01.02.xxx
CH4-Monitor Type GMm 01.02.xxx
I M1 Ex ia I Ma- Measuring range 0.0...100.0 vol % CH4
- Thermal conductivity sensor with gas diffusion entry
- Increased accuracy by compensation of prevailing humidity and temperature by microcontroller (patented)
- Special housing suited to the working conditions in mines and industry. Steel hanger for the suspension, screw threads on the backside optional
- Illuminated four-digit display
- Data processing by microcontroller system
- Output range of the output signal is variable
- Adjustments or status enquiries by means of a press button unit or a magnetic pointer. The housing need not be opened
- Code lock to prevent unauthorized manipulation (can be switched off)
- Fault self diagnosis with alpha numeric display
- Test of the output signal by simulated CH4 values
- Choice between normed analog or digital output signals (optional)
- Two built-in limit switches with optocouplers or relays in the monitor
- Sensor can be replaced on site
- Housing protection rating IP65, sensor protection rating IP 52
The economical, permanently installed CH4-Sensor/transmitter and CH4-Monitor are characterised by their stable measurements, simple and secure operation, robustness and compact construction.
These devices conform to the explosion protection rating of intrinsic safety „i“, catagory I M1 Ex ia I Ma. This means that this device can be used in the zone M1 of underground mines, even when unpermitted high concentrations of the methane gas are prevailing.
This certification conforms to the ATEX directive 94/9/EG for devices and protective systems permitted for use in areas endangered by explosions.
The CH4-Monitor differs from the CH4-Sensor/transmitter because of an additional limit value unit which is equipped with optocouplers or relays.
The measurement of the methane concentration in the sensor block is by means of an thermal conductivity sensor. The gas diffuses into the measuring chamber through a sinter metal disc. To increase the measurement accuracy a microcontroller continously compensates the prevailing temperature and humidity values. A primary filter, which can be easily replaced, protects the sinter metal against dirt. The test gases can be fed into the measurement chamber by means of a plug-on adapter of the type PGA 3.
The operation of the device is very simple: The operator places a small magnetic press button unit on the device. The housing need not be opened. As an alternative he can also use a magnetic pointer. A four digit code which can be entered initially, protects against unauthorized changing of the set values. A self monitoring microcontroller system not only processes the measurement values precisely, it also carries out the operator specific instructions such as the entry of the code, signal instructions and messages, analog and digital outputs and test functions etc. A four digit back lit graphic display shows the measured values in 12 mm high digits.
These devices are protected against shocks, dust and humidity by a cast metal housing (impact strength 20 Joule) and are to be connected by means of a plug-in connector. The sensor block with the CH4-sensor is attached on the lower side of the housing and it can be replaced easily on the underground site.
A steel hanger is attached for the suspension of the device. For a rigid mounting, the device can be provided with thread holes on its rear (extra charge).
