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Explosive Atmospheres

What is an explosive atmosphere?

Lighting for ATEX environments

The requirement for effective lighting in areas with explosive atmospheres can on occasion be underrated. If anything, due to the high-risk nature of the work, the lighting needs to be even more efficient than for normal poorly lit areas. This has to be balanced with the need for safety and ensuring the lamp does not and cannot become a source of ignition within the explosive atmosphere.

The following should be considered when deciding on which type of light to use.

There are many records of accidents and incidents where lamps have been found to be the ignitions source causing severe burns and fatalities. Lamps for use in potentially explosive atmospheres must be maintained as required by the manufacturer and used carefully to ensure that the risk of them being damaged while in use in a potentially explosive atmosphere is minimised and preferably eliminated.

Selection of lamps

Great care must be taken when selecting lamps for use in potentially explosive atmospheres. (Refer to BS EN 60079-14 electrical apparatus for explosive gas atmospheres. Electrical installation in hazardous areas).

The lamp should be carefully checked and tested by a suitably competent person for any sign of damage prior to use. The lamp should be checked again prior to storage to ensure that no damage has been done while the lamp has been in use – to prevent the temptation to use a damaged lamp when it is next needed for an urgent repair. The lamp should be carefully stored to ensure it is protected from damage.

Ensure you have a full understanding of the hazards and the risks in the work area. Carry out an effective risk assessment and use a lamp that will provide sufficient light to assist in making the working environment safe but will reduce the risk of it becoming and ignition source to an acceptable (low) level. Once you have decided on the correct lamp for your circumstances ensure it is used, maintained and tested as required.

An explosive atmosphere is a mixture of a dangerous substance or substances (gas, mist, dust or vapour) mixed with air (oxygen), which has the potential to catch fire or explode.

There are obvious workplaces where you would expect explosive atmospheres to be found (and controlled) such as: coal mines, oil rigs, gas rigs, and refineries. Unfortunately, however, explosive atmospheres can also be found in nearly every workplace. For example, they can be found in work areas that utilise such things as solvents, paints, varnishes, flammable gases, liquefied petroleum gas (LPG), dusts produced from operations, and from foodstuffs – just remember the 2015 flour mill explosion in the Manchester area.

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The effect of an explosive atmosphere?

An explosive atmosphere is an atmosphere in a workplace that could, if not properly controlled, cause harm to employees and others as a result of a fire, explosion or similar incident.

An explosion or fire can have a very serious impact on a business’s ability to continue to operate due to loss of premises and equipment.

It can also have very serious consequences for a business’s reputation. Which can have a knockon effect on investor confidence.

Regulations

In the UK, the relevant regulations are the “Dangerous Substances and Explosive Atmospheres Regulations” commonly known as DSEAR.

ATEX requirements

Controls must be applied when work activities involve an atmosphere or a substance being present in the workplace with the ability or potential to create an explosive atmosphere.

To expand on the workplaces that could be affected they will include the following:

  • Storage and use of flammable liquidbased paints and inks
  • Storage and use of LPG
  • Storage and use of oxygen (increases the flammability of other substances)
  • Storage and transport of powders in pharmaceutical and food industries
  • Storage and display of flammable goods (paints in shops)
  • Handling and storage of flammable waste solvents
  • Welding or other ‘hot work’ on or in tanks and drums (confined space) that have contained flammable material
  • Use of flammable gases, such as acetylene, for welding
  • Use of flammable solvents in laboratories
  • Transport of flammable substances in containers around a workplace
  • Deliveries from road tankers containing flammable liquids and gases
  • Bulk storage of powders
  • Chemical manufacturing, processing and warehousing * Note: this is not an endless list – risk assess.

Control the risk

Firstly, you should assess and eliminate the risks of an explosive atmosphere occurring.

If elimination of the risk of an explosive atmosphere being present is not possible due to the work process, then you should ensure you have effective controls in place to reduce the risk to an acceptable (safe) level.

