I’m not sure if I quite understand the question, but I think the answer is that venting is required any time it’s necessary to control combustible product ignition hazards. Here are some relevant provisions of the OHS Regs.
NB:
54An employer shall ensure that a bin, hopper or process vessel used to store bulk material
(a) is designed and built for removal of the material from the bottom,
(b) if the material is highly combustible, is provided with a lid and an adequate ventilation system and is fire-resistive,
65(2)An employer shall ensure that a carboy containing a liquid hazardous substance is
(a) individually encased in baskets or boxes cushioned with noncombustible packing,
260(1)An employer shall ensure that an enclosed or pneumatic conveyor used for carrying combustible or flammable material of an explosive nature is provided with an adequate explosion prevention system or with safety relief vents leading as directly as possible to the outside air and not connecting with any chimney pipe, vent or flue used for any other purpose.
PEI
43.25 Carboys (1) Carboys containing acids, which when in contact with living tissue will cause severe damage of such tissue by chemical action or in case of leakage will materially damage or destroy other material by chemical action or are liable to cause fire when in contact with organic matter, shall be encased singly in baskets or in boxes cushioned with non-combustible packing
43.36 Construction Bins used for storing highly combustible dry materials shall be of fire-resistant construction and provided with lids and an adequate ventilation system.
Hope that helps. If I missed the gist of your Q, feel free to give me another try. Or call me directly.
Glenn Demby 203 354-4532