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Baseefa Ltd

DSEAR & Dust Hazards - Where are we today?

Author : Barry Pomford, Senior Risk Engineer, GexCon UK

08 February 2010

In 2007 I wrote an article for HazardEx titled ‘There’s more to DSEAR than risk assessment’ which discussed the procedures required to gain compliance with DSEAR, three years on it is interesting to review how we have progressed and to consider what has actually been completed by many companies to gain such compliance.

DSEAR & Dust Hazards - Where are we today?
DSEAR & Dust Hazards - Where are we today?

Based on the experiences in the intervening period it has become evident that there are certain commonalities in the approach taken by companies striving to reach a perceived compliance end point and also in the way in which they view the legislation. Not all the companies I have dealt with are clear on what is required of them and in many cases have a very poor understanding of the legislation and the associated science.  Many have not yet started the compliance process at all believing they are “exempt” as they don’t consider that  they use any hazardous materials or processes, however they have no method of demonstrating this to the enforcing authority.  When they do start to look properly at their process they are usually amazed at what they find.

First, let us start by stating what should be the obvious i.e. that (DSEAR, UK) (ATEX 137, Europe) is statutory legislation i.e. SI 2776:2002, Directive 1999/92/EC and compliance is mandatory not optional. 

Many firms still treat this as a low priority, and will only start to consider it when they have the time/inclination/resources and of course when they receive a visit by the enforcing authority and are handed an improvement notice giving them 12 weeks or so to get their house in order.

There is generally a failure to understand the implications of the sanctions that can be levied by the enforcing authority, both on the company and responsible individuals.  In many cases the perceived cost of compliance can be a very real issue, however in reality it costs very little to establish a basis of safety strategy and compliance plan that can be rolled out as finances are available.  This, at the very least, can be seen as a positive move and a willingness to gain compliance within the essence of the law. 

As indicated the perceived cost of compliance can become a barrier to the overall compliance progress.  Often this perceived cost is based on scant information, poor knowledge and sometimes, just bad advice.  What must be remembered is that the object of DSEAR  & ATEX is to ensure the process operation / facility is safe, not necessarily re-engineer it. 

What we are trying to achieve is to ensure that if an incident occurs within the process it does not result in someone getting hurt or injured.  To this end, the role of procedures, work practices and methods as a means of improving safety, tend to be overlooked.  Removing a person from a hazardous area is just one way of ensuring that risks to people are reduced. 

What is often forgotten too, is the potential for secondary explosions, triggered by the primary incident; these can have far reaching effects, be devastating and can result in serious injury to people remote from the primary event.  In general the methods for reducing the potential for these secondary’s is normally straight forward and in many cases does not require huge capital expenditure either.

Incidents of secondary dust explosions within the USA over the last decade have resulted in significant loss of life and has generated several new federal laws to try and reinforce the requirements and guidance that has been in force for many years. More information including some excellent video’s can be viewed from the US Chemical Safety Board. www.csb.gov

To move correctly and efficiently towards the compliance goal requires a detailed understanding of the process and operation and also knowing where you currently stand in relation to the statutory requirements. This starts with an initial measuring activity. In order to achieve this understanding, the process and operation must be assessed and quantified; I refer to this as the measuring process i.e. the “yard stick” by which the current compliance status is assessed.  This takes the form of assessing the type and size of any hazardous zones, based on good sound knowledge of the operation and the specific properties of the materials being used.  A semi-quantitive risk assessment also needs to be completed to consider the probability of an explosive atmosphere, the likelihood of an effective ignition source and the consequence of a primary and secondary event..  These two assessments based on good quality information will not only establish where you currently stand in relation to legislative requirements but will form the basis for the layout of the compliance plan.

It cannot be overstressed at this point that if this measurement process in not completed correctly or is based on poor facts or incomplete / poor material properties, then compliance plans may be produced which could result in either:

 Dangerous operations.

Or

 Expensive changes to the process or equipment.

