Canadian Occupational Safety

July/August 2020

Canadian Occupational Safety (COS) magazine is the premier workplace health and safety publication in Canada. We cover a wide range of topics ranging from office to heavy industry, and from general safety management to specific workplace hazards.

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Page 19 of 31

F E A T U R E 20 talks about general use, storage and such. I would check the fire code and then the OHS legislation for the specific requirements. It might go above and beyond the fire code," he says. When handling a flammable liquid, workers should aim to limit the vapour concentration in the air to prevent ignition. Before starting work, it's present, says Simon Fridlyand, president of Toronto-based S.A.F.E. Engineering. There must be a fuel (vapour); oxygen (air) and an ignition source. If the mixture of flammable vapour and air catches fire, the flames travel quickly through it. A fire may occur when an ignition source is too close to the liquid's surface, where there tends to be a high concentration of vapours. It can also occur when a worker is dealing with a high quantity of flammable liquid and the vapours are allowed to build up in the workplace atmosphere. If the concentration of vapours in air becomes hazardous, any ignition source can cause a fire. When, in addition to the flammable mixture and ignition source, there's also an enclosure — a storage tank or a room where flammable liquids are processed, for example — there could be an explosion. Explosions can be powerful, resulting in the collapse of an entire building. Proper handling of flammable liquids The handling and storing of flammable liquids requires knowledge of a variety of regulations, codes and standards, says Greg Hodgson, occupational hygienist in the department of Environment, Health and Safety at the University of Alberta in Edmonton. Employers must consult the fire code of the local jurisdiction and other applicable safety codes, as well as provincial occupational health and safety law. "The OHS is usually specific to certain processes, where the fire code important for them to be aware of the lower flammable and explosive limit and the upper flammable and explosive limit of the chemical they are handling. This will tell them the range of concentration within which the chemical is hazardous. "Even when you're working with small amounts of liquid, it's evaporating, "Any area where you're working with flammable liquids should have either local exhaust or general dilution ventilation to prevent the buildup of vapours." Greg Hodgson, occupational hygienist, University of Alberta in Edmonton Source: U.S. Occupational Health and Safety Act 1910.106(a)(19)(i–v) 4 CATEGORIES OF FLAMMABLE LIQUIDS Category 1 : liquids having flashpoints below 73.4°F (23°C) and having a boiling point at or below 95°F (35°C). Category 2 : liquids having flashpoints below 73.4°F (23°C) and having a boiling point above 95°F (35°C). Category 3 : liquids having flashpoints at or above 73.4°F (23°C) and at or below 140°F (60°C). Category 4 : liquids having flashpoints above 140°F (60°C) and at or below 199.4°F (93°C). and the key is to control the vapour that's coming off the liquid to prevent it from reaching the lower explosive and lower flammable limit," Hodgson says. At the same time, workers must eliminate or control ignition sources — open flames, hot surfaces, spark- producing mechanical equipment, electrical equipment, static electricity and welding and cutting operations — near the work area or in areas where vapours may accumulate. Flammable liquid vapours are heavier than air and tend to fall and gather in lower areas. If vapours are ignited in these spaces, the flame may travel back or "flash" back, to the flammable liquid. The risk from some ignition sources, such as static electricity, can be very difficult to mitigate, Fridlyand says. "Very low ignition energy is required to ignite flammable vapours; static electricity can be generated by your

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