NO: MSE-29022|62509|2025|MSE(HQ)

Dhanbad, Date: 08/10/2025

DGMS APPROVAL NO.-MSE_62509/2

From

Director General of Mines Safety
Directorate General of Mines Safety,
P.O & Distt: Dhanbad - 826 016.

To

AVINASH LOHIA, Vishwa Microprocessors Pvt. Ltd, 62 A HAZRA ROAD
West Bengal, Kolkata, KOLKATA, 700019

Subject: Approval under Regulation 208 (3) of the Coal Mines Regulations, 2017, of Environmental Monitoring System with Programmable Sensor Controller TX-9042 Single Port Repeater TX-2122.56 and Multi Port Repeater TX-2122.57 along with Single Port isolator TX-2121 manufactured by M/s Trolex, UK.

Sir,

Please refer to your letter No. VMPL/DB/DGMS/ETS/Renewal/2025-26/079, dated 22.08.2025 and online application ID - 62509, dated 22.08.2025 on the above subject.

In view of satisfactory performance reports from the mines, I, in exercise of powers conferred on the Chief Inspector of Mines also designated as Director General of Mines Safety, under Regulation 208 (3) of the Coal Mines Regulations, 2017, hereby grant the approval of Environmental Monitoring System with Programmable Sensor Controller TX-9042 Single Port Repeater TX-2122.56 and Multi Port Repeater TX-2122.57 along with Single Port isolator TX-2121 manufactured by M/s Trolex, UK.

The Approval is subjected to following conditions:

1. All the conditions of the approval granted vide this Directorate’s letter No. 445/204/EHQ, Dated-04.04.1995, Letter No. 16(7)98-Genl/462, dated 27.03.1998, subject to the conditions stipulated in this Directorate’s letter No. S-66021/27/2006-Genl/3376, dated 11.11.2011 read with letter No. 16(7)98-Genl/1332 dated 26.04.1999 shall remain applicable along with other conditions mentioned in this approval.
2. The Programmable Sensor Controller TX-9042, Single Port Repeater TX-2122.56 and Multi Port Repeater TX-2122.57 along with Single Port Isolator TX-2121 fitted with the Sensors and Systems of Environmental Monitoring System shall be identical in construction to the submitted drawing along with your application and those tested at CSIR-CIMFR and CSA Group testing UK Ltd, UK.
3. The following sensors and equipment—Flammable Gas Sensor (Model TX3261), Toxic Gas Sensor (Model TX3241), Oxygen sensor(Model TX 3264), Temperature Sensor (Model TX2068), Display Unit (Model TX3282), Vortex Gas Flow Sensor (Model TX1321), Single Port Isolator (Model TX2121), Single/Multi Port Isolator (Model TX2122), FLP-Supply (Model TX5172) , Xenon Flashing Beacon (Model TX5331, IS-A105N) i.e. Audio-visual alarm, have been tested by CSIR-CIMFR and Programmable Sensor Controller (Model TX9042) tested from SGS UK Limited as applicable, and found compliant with the latest IS/IEC standards.
4. The display units of the telemonitoring system shall be provided at the surface and also in the underground installations at the Programmable Sensor Controller TX- 9042, Single Port Repeater TX-2122.56 and Multi Port Repeater TX-2122.57 along with Single Port Isolator TX-2121.
5. The Environmental Monitoring system shall consist of the following basic components:

a) Various sensors. i.e. Flammable Gas Sensor, Toxic Gas Sensor, oxygen sensor, Temperature sensor, Vortex Gas Flow Sensor, programable sensor controller.

b) A display unit

c) Programmable Sensor Controller

d) Audio Visual warning device.

e) Surface monitoring system for display, storage and retrieval of readings and also a warning system.

f) Power supply system.

g) Electrical Power tripping arrangements.

h) Connected data transmission cables.