How to assess the risks

Carry out a risk assessment as follows:

Step 1
Identify all, even potential, fire and explosion hazards in the workplace.

This should be a thorough identification and a very careful examination of:

  • All the flammable and explosive substances, gases and liquids etc. present and potentially present (those formed as part of the work process)
  • The potential sources of ignition
  • The activities being carried out in the workplace that could have an impact on the explosive risk
  • The scale of the effects from the fire and explosion

Supplier’s Material Safety Data Sheet (MSDS) should be referred to for information on the properties and hazards of any dangerous substances being used in the workplace. These MSDS’s also provide information on the safe methods for the storage, use and handling of the dangerous substance, or will provide a reference to where this may be found (normally online).

Step 2
Decide who might be harmed and how.

Identify the employees and others at risk from the fire or explosion hazard. Based on your assessment of the risk from the explosion, determine who it might potentially harm. This includes members of the public, on or off site, who might be put at risk by the work activity.

Step 3
Evaluate the risks and decide on precautions.

You should determine whether the control measures being put in place are sufficient to eliminate (always preferable) or reduce the risks of an explosion taking place to a level that meets the legal and business requirements (acceptable risk).

This should take account of such things as the possible substitution of the dangerous substance by one that is non-hazardous; or one that is less hazardous.

Remember the recent incident involving an ignition of vapour produced from a cleaning fluid in an aviation fuel tank that was being fabricated. During the investigation it was found that the cleaning fluid that the vapour was produced from was ineffective as a cleaning agent and that a detergent and water mixture would have been more effective. Unfortunately, this incident resulted in an employee suffering a life changing injury, considerable pain, being confined to a wheel chair and never being able to work again.

“it is always good practice to involve employees in the risk assessment process, they will most likely be present and involved if something goes wrong”

If ever there was an advert for risk assessment, this is it.

Step 4
You must the record your risk assessment and ensure that the identified control measures are shared with and implemented by your employees (or contractors).

It is always good practice to involve employees in the risk assessment process. After all, they do the work and will most likely be present and involved if something goes wrong.

The risk assessment should also assist you in deciding on the information, instruction and training you give to your employees.

This training should ensure that your employees understand (knowledge) and are competent in operations (performance) and also in the requirements to protect themselves and others from the potentially explosive atmosphere. Training should also be provided in the arrangements to minimise the risks if accidents, incidents and emergencies do unfortunately occur. This training should also include liaising and communicating with the public emergency services. It should be remembered and noted that reliance solely on the public emergency services to deal with industrial emergencies will not normally mean you are complying with the legal or regulatory requirements. This is specifically mentioned in the confined space regulations.

Step 5
Review your risk assessment and update if necessary.

If you introduce significant changes in your processes or equipment you should review your risk assessment.

Similarly, you should review your risk assessment in the event of an incident, including a near miss.

For example, if a release of a dangerous substance that creates an explosive atmosphere occurs without an ignition, review your risk assessment to determine if the control measures you have identified are effective.

Do not forget to include non-routine activities in your risk assessment, such as maintenance work, outages, etc. where there is often a higher potential for fire and explosion incidents to occur.

Remember you should always look for alternatives to eliminate or reduce the risk by, for example, replacing the flammable substance with another non-flammable substance or changing or altering a work process.

In reality, this may be difficult to achieve, especially where the flammable substance is used as a fuel.

Reminder on control measures

Your focus should be on prioritising control measures as follows:

  • Reduce the quantity of dangerous substances to a minimum
  • Avoid or minimise releases of dangerous substances
  • Control releases of dangerous substances at source
  • Prevent the formation of an explosive atmosphere
  • Include ventilation
  • Collect, contain and remove any releases to a safe place
  • Avoid ignition sources
  • Avoid adverse conditions such as exceeding pressure/temperature limits that could lead to an explosive atmosphere being created
  • Keep incompatible substances apart - someone in a place I once worked at mixed two cleaning fluids together and immediately collapsed – lesson learned

