Explosives Britain

In Great Britain the COSHH Regulations cover virtually all substances hazardous to health. (Excluded are asbestos, lead, materials dangerous solely due to their radioactive, explosive, or flammable properties, or solely because of high or low temperatures or pressures, or where risk... 

The original steam generators were simple pressure vessels that were prone to caiasirophic failures and loss of life. Due to better boiler design, tube-fired boilers, and boiler inspections, the incidence of catastrophic failure is now to a rare event (about once every 100,000 vessel-years). In Great Britain in 1866, there were 74 steam boiler explosions causing 77 deaths. This was reduced to 17 explo.sions and 8 deaths in 1900 as a result of inspections performed by the Manchester Steam User Association. In the United States, the American Society of Mechanical Engineers established the ASME Pressure Ves.sel Codes with comparable reductions. 

Surveying the situation realistically, Perkin retired from the fray. He was tired of litigation, fires, and explosions, and he could see that Britain was losing the chemical race to Germany. Even Professor Hofmann had left England and gone home. At the age of 35, Perkin was already a millionaire, so, in 1873, he renounced manufacturing to return to the scientific research he had loved in his youth. 

It is essential in explosive operations to avoid the presence of grit or extraneous materials. In Britain the general practice is to provide buildings with clean floors, which can only be approached by the donning of special shoes or overshoes. The carrying in of unnecessary objects and particularly ferrous tools is strictly forbidden, and, of course, the presence of matches or smoking materials is illegal. 

It will, therefore, be seen that the best and safest practice is to use in each situation in the coal mine an explosive which is best adapted for the operation in hand. The use of unnecessarily weak explosives, even though apparently safer in some tests, is often a disadvantage and can be dangerous. These considerations have led to the development of a series of types of explosives suited for particular purposes in coal mines and subjected to tests relevant to their individual uses. Thus, in Britain there are now five classes of permitted explosives. In Germany there are three classes. In the U.S.A. geological conditions are different and the hazards are less than in Europe, and it has been possible to work throughout with the strongest types of permissible explosives. 

These explosives, when introduced into Britain, were called equivalent to sheathed or Eq.S. explosives. Currently, the explosives must pass the following tests ... 

In the other method, particularly popular in Germany, the ammonium nitrate is replaced by an equimolar mixture of ammonium chloride and potassium or sodium nitrate. The reaction between the salts, which gives potassium or sodium chloride and ammonium nitrate or its decomposition products, is relatively slow and does not occur to a marked extent when the explosive is fired in an unconfined condition. This method of working is particularly effective in reducing the power of an explosive in the unconfined condition. Used alone it has not proved popular in Britain, because of the low power which tends to be developed under practical firing conditions. Moreover, the finely divided sodium chloride smoke which is produced by the explosive tends to be unpleasant for the miners. 

The most recent practice in Britain is to employ a combination of the above methods so as to give the required overall effect on the power of an explosive in an unconfined condition. Compositions and properties of such an explosive are given in Table 7.3. 

Another hazard is that cartridges fired early will cause compression in other holes and thus desensitise the explosive. To overcome this a sensitive explosive is required and one of semi-gelatine type is used in Britain. 

As Britain is relatively poor in mineral deposits, this type of mining is less important here than in other countries of the world. The gold mines in South Africa, metal mines in the U.S.A., Canada and Sweden all use considerable amounts of explosive. In such mines the methods of working are often appreciably different from those described above and adapted to very large-scale production. 

For civilian aircraft the facility for rapid starting is not important and cartridge operation is not often employed, particularly because it involves storing and handling explosives, even though the hazards of these explosives are those of fire and not of detonation. For military purposes, however, particularly for fighter aircraft which are best scattered on an airfield, a rapid start is of considerable importance. Therefore cartridge operated starters are much used for these aeroplanes. In Britain, development has been essentially with propellants based on ballistite, namely double base propellants of the solventless type, whereas in the United States composite propellants based on ammonium nitrate have proved more popular. 

Heat Test A rapid stability test depending on detection of traces of products of decomposition of an explosive at an elevated temperature. In Britain this usually refers to the Abel Heat Test. 

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