Explosive Atmospheres and Workplace Safety

Organisations that typically use products that would be deemed to be dangerous substances must complete a risk assessment before conducting any activities involving products that might create an explosive atmosphere.

The depth of the risk assessment will always depend on the nature of the process undertaken, the hazards involved and who is likely to be affected and would most likely include the following factors:

• The types of dangerous substances and their inherent properties that could potentially lead to fire, explosion or other similar energetic reactions.
• The mechanism by which an explosive atmosphere might occur, including the possible failures of risk control measures that might lead to an explosive atmosphere forming.
• The likelihood that an explosive atmosphere might occur and its persistence.
• The likelihood that ignition sources might be present and might initiate fire, explosion or other energetic reactions.
• The scale of any foreseeable after-effects following combustion of an explosive atmosphere.
• Persons likely to be impacted, including employees, contractors, visitors or members of the public.

Where the presence of dangerous substances capable of producing an explosive atmosphere cannot be eliminated, the associated risks will need to be controlled or mitigated.

This can be done by introducing appropriate engineering and administrative controls to reduce the likelihood of a fire, explosion, or similar event happening or to minimise the consequences during and after such an occurrence.

1.     Zone Classification

All employers need to ensure that areas where dangerous explosive atmospheres may occur are classified into zones. The classification given to a particular zone, and its size and location will depend on the likelihood of an explosive atmosphere occurring and the persistence of that explosive atmosphere if it does.

Areas that are classified into zones must be protected from all sources of ignition, so it is critical that the relevant Fire Risk Assessment for the site or any process activities are consulted.

Work equipment and protective systems that are intended for use in any zoned areas must be appropriate for use in those zones. Where necessary, the entry points to areas classified into zones will need to be marked with appropriate warning signage.

2.     Safe Storage of Dangerous and Flammable Substances

It is imperative that all relevant storage facilities are maintained in a safe operational condition. All storage facilities need to have regular, scheduled inspections to be certain that they remain fit for purpose with all design control features correctly working.

Loading and unloading facilities need to be designed, located and operated to avoid or minimise the risks of fire and explosions throughout any transfer processes. Where gases and vapours are likely to be heavier than air, design considerations must factor in the potential for leaks into drains, voids and service ducts.

3.     Flammable Substances

Where flammable or oxidising gases are stored in transportable cylinders, organisations must ensure that safe methods of storage and handling are employed. Gas cylinders, except for fire extinguishers and those containing liquefied petroleum gas (LPG), must be colour-coded to clearly identify the contents and their properties.

Where liquids are stored above ground in any kind of bulk quantity, then the storage locations must be able to prevent spillages and contain those leaks.

Flammable substances need to be stored in a secure, ventilated area located in open air and away from occupied buildings, property boundaries and sources of ignition. Where those storage facilities are located inside any building, natural or mechanical ventilation needs to be provided.

Incompatible materials need to be segregated or adequately separated to minimise the risk of any adverse interactions. Flammable liquids must never be stored with oxidising agents, highly reactive metals or gas cylinders.

The contents of tanks, vessels and containers, must be clearly identified with appropriate signage so that employees are aware of their contents and hazards.

Flammable substances should never be disposed of into drains. Empty containers should be neutralised or cleaned and stored and disposed of in accordance with environmental requirements and safe disposable methods.

4.     Security Arrangements

Relevant security arrangements need to be provided to prevent unauthorised access to dangerous substances and associated storage equipment on site by means of suitable exterior fences, barriers of adequate height and strength, intruder alarms and security patrols.

Documented emergency procedures to mitigate reasonably foreseeable accident or incident scenarios for gas and flammable liquid leaks or fires, including equipment to deal with any accidental release or spillage, must be devised.

Employers must ensure that all emergency plans are regularly tested and revised accordingly as appropriate. The containment and subsequent disposal of all spillages must comply with relevant environmental legislative requirements.

If you have any questions about the safety measures in place to manage explosive atmospheres at work, now is the time to contact us. The Avensure Health and Safety team can provide the expert advice you need to keep your workplace safe, compliant, and ready for any potential hazards. Simply click here: Avensure Contact.