Document 935ZYXmRbkMYdnJm9gBjb26q7

FILE NAME Colonial Sugar Refinery CSR DATE 1966 Mar 31 DOC CSR066 DOCUMENT DESCRIPTION Memo from District Inspector of Mines RE Thermal Precipitator with Inspection Results KALGOORLIE 31st March 66 AJM Senior Inspector of Mincs Mines Department . KALGOORLIE Thermal Precipitator Precipitator In considering the selection of the Thermal Precipitator as a standard instrument for dust collection and assessment I am not detracting in any way from the Watson Victor Konimeter as a general dust sampler for normal field work Although the dust counting efficiency of any Konimeter is admittedly low and is selective with respect to size it is easily recognisable as the most compact and simplest sampling device for quick assessment of dust concentrations in any working place Similarly such an instrument as the Thermal Precipitator Midget Impinger or the Cassella Bexblet could hardly be considered suitable for normal underground dust sampling as they are used mainly for sampling over varying periods of time Actually in the majority of working places where high dust counts have been recorded the fact that conditions were extremely dusty could easily have been assessed without the use of any dust with sampling instrument and I think that this is consiste tn ht e opinion voiced by Drinker & Hatch P. 88 . It has been proved that different sampling instrumente exhibit great variations in their behaviour with different kinds of dust and with particles of different size in the same dust Therefore it appears impossible to determine general conversion factors or to compare instruments on the basis of their absolute efficiencies unless the dust to be sampled is completely homogeneoun To emphasise this point I would like to quote from the I.L.C. Publication Guide to the Prevention and Suppression of Dust 1965 P. 306 of In selecting a sampling system it is first necessary to decide whether it should be based on the weight of dust in the sir or on the mumber of particles which are considered to be in the og dangerous size range . . . Allowance must however be made for the particular characteristics of different sampling instruments and procedures Differences in these respects create difficulties in respect of +90 id /? comparability of results Not only do the different instruments exhibit varying efficiencies in collection but they also have different selectivities with regard to the particles being sampled An example from one series of tests makes this clear Side side sampling with a thermal precipitator and a konimeter was performed operations on the dust created by a series of different underground operations : The following results were obtained : PLAINTIFF'S Bayone EXHIBIT 105240 PENGAD Operation Dust concentration number Thermal Precipitator Konimeter 1 2 3 4 5 6 7 8 9 Y \ 1,230 360 440 490 570 350 210 240 380 - 182 87 103 85 118 89 . 66 . 217 161 X\ \ \, NM \ Lage Lage It will be seen that the health risks of operations 1 and 4 are the greatest according to the thermal precipitator while the kanimeter indicates that operation 8 presente the greatest hazard The ideal instrument is one which will collect a representative sample of the dust as it exists in the environment that is without altering the particles or their distribution in any way and will enable the result to be quickly and easily assessed Lage rn It should sample only the respirable fraction of the dust with the same selectivity as the human respiratory system and provide information over an extended period of time with regard not only to the average concentrations but also to ephemeral fluctuations It must be of simple and rugged construction for use under the conditions found in a mine and automatic operation would be most desirable Although the above points illustrate the optimum requiro- ments in any dust sampling instrument there is however no instrument at present available capable of fulfilling all these ~ requirements Most of them are selective in operation or break up aggregated and give an exaggerated reading of the number of fine particles present Without doubt the choice becomes quite restricted and it generally falls on an instrument which allows a | large mumber of samples to be taken at different places in the shortest possible time or else in a contimous sampling device As I stated before the Konimeter is a suitable sampler for normal routine dust sampling underground and it fulfills several of the previous mentioned requirements viz rugged ; construction large mumber of samples which can be sampled the air volume sampled is fafly large it is of a handy size and once loaded is always ready for sampling In fact I for one consider it the most practical instrument for routine dust sampling -- -- * However it also has great drawbacks the most important being its unpredictable performance or efficiency under varying conditions Similar instruments will give widely different results in the same environment owm w oF It has a tendency to break up aggregates owing to the high impact velocity There is a difficulty in evaluating heavy concentrations conflem . Because of its rapid sampling rate - about 0.1 cents - the samples are only instantaneous values which may differ considerably from the average values Also the quantity of dust collected in the sample depends to