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*                        INFORMATION ALERT                          *  
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*  Produced by:  Saskatchewan Human Resources,                      *  
*                Labour and Employment                              *  
*  Provided by:  Canadian Centre for Occupational Health and Safety *  
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VENTILATION PROCEDURES FOR CONFINED SPACES  
  
  
  Forced ventilaiton of a confined space provides fresh air to remove  
  toxic fumes and/or provide a safe level of oxygen.  Ventilation should  
  include the following procedures:  
  
                1.  All openings to the confined space should be open to allow  
                    maximum dilution of contaminants.  
  
                2.  Fresh air should be introduced with a positive pressure  
                    air blower (see diagram) where the highest concentration  
                    of contaminants in the confined space exist.  Prevent  
                    toxic materials such as motor exhaust from being supplied  
                    to the confined space.  Locate the blower intake in an  
                    area where only fresh air exists.  
  
                3.  No one type of ventilation system will work effectively  
                    in all types of confined spaces.  The selection of the  
                    ventilation system to be used will depend on the type of  
                    work performed, vessel configuration and toxic gas  
                    concentration.  The ventilation rate needed is very  
                    important.  In most cases, testing of the atmosphere  
                    in the confined space will be required before workers may  
                    enter, even when ventilation is used.  See the branch  
                    brochure 'Safe Entry Into Confined Spaces' for more  
                    information.  
  
                4.  Care should be taken to avoid creating pockets of toxic  
                    or flammable gas by the discharge of vapours from  
                    the confined space.  
  
                5.  Equipment must be grounded and bonded to the structure of  
                    the confined space.  Failure to do so may result in a  
                    discharge of static electricity and an explosion.  
                    Electrical equipment used in a confied space must meet  
                    requirements of Part I of 'The Canadian Electrical Code'  
                    and 'Saskatchewan Supplement'.  
  
                6.  Oxygen should not be used for ventilation.  In a confined  
                    space oxygen can increase the risk of igniting flammable  
                    gas and/or creating uncontrolled chemical reactions.  
  
note:  the original document contains diagram on "A use of a positive  
       pressure air blower".  
  
  
Bulletin WSU 5, July 1990  
  
  
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