MRS TRAINING & RESCUE
The new name for...
Mines Rescue Service
CONFINED
SPACE GAS
DETECTION
What is an enclosed space?
The Oxford compact English dictionary defines
enclosed as “shut in on all sides” / “secluded from
the outside world”. Enclosed nature suggests that an
individual entering / exiting / working in such an area
will have some constraints / restrictions.
What makes an enclosed space a confined space?
It is not necessarily a cramped place. It is any place,
such as a chamber, tank, vat, silo, pit, trench, pipe,
sewer, flue, well or other similar space in which, by the
nature of its enclosure, there are risks identified within
the enclosed space.
DETECTING GAS - RISKS IDENTIFIED & CONTROLLED
Employers have a duty to protect their employees and
ensure their safety and health, so they must be aware
of and understand the hazards associated with confined
spaces.
The main risk to an employee in a confined space is the
loss of consciousness or asphyxiation arising from gas,
fume, vapour or the lack of oxygen.
HAZARD IDENTIFICATION & ASSESSMENT
Risk: Gas (or lack of a gas) within a confined space
Conditions within and around the confined space should
be assessed to identify what gases could be present, or
could be introduced into the confined space, by whatever
work is to be carried. This isn’t necessarily just in the
confined space - it could be in an area associated with the
confined space.
Never forget to assess which gases are potentially not
present (i.e. oxygen).
The most acceptable environment within a confined
space will be “fresh air”. Fresh air is defined as a complex
mixture of gases. The three main constituent gases in air
are oxygen, nitrogen and carbon dioxide. Their composition
is generally accepted as being: Oxygen - 20.93%, Nitrogen -
79.04%, and Carbon D ioxide - 0.03%.
As air is a combination of gases, it is possible for
individual gases to be isolated through particular
processes. It is always advisable to consider previous
records of entries into the confined space for factual
information on the environmental conditions encountered
on those entries.
WHAT ARE THE RISKS WITHIN A CONFINED SPACE?
They are:
▪ serious injury to any person at work arising from a
fire or explosion;
▪ the loss of consciousness of any person at work
arising from an increase in body temperature;
▪ the loss of consciousness or asphyxiation of any
person at work arising from gas, fume, vapour or the
lack of oxygen;
▪ the drowning of any person at work arising from an
increase in the level of liquid;
▪ the asphyxiation of any person at work arising
from a free flowing solid or the inability to reach a
respirable environment due to entrapment by a free
flowing solid.
HSE INTERNATIONAL
37