6. The relevant provisions of the Central Electricity Authority, 2023 shall be complied with in all matters relating to the installation, Operation and maintenance of the equipment.
7. Any replacement part required for maintenance of the equipment which is directly or indirectly connected to the FLP/IS features thereof shall be supplied by the manufacturer as and when required.
8. The display shall be clearly visible from a reasonable distance. The display system shall also be provided with a colour changing/blinking arrangement for indicating any recording of an environmental parameter above the pre-set value.
9. The various parameters of the sensors used with the telemonitoring system as regards (a) minimum operating life of sensors, (b) working limits of temperature & relative humidity, (c) calibration including the maximum permissible deviation when tested with standard gases, frequency of calibration, availability of standard gases and various records to be maintained thereof, shall be as follows:

a) The minimum operating life of the sensors shall be as follows:

Sensor Type                      Operating Life

CH4 (Infrared)                   5 years

CH4 (Catalytic)                  2 years

CO                                    2 years

O2                                    1 year

Temperature                     5 Years

Air Velocity                       5 Years

b) Working limits of the sensor in terms of temperature. – Up to 50° C.

              Working limits of the sensor in terms of Relative Humidity – Up to 100%

c) Calibration

(i) The deviation of the measured gas concentration shall not be more than 3% for all sensor types when tested with standard gases.

(ii) The maximum interval of calibration of the sensors shall not exceed three months, alternating between the manufacturer and the user. However, the manufacturer shall examine the complete telemonitoring system in totality at least once in every six months.

(iii) Adequate samples of standard gases shall be always made available at the concerned mine.

(iv) Proper records of calibrations done, duly signed by the designated officer and the Manager for the purpose, shall be maintained at the mine.

10. Any sale/purchase of the continuous telemonitoring system shall be in conformity with the approved system in respect of all the basic components as mentioned above.
11. All technical assistance shall be rendered by the supplier at the of initial installation of the machine in underground. The supplier shall also maintain contact with the user to get themselves apprised of any difficulty that may be faced by the user in the of use, maintenance and operation of the machine.
12. Every customer shall be provided at the time of delivery of the equipment referred to above with

(i). a copy of the factory test report of the particular equipment bearing the particulars and serial number of the same;

(ii). a certified copy of the letter of approval granted by the concerned approving authority of the country of origin for the use of the equipment in gassy coal mines;

(iii). an instruction manual on the maintenance, handling, installation and operation of the equipment; and

(iv). a copy of this letter from this Directorate.

13. The minimum required power back-up with the telemonitoring system in the event of disruption of the main electrical power supply shall be for a period of four hours.
14. The minimum intensity of the audio part of the audio-visual alarm provided with the telemonitoring system shall be 90 dB(A) or higher than the surrounding noise level, so that it can be heard distinctly. In the underground workings, at least one audio alarm shall be provided with every PSC controller of the telemonitoring system.
15. The Suitable electrical interlocking with the electrical power supply system of the area in the mine where the above product is installed, shall be established so as to ensure that the electrical power supply is automatically cut off whenever the % of methane gas exceed 0.75 in the general body of the return airway of any ventilating district or 1.25 in any place in the mine.
16. Every telemonitoring installation shall be provided with an arrangement for recording and retrieving data on a continuous basis for minimum of 30days.
17. Any accident, injuries including loss of lives or properties caused due to defects or malfunctioning of this. product shall be adequately indemnified by the manufacturer in agreement with the user(s).
18. An Officer of this Directorate may also, at any time cause samples of the system to be retested in any approved laboratory/test house at the manufacturer's cost.
19. The approval shall remain valid till the manufacturer has a valid QAN & QAR certification.
20. Further renewal of the approval can be sought through online application at least 90 days prior to the expiry of the validity.
21. The product shall be tested at any Govt./Govt. Approved laboratory whenever standard of testing regime changes and the approval is revalidated from this Directorate under new/revised testing standard (s).
22. Please note that the approval is also subject to the following additional conditions:

a) If at any time, any of the conditions subject to which this approval has been granted is not complied with, the approval shall be deemed to have been revoked with immediate effect.

b) This approval may be amended or withdraw at any time if considered necessary in the interest of safety.

c) This is being issued without prejudice to any other provisions of law that may be or become applicable at any time.

23. The renewal of the approval shall be valid for the period of 05 years i.e. up to 31.08.2030.