Working safely in an explosive atmosphere
How do you define working in an explosive
atmosphere? It’s an environment where there is a mix of potentially dangerous
substances in the air, be they in the form of vapours, gases, dust or mist. If
ignited, combustion could spread to the whole unburned mix in the air, causing
an explosion.
A significant number of workplaces
undertake in activities that produce potentially explosive atmospheres. These
could be places where activities create gases or vapours that are flammable,
such as a vehicle paint spraying garage or a factory that handles organic dust,
like flour or wood.
Potentially explosive atmospheres occur
when these mists or vapours mix with air. The amount of substance required to
create this risk depends on the type of substance involved. These conditions
can be found in food processing plants, pharmaceutical factories, power plants
and chemical industries. Some industries might not be traditionally considered
as potentially explosive, such as a sawmill for example. However, if large
quantities of dust are left to accumulate, this then creates a risk of becoming
potentially explosive. Such environments must ensure that safety and air
quality monitoring are of the highest standards. For industries that require
local exhaust ventilation components, like a Spiral Duct, visit Dust Spares.
It is essential to recognise hazards by
carrying out a risk assessment. Factors that should be considered in a risk
assessment include:
The properties of the substances involved
The quantity of dangerous substance
involved
The types of work processes that will be
carried out, such as cleaning, maintenance or repair
The pressures and temperatures that the
substance will be kept at
The types of containment and control
systems in place to stop vapours, dusts, gases or liquids escaping into the
atmosphere
Measures in place to prevent explosive
atmospheres persisting for any length of time, such as ventilation
Ventilation
Whether the ventilation provided is natural
or produced by mechanical means, either method must be effective in diluting
the sources of release and removing them from any enclosed areas within the
workplace. A thorough and well-designed ventilation system is likely to be
required for zones of high concentration of hazardous substances or potential
sites of release.
When carrying out a risk assessment, it is
also essential to consider all of the possible sources of explosion risk that
might be present in the workplace. These include the storage of waste products,
cleaning materials and fuel, for example. It is also important to consider the
danger of chemical reaction when certain substances are combined. This could
result in a source of possible ignition being overlooked if this isn’t taken
into account during an assessment.
Other activities that could introduce a
source of ignition include refuelling vehicles, the loading and unloading of
tankers and any other activity where a spill could occur. In such areas, it is
important to isolate the power source, such as switching off engines.
Maintenance activities can also introduce a
source of ignition into a potentially hazardous environment. Ideally, the
dangerous substance should be removed before any maintenance work is carried
out. If specific control measures need to be put into place, this should all be
assessed before any work is completed.