Fires in Dust Collectors and Hoppers
Alert I15: ISSN 1195-5228
Produced by the Industrial Health and Safety Program
Issued: December 1995
Hazard Summary:
Recently, firefighters were trying to remove smouldering sawdust from the hopper of a dust collector when an explosion blew burning materials out of the equipment. Six firefighters and eight workers suffered serious burns and cuts. The explosion happened 36 minutes after the fire apparatus arrived.
Explosions of this type may occur:
- when there is a movement of air into the interior of the dust collector or hopper, or
- when a sudden movement of materials causes dust to become suspended in air. Such movements may be caused either by efforts to clear materials so as to get at a source of combustion or by separate small explosions.
Affected Equipment/Locations and Sectors:
Dust collectors and hoppers that contain combustible dusts, such as sawdust and flour, are used in woodworking, furniture manufacturing, flour mills and mills processing dry food. Whenever ignition sources, like electric arcing, static electricity, friction and equipment malfunction, are present, there is a risk of explosion.
Recommended Precautions:
- The Ministry of Labour and the Office of the Fire Marshal strongly recommend that sprinkler protection and explosion venting be provided for dust collectors and hoppers because of the special problems of fighting fires in them. As a minimum, building owners should install a dry sprinkler head system piped to ground level for fire department use.
- Manufacturers' regular maintenance schedules should be followed to minimize potential ignition sources.
- Extreme caution should be exercised in opening access doors or unloading hoppers when a fire is involved. Everyone should first be moved to a safe distance. Where doors must be opened, the door handle may be hooked from a distance using a hook, pole and line.
Remember that while complying with occupational health and safety laws, you are also required to comply with applicable environmental laws.
Please photocopy Ministry of Labour Alerts, distribute them widely and post them where people will see them.
