(1)For the purposes of ensuring adequate treatment of coal dust as required under regulations 143 and 144, systematic samples of mine dust shall be collected, tested and analysed at intervals and in the manner specified in this regulation.(2)Every return airway as lies within two hundred meters of the last working face and every haulage, tramming or conveyor roadway which is not naturally wet throughout, shall be divided into zones not longer than one hundred and fifty meters each:Provided that where in a mine some parts are being treated with water and others with incombustible dust, the zones shall be so formed that in each zone only one system of treating coal dust is being followed.(3)Every zone formed under sub-regulation (2) shall be divided into three equal sections, each not exceeding 50 meters in length.(4)Every zone formed under sub-regulation (2) shall be given a distinct number and every section formed under sub-regulation (3), the code letters a, b or c in a systematic manner.(5)The zones and sections, with their numbers and code-letters, shall be clearly marked on a plan prepared on a scale having a representative factor of not less than 2000:1 hereinafter called the "sampling plan", clearly showing the areas of the mine that are naturally wet throughout.(6)Every zone and section shall also be distinctly demarcated in the workings below ground by means of suitable notice boards or by other suitable means.(7)Representative samples of dust shall be collected once in every thirty days from every zone, and for this purpose samples may be collected from different sections such as a, b or c in rotation such that, during every such period of thirty days, all samples are collected from the section a or section b or section c.(8)Representative samples referred to in sub-regulation (7) shall be collected in a systematic manner irrespective of the cleaning and treating operations but shall in no case be collected within a period of twenty-four hours of cleaning and treating of any zone, section or part thereof.(9)If the representative sample of mine dust from any particular zone shows that the provisions of subregulation (3) regulation of 144 have not been complied with, immediate steps shall be taken to clean and treat whole of the zone so as to comply with the provisions of the said regulation.(10)In every travelling roadway, and in every airway other than those specified in sub-regulation (2), samples shall be taken in such a systematic manner and at such intervals not exceeding three months, to maintain proper check on the efficiency of the treatment thereof in terms of sub-regulation (5) of regulation 144.(11)Samples of dust shall be collected from roof, sidesand floor, and shall comprise of dust collected to a depth not exceeding five millimeters on the roof and sides, and to a depth not exceeding 10 millimeters on the floor.(12)Where a zone is treated with incombustible dust, the samples shall be collected by a method of strip sampling, the strips being as near as possible of equal width of not less than 10 centimeters, and at uniform intervals not exceeding five meters.(13)Where a zone is treated with water, the samples shall be collected by a method of "spot sampling" such that a spot-collection of dust is made for every meter of the length sampled, as nearly as possible at regularly spaced intervals along a zigzag path.(14)In collecting the samples, the strips shall be extended into or spot collections made from any cross galleries up to the air-stoppings, if any.(15)Each sample shall be well-mixed and then reduced in bulk (by quartering) to a weight of not less than 30 grams and each sample so reduced shall be packed in a moisture-proof container which shall be suitably labeled or marked.(16)The sampling operations shall be carried out under the supervision of a competent person holding a manager's or overman's certificate or degree or diploma in mining or mining engineering from a university or institution approved for the purpose, who shall be designated as the "Sampling Incharge" and no other duties shall be entrusted to this person except with the previous permission in writing of the Regional Inspector.(17)Within seven days of taking of each sample, it shall be sent for analysis and the result of such analysis, immediately on its receipt, shall be recorded in a bound-paged book kept for the purpose and every entry in this book shall be signed and dated by the sampling incharge and be countersigned and dated by the manager.Explanation. - A place in a mine is considered naturally wet throughout, if it is moist enough to keep the coal dust present, at any time, on the roof, sides and floor and other objects at that place so that it is always combined with not less than 30 per cent. by weight of water in intimate mixture.
