Confined Spaces 

Section 4   Safety and Operational Procedures 

occasion the confined space is re entered even when the atmosphere was 

initially found to be safe. 

4.8.6  

A sufficient number of monitoring devices must be in place at the work 

location to provide adequate cover of the work being undertaken or in the 

event of a monitor failing. 

4.8.7  

Atmospheric testing is to be carried out by members of the Work Team 

who are trained and competent to use the monitoring device/s, aware of 

the existing standards for the relevant airborne contaminates being 

measured, instructed and trained in the risks involved and capable of 

interpreting the results and taking any necessary action. 

Ventilation/Gas Purging 

4.8.8  

Every effort should be made to maximise the natural ventilation of the 

confined space prior to entry into and during occupation of the space. 

4.8.9  

Where the risk assessment has identified the presence or possible presence 

of flammable or toxic gases or vapours there may be the need for purging 

of the gases/vapours from the confined space.  If the gas present is above 

the flammable limit purging with inert gas is essential.  Where the 

presence of flammable or toxic gases or vapours is suspected, guidance 

from a person with relevant specialist experience must be obtained. 

4.8.10 

When carrying out purging/venting of a confined space precautions should 

be taken to protect those outside the confined space from exposure to 

toxic, flammable, irritating gases and vapours etc. 

4.8.11 

On sewers, at least one manhole upstream and downstream of the access 

manhole should be opened where practicable. 

4.8.12 

Other situations require the opening of the maximum number of openings 

available to provide sufficient natural ventilation. 

4.8.13 

Where necessary to achieve adequate ventilation, mechanical means of 

ventilation may be used, e.g. using a blower fan and trunking.  The fresh 

air will need to be drawn from a point where it is not contaminated by used 

air or other pollutants. 

4.8.14 

Oxygen must never be used to ventilate the space or as a means to 

"sweeten" the air. 

Removal of Residues

4.8.15 

Appropriate measures must be taken where the risks from residues are 

identified. 

4.8.16 

Measures to be taken may include the use of powered ventilation, specially 

protected electrical equipment for use in hazardous atmospheres, 

respiratory protective equipment and atmospheric monitoring. 

4.8.17 

Where the presence of petroleum products are suspected, the Authorised 

Person (Petroleum) should be consulted. 

April 2005 

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