Mitigation

After the implementation of the control measures to minimise the risk of an explosion or fire the next priority is to identify and implement mitigation measures to reduce the detrimental effects of a fire, explosion or similar incident should one occur. (these can be included along with the control measure contained within the risk assessment documentation)

“identify and implement mitigation measures to reduce the detrimental effects of a fire, explosion or similar incident should one occur”

They can include the following:

  • Reduce the number of employees exposed to the risk
  • Provide plant and equipment that is explosion resistant
  • Provide explosion suppression or explosion relief equipment
  • Take measures to control or minimise the spread of fires or explosions
  • Provide suitable personal protective equipment (PPE) but only as a last resort

Explosion risk zones

As part of your risk assessment it is good practice and useful to identify explosion risk zones. This identification should be based on the likelihood and persistence of a fire or explosion occurring.

This is known as Hazardous Area Classification (HAC). HAC is useful in identifying the equipment that can be used in the area and the competence of employees required to enter and operate in the hazardous area.

An example of HAC is:

Zone 0
hat part of a hazardous area in which an explosive atmosphere is continuously present, or present for long periods, or frequently.

Zone 1
That part of a hazardous area in which an explosive atmosphere is likely to occur occasionally in normal operation.

Zone 2
That part of a hazardous area in which an explosive atmosphere is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

For the hazardous areas identified, you should ensure that all potential ignition sources, including sparks, hot surfaces, smoking materials, naked flames, unsuitable equipment etc are excluded; only equipment and protective systems, including portable equipment that meets the requirements of the Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 1996, should be used and installed. Such equipment will be CE marked and carry the εx symbol in a hexagon.

Prior to using equipment in a hazardous area and as part of the commissioning procedure, an employee or contractor competent to do so should verify that the equipment and protective systems provided are suitable and sufficient to make sure the fire and explosion risks are properly controlled.

Suppliers and/or contractors who provide, maintain or verify electrical installations and equipment for use in or near hazardous areas must be competent (knowledge and performance) in this role. It is good practice to ensure that a warning notice or sign is positioned at the entry points of places that have been classified as hazardous areas to warn those entering these areas that special precautions are required.

Information, instruction and training

It is very beneficial and important to include and involve employees who are working in explosive atmospheres when undertaking risk assessment. This also applies when developing and producing information packs and training programmes.

The information, instruction and training for employees should include details of the dangerous substances in the workplace and the risks they present. These should include:

  • Safety data sheets
  • Information on any legislation that applies to the dangerous substance
  • The findings of the risk assessment
  • The control and mitigation measures put in place
  • Emergency procedures

Do not forget to provide information and site inductions to visitors to the site or process area to ensure their safety and to ensure they do not cause an incident or accident due to a lack of knowledge or understanding of the hazards and risks involved.

It is and can also be good practice to provide and share information to others within the community around or near the site. This is for reassurance purposes. It is also good practice that if an incident occurs at a site to explain to the local community, when possible, what happened and why the incident occurred.

All pipes, containers and other devices utilised to transport flammable substances around or between sites and process areas should be clearly identifiable so that employees and others are fully aware of what is being transported.

Emergency arrangements

You must also assess the likelihood and the effect of a foreseeable accident, incident, emergency or other event involving a flammable atmosphere in your work area. You should then ensure that suitable and effective emergency arrangements are in place to protect, save and preserve endangered lives of your employees and others. These emergency arrangements should also be capable of reducing the impact of the accident, incident or emergency.

Emergency arrangements should be tested regularly to ensure they are effective. These “mock emergencies” should include the site warning and communication systems, the emergency response and the first-aid facilities. Mock emergencies should test the competence of all involved. Mock emergencies should be a realistic simulation of a potential event. Those involved should find the “mock” to be challenging.

The debrief of a mock should always identify improvements to the systems, processes and training requirements.

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Andrew Watson has worked in the mining industry for over 40 years and has been an operational mines rescue officer for 35 of these years. He is the Commercial and Business Development Director for MRS Training and Rescue, (the Mines Rescue Service) which offer...
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