Current affairs Fires were still burning and very little of
the structure was identifiable, but even then the urban search and rescue team from Merseyside Fire and Rescue Service remained, to continue looking for the body of the one person who was, officially, still only missing. After an extensive investigation by Cheshire
Constabulary and HSE, Wood Treatment Ltd was charged with corporate manslaughter in November 2019. The company’s managing director, George Boden, was charged with manslaughter owing to negligence, while two other managers were charged with breaches of health and safety laws. Their trial began in December 2019. The explosion resulted in a 1,000oC inferno that burned for days, before the bodies of the victims were recovered from the wreckage of the mill buildings. The mill dominated the Cheshire village of Bosley, with many local residents working at the plant. In a statement, the Crown Prosecution
Service said: ‘The company, Mr Boden, and two others who were managers for the company, have also been charged with health and safety offences. These decisions were made following a careful review of all of the evidence presented to us by Cheshire Police as a result of their lengthy and complex joint investigation with the [HSE].’
appropriate safety factors. When assessing the area of spread of gas or vapour before dilution to below its LEL, expert advice should be sought (source: BS EN 60079-10-1: 2009: Explosive atmospheres. Classification of areas. Explosive gas atmospheres). An outline of the zone classifications for dust atmospheres is as follows: • zone 20 – a place in which an explosive dust atmosphere, in the form of a cloud of dust in air, is present continuously, or for long periods or frequency
• the extent of zone 20 includes the inside of ducts, producing and handling equipment in which explosive dust atmospheres are present continuously, for long periods, or frequently
• if an explosive dust atmosphere outside dust containment is continuously present, a zone 20 classification is required
• zone 21 – a place in which an explosive dust atmosphere, in the form of a cloud of dust in air, is likely to occur in normal operation occasionally
(Source: BS EN 60079-10-2: 2009: Explosive atmospheres. Classification of areas. Combustible dust atmospheres.)
Plan of zone precautions
Once zoning of the hazardous areas has been completed, a suitable plan indicating the boundary of each zone should be created. This can be used by the relevant person to ensure all safety precautions relating to the hazardous zones are applied, such as categories of equipment permissible in those defined areas. An example of zoning diagrams from BS EN 60079-10-1 and BS EN 60079-10-2 is provided in Figures 3 and 4 (see p50). Special precautions need to be taken
the requirements relating to hazardous area classification, which are as follows for gases and liquid vapours: • zone 0 – an area in which an explosive gas atmosphere is present continuously or for long periods or frequently
• zone 1 – an area in which an explosive gas atmosphere is likely to occur in normal operation occasionally
• zone 2 – an area in which an explosive gas atmosphere is not likely to occur in normal operation but, if it does occur, will persist for a short period only
The extent of zones depends on the estimated or calculated distance over which an explosive atmosphere exists; this is before it disperses to a concentration in air below its LEL with an
in hazardous areas to prevent equipment from potentially becoming a source of ignition. Where an explosive atmosphere is likely to occur, reliance is placed on using equipment which has a low probability of creating a source of ignition. Where the likelihood of an explosive atmosphere occurring is reduced, equipment constructed to a less rigorous standard may be used. Equipment is categorised as 1, 2 or 3, depending on the level of zone in which it is intended to be used. Several ways of constructing equipment to
prevent ignition risks have been published in harmonised European Standards and, in some cases, additional requirements are set out in the standards relating to installation and use. It is important to understand that it would normally be expected that equipment used in zoned areas would comply with the requirements in the DTI regulations, and that equipment of a
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