a large extent on the nature and thickness of the adhesive film Samples are often crowded out with background count due to bubbles in foreign matter in the adhesive film This phenomena has increased since the use of field illumination and from our u own experience we found it necessary to switch from using Konimeter Jelly to the Petroleum Jelly solution Even so we have received reports on the difficulty caused by excessive background N.S.W. hap resypeted finer finer us finer counts in this solution Department of Hines occasions in the last two years our Petroleum Jelly solution as they were difficulty in overcoming background intrusion resypeted form experiencing w of According to the International Labour Office's Guide to the Prevention and Suppression of Dust in Hining Tunnelling and Quarrying 1965 the Kanimoter is not so suitable for precise dust measurements but it is of value when used in conjunction with other ~ instruments which give more precise information about the nature of the dust concentrations concentrations Sample Precipitator need Precipitator for a more precise instrument such as the Thermal is becoming increasinbly evident each year premimely \.bs, We have a highly technical and qualified staff whose responsibility . lies in the control of dust suppression in all mines quarries reduction and crushing plants throughout the State It is our duty to convince Mine and Company Officials of the need for increased dust control This is not always easy when our sole method of dust sampling is per medium of the Konimeter Dust counts tendered by our Department have on several occasions been queried by some of these Companies on their reliability vapour and foggy atmospheres have sometimes been the cause of discussion on high results Breaking of aggregate concentrations have been other Cambes Until we convinced the Mines to standardise on Field A. Illumination for particle countings differences of opinion arose on whose dust count was correct dark field illumination invariably gave higher readings Various methods for sampling the asbestos dust at Wittenoom . Karble Bar have been tried in conjunction with Konimeter Sampling ande.g. Tyndallascope and Midget no effective results Impinger with The Thermal Precipitator acquired would not be used for routine dust sampling Its main requirements would be to provide a standard for comparison with other instrumenta which would be universally accepted je Provide a precise instrument for carrying out special investigations into any facit of the industry whether surface plant or underground Results from such an instrument would be more acceptable whenever there was any variance of opinion -- C When any place is in doubt due to changing environment 6.g. Primary Crushing operations ore pass control operations areas affected by secondary blasting operations operations in close proximity Mineral Sands Treatment Plants the need for a continuous sampler is multiplied 211 ~ Fe ee | etree sat ge Oe e 8 FA , re c It has been necessary on numerous occasions in the past when investigating anomalous conditions to determine the dust concentrations over a period of time due to changing environment throughout the shift This has applied both surface and underground To carry out such a survey there are a number of points to be determined e.g. the quantities and characteristics of the dust liberated the dustiest operations places and equipment and the variations in dust concentrations in the course of a shift or between abifts The information obtained is necessary to plan effective measures for prevention and suppression of dust in the most efficient manner To carry out such a survey it is necessary to obtain some form of continuous sampler In the past we have obtained the use of a Midget Impinger or a Thermal Precipitator from the School of Mines However this not always convenient for us or the School Although it is agreed that the necessity for obtaining 100 efficiency in dust particle concentrations is not very great and that the main characteristic to be determined is whether or not an industrial hazard exists in certain working places I would like to add that the need for a world use of a standard method of dust determination to serve different countries and Silicosis Conference in Hatch P.131 as a basie of comparison of different industries was South Africa as far back as . conditions in emphasized at the 1930 Drinker ^ There is no doubt that the Thermal Precipitator is fast _ becoming that recognised standard It is also quoted in Drinker & Hatch's publication Industrial Dust P.130 that at the time of publication of this book the Thermal Precipitator had not been used to any extent in industry and that its merits had not been fully explored However it is now regarded as one of the most reliable dust sampling instruments and my be used for sampling all kinds of airborne particles both organic and unorganic at high or low concentrations ~ I.L.O. Guide to the Prevention and Suppression of Dust 1965 P.326 This concludes my views on the subject and although they may appear lengthy in detail I consider that as it is the responsibility of our Department to improve and maintain the standard of ventilation and dust suppression in this State we should use the best means available in this regard Alphe DISTRICT INSPECTOR Vent)