If your organisation uses flammable liquids on a regular basis, it is very important that you store and handle these dangerous goods in a way that minimises their risk upon the people, property and environment of your organisation. One major dangerous property of flammable liquids is their flammability due to their low flash point. The Australian Dangerous Goods code defines flammable liquids as:
‘Flammable liquids are liquids, or mixtures of liquids, or liquids containing solids in solution or suspension (for example, paints, varnishes, lacquers, etc., but not including substances otherwise classified on account of their dangerous characteristics) which give off a flammable vapour at temperatures of not more than 60 °C, closed-cup test, or not more than 65.6 °C, open-cup test, normally referred to as the flash point.’
As described in the definition above, flammable liquids are liquids that give off a flammable vapour at temperature below 60°C. These flammable vapours are very volatile and they must be controlled in such a way that they pose minimum risk to your organisation. The risk posed by these flammable vapours can be controlled by installing a ventilation system on your flammable liquids storage cabinets.
Ventilation requirements according to AS1940-2017
The standard that sets out the ventilation requirements for flammable storage cabinets is AS1940-2017 - The storage and handling of flammable and combustible liquids. Section 4.9.5 of this standards states:
Where ventilation is installed, it shall be designed so that vapours are prevented from escaping into any room. Any ventilation exhaust shall be to the outside atmosphere and in a location which allows the safe dispersal of vapours and is away from any ignition sources (see Clause 4.5).
As this standard doesn’t state that a ventilation system “shall” be installed, it means that ventilation of flammable liquid storage cabinets is not a mandatory requirement, however it should be done if it’s part of a risk control measure. An instance where ventilation would be required is if the flammable vapours inside the cabinet exceed the workplace exposure standards.
Workplace exposure standards
Exposure to hazardous substances can have significant health risks to workers. Some of these risks include:
- Irritation to the eyes, ears and throat
To combat these health risks, Safework Australia developed the workplace exposure standards. These standards identify approximately 700 hazardous substances and their legal airborne concentration limits.
If the flammable liquids stored inside a cabinet are listed in the workplace exposure standards and the concentration of the vapours exceed the legal limit, the cabinet will need to be ventilated. The ventilation system will reduce the concentration of the flammable vapours, making the area safe for people to work in.
Features of a compliant ventilation system
If you carry out a dangerous goods risk assessment and determine that your flammable storage cabinets require a ventilation system, it is very important that your ventilation system is installed in such a way that it doesn’t pose any further risks to the people of your organisation. A safe ventilation system must follow the requirements outlined below:
- A mechanical ventilation system should be designed so that it prevents any vapours from escaping into the room.
- The ventilation system shall be vented to the outside atmosphere in a location that is safe to disperse vapours. A safe location will be away from ignition sources and places where people congregate.
- The air inlet shall be attached to the vent port at the top of the cabinet and the vapours shall be extracted from the bottom vent port using an exhaust fan. This configuration is most effective as most dangerous vapours are heavier than air and reside in the bottom of the cabinet.
- Any ventilation system that is used to extract flammable vapours will need to have an intrinsically safe exhaust fan.
- A ventilation system cannot be linked to multiple cabinets as this can cause vapours from incompatible dangerous goods to mix, resulting in violent reactions.
- When a mechanical ventilation system is not attached to a cabinet, the vent bungs must be tightly screwed into the vent ports. This stops any dangerous vapours from escaping into the workplace.
- In all instances the ventilation system shall not compromise the structural integrity of the cabinet.
- In all cases the ventilation duct shall not be smaller than the size of the venting opening on the side of the cabinet. A ventilation system shall be designed by an appropriately qualified engineer and it shall comply with AS/NZS - 1668.2-2002
As flammable vapours can pose severe health hazards upon the people of your organisation it is good practice to vent flammable storage cabinets to bring the concentration of flammable vapours down to a safe limit. For a ventilation system to be safe, it must follow the best practices outlined above and comply with the requirements specified in AS1940-2017. For more detailed information on how to ventilate dangerous goods storage cabinets, download our free eBook by clicking on the image below 👇.