36
Gas Detection
Gas Sensing Technology Improves Mine Safety
Gas in Mines: an Omnipresent Hazard
An underground mine is an inhospitable place in which to work. Gas poisoning and explosion is a major hazard, with many different types of gas commonly present in mines. Black damp, a mixture of carbon dioxide and nitrogen, is formed as the result of corrosion in enclosed spaces so removing oxygen from the atmosphere and potentially causing suffocation. Fire damp mainly consists of methane, a highly flammable gas that explodes at concentrations between 5% and 15% or, if it does not explode, at 25% concentration it causes asphyxiation. Methane ignition can trigger the much more dangerous coal dust explosions because the shock wave raises coal dust from the floor of the mine galleries to make an explosive mixture that is highly susceptible to spontaneous combustion. Stink damp, so called because of the rotten egg smell of the hydrogen sulphide gas, can explode and is also very toxic. Carbon monoxide, toxic even at low concentrations, is another major hazard.
Without doubt, today’s sophisticated gas detection technology has saved many lives in what is still one of the world’s most dangerous industries.
Gas sensors are the critical operating component of all gas detection instruments. They transform a gaseous concentration, typically measured in ppm, into a change in electrical voltage or current that provides a reliable, stable and repeatable input for the detection instrument. With so many different gaseous hazards potentially present, effective gas detection is critical in protecting life and equipment underground.
Apart from gas-related hazards, underground mining dangers include suffocation, gas poisoning, roof collapse and gas explosions, while open cut hazards are principally mine wall failures and vehicle collisions. Most risks are greatly reduced in modern mines, and multiple fatality incidents are now rare in most parts of the developed world. However, according to the Bureau of Labour Statistics, mining remains the second most dangerous occupation in America, with 30 deaths in a typical year due to mine accidents.
The Beneficial Impact of Modern Technology on Fatality Rates
Author Details: John Warburton
Strategic Marketing Manager City Technology
Walton Road, Portsmouth, PO6 1SZ Tel: + 44 2392 325511 Fax: + 44 2392 386611
Email:
john.warburton@citytech.com Web:
www.citytech.com
Modern technology employed in mines throughout the developed world, has dramatically improved safety. Improvements in mining methods such as automated longwall mining, effective hazardous gas monitoring, gas drainage, better electrical equipment and improved ventilation have reduced many of the risks of rock falls, explosions, and unhealthy air quality. In less developed and developing countries, many more miners continue to die annually, either directly as the result of accidents in mines, or indirectly as the result of illnesses contracted from working under poor conditions. China's coal mining industry is the world’s largest; unfortunately, it also has the worst fatality rate amongst its workers. Thousands of people die every year in the Chinese coal pits, compared with 30 per year in the USA. Coal production in China in 2007 was 2.7 billion tons, 40% of world production and twice that of the US. However, such volumes come at a high human cost. The number of coal miners is around 50 times that of the US, making deaths in coalmines in China 108 times more frequent per unit output than in the US. China has taken significant steps to improve safety in its mines, and although the absolute number of fatalities is still very high when compared to other regions, the number of deaths is on a strong downward trend, despite the dramatic increase in coal production over the recent past.
Gas Sensors Improving Mine Safety
As the world’s leading manufacturer of gas sensors used in personal gas detection equipment, industrial safety systems and residential gas detectors throughout the world, City Technology has made a significant contribution over the years to improved safety in mines. Operating from four main facilities in the UK, Germany, the USA and China, over 300 different sensors, based on electrochemical, pellistor and NDIR (non- dispersive infra-red) technologies, are manufactured. They respond to 28 common and exotic gases with excellent response linearity and high immunity to cross-contaminants. City’s sensors are approved to the demanding specifications issued by the mining industries in emerging regions and the established markets of North America and Europe.
The Challenges Facing Gas Sensor Manufacturers
In deep coalmines, extreme temperature changes, rapid humidity variations and significant pressure changes are experienced as miners travel down from the surface. In both deep and open cast coal mines methane gas is an ever-present hazard. City’s methane and other flammable gas sensors have extensive approvals to the various global mining specifications. Specific regional issues are a further complication, for example, in South African mines, hydrogen cross-sensitivity is a particular concern. One of City’s key strengths is a strong new product development programme, and the most recent product introductions have been specifically designed for mining applications. 4OXV, the latest oxygen sensor, is highly stable under rapid pressure change, and the
AET Annual Buyers’ Guide 2013
www.envirotech-online.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88