In either case the desired compliance may not be achieved.

It is very true to say that the quality of the result you achieve from this measurement process is only as good as the quality of the information and knowledge that was put into it.  Since this forms the basis of all future work, it makes sense to put in the time, quality and knowledge to get it right.  This also helps to keep compliance costs down.

One of the many issues that befall companies is that of over zoning or blanket zoning of areas based on a poor understanding of the science of explosions and a lack of knowledge of the properties of the materials being used.  The minimum explosive concentration (MEC) must be reached before a dust cloud will form an explosible atmosphere; a failure to understand this often results in incorrect zoning.  The MEC can vary significantly from powder to powder and it is important to know just how much is needed to make a dust cloud potentially hazardous.  The converse is also true where there is a general failure to recognise the incipient release of fine dust and the hazards associated with this form of release over time.

Having reached the point of establishing the current status of compliance for the operation, experience has shown that this is the point at which many companies stop, believing they have completed what the law requires.  In some cases poor documentation exists, where zones are established but no criteria or justification for their assessment has been given.  This makes life very difficult if taken to task about the validity of a classification or the extent of a zone.  It also makes the subsequent stages of compliance difficult and often results in a complete re-assessment of the zones and by default the risk assessments.

The logic of the situation is that once you have established what the risks and zones are; improvements should be made to eliminate of reduce both.  This process is often overlooked and companies often set out to “deal” with the zones that have been established.  This approach does not necessarily comply with the philosophy of DSEAR and it is a tendency to overwhelm the problem rather than solve it.  This approach is often the more expensive option. A zone reduction exercise should be the next step one takes.

It is more sensible to look at the zones that have been established, identify why they exist, (obviously due to dust clouds or layers) and remove the source of dust that is causing them.  This should reduce the type and the size of the zone and hence the risks associated with them.  It may also reduce the potential for secondary explosions.  However, a smaller zone or one of a less onerous classification will often mean less expenditure on the equipment located within its definition hence reducing the cost of compliance. 

The techniques and methodology used to reduce zone size and classification in a cost effective way varies and in some cases is unique to the plant or process being considered.  Having a good understanding of explosion science is important to this process so that solutions are based on scientific fact and not on such criteria as (an often seen phrase) “anecdotal evidence”.  It is important that all safety systems are fully designed and justified and the same applies for changes to zone classification and extent.

Equipment used within a hazardous area must be suitable for the zone in which it is located and must not represent a viable ignition source to the flammable materials being used in the area.  This can be achieved by selecting new equipment according to the areas ATEX specification, but what about existing equipment?  If none ATEX certified equipment is to continue in use and not to be replaced it must be established, by assessment, that it is safe for such use or made safe by some means.  This applies to both mechanical and electrical equipment.  In order to keep this cost effective, whichever path is taken depends to a large extent on the equipment.  If it is for example an electric motor it may be more cost effective to replace it with an ATEX approved version.  However, if it is a large item of mechanical equipment for example, it may be very expensive to replace and may not be manufactured in an ATEX approved version, in which case assessment/modification may be the only solution.

In this example such assessments would follow the guidance given in the European standards for Non electrical equipment for potentially explosive atmospheres.

To conclude I don’t believe we have made any real progress over the last three years and I strongly believe that there is a failure to appreciate the major hazards presented by flammable dusts in industry and that a major dust explosion incident within the UK could be lurking round the corner.

It is very important to understand that an appreciation of DSEAR / ATEX 137 and the science involved via a short course is not the same as gaining an in depth knowledge of the subject.  Assessments and therefore risks will vary according to the level of knowledge, training, experience and hence competency possessed by the individual completing the tasks. In many large plants and complex cases it may be wise and often prove cost effective to seek advice and assistance from experienced professionals.

This then raises two further questions.

Who is a competent person?
What is a suitable and sufficient risk assessment?

Both questions seem easy to answer but difficult to defend .I will leave that debate for another time.


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