Annual Report,2009 - Directorate General of Mines Safety

DGMS Annual Report, 2009
No. DGMS (Tech)/Circular No./ 14 Dhanbad, Dated – 17.11. 2009
To,
All Owner/Agent/Manager of Underground Coal Mines.
Sub:- Use and care of Local Methane Detectors in Underground Coal Mines.
Of recent, Local Methane Detectors (LMD) are being installed in underground coal
mines for monitoring the make of inflammable gases and for imitating suitable
mitigating measures well in advance before the concentration assumed dangerous
proportions. In this connection, a DGMS (Tech) Circular No. 6 of 2009 was issued to
the industry covering a few aspect of the installation and operation of the LMDs in
the mines.
However, recent inspection of such installation by the officers of this Directorate
revealed that such installation are not in a position to deliver the purpose for which
they were installed, on account of several reason. It was also revealed that the
aforementioned DGMS (Tech) Circular No. 6 of 2009 was also not being followed in
the right spirit.
This matter was viewed on a serious note and a technical workshop was organized in
this Directorate at Dhanbad on the 8 th of September, 2009 for extensive deliberations
on the above subject. As a result of the deliberations, the following recommendations
were arrived at.
1.0 Various components which make an LMD :- An LMD shall include the
following as essential basic components.
A CH 4 sensor unit
An FLP housing for the electrical circuits and a display unit for the detected
and measured CH 4 concentration. The FLP housing may be integrated with the
sensor unit. The FLP housing shall be of an approved type. The FLP housing
shall accommodate various arrangements for battery backup and coupling the
LMD with the power supply system of the ventilating district.
An audio-visual warning alarm unit.
2.0 The defined parameters of the life of the sensor used in the LMDs and their
operating limits in terms of temperature and relative humidity :- The minimum
life of a sensor used in the LMDs shall be at least three years. The sensor shall
operate satisfactorily at a temperature upto 50 0 C and a relative humidity of
upto 100%.
3.0 Place of installation of the LMD :- The LMD shall be installed in the main
district ventilation return airway of the district, as close as practically possible
to a well supported roof as may facilitate clear observation of the display unit.
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