28 Mar 2019
Oxidising agents or oxidising substances are materials that react with oxygen, which causes one substance to be reduced through loss of electrons. On the macro level, these can increase heat, gas, and even produce flames. This can occur through simple exposure to air. Fires which occur due to unsafe storage can harm workers and the environment, ranging from third-degree burns, which can be fatal. Fires can devastate workplaces, inventory, and personal effects. Exposure to oxidising agents such as potassium nitrate or nitric acid can also have harmful effects when inhaled or by contact with skin. The Australian Dangerous Goods Code classifies oxidising substances as Division 5.1 and has strict guidelines when it comes to storage.
Preventing the Triangle of Combustion
The aim of any oxidising agent storage system is preventing the triangle of combustion. Fire needs an oxidising agent (usually air), fuel (wood, paper, etc.) and heat to maintain and spread. Removing one of these elements reduces or eliminates the risk of fire. Oxidising agents not only increase the rate at which a fire develops, it can also aid other substances to combust more rapidly in air. Therefore a ventilation system is required to stop the triangle of combustion from forming.
Compliant Ventilation Systems for Oxidising Agents
The Australian standard outlining ventilation requirements for oxidising agent storage cabinets is AS 4326-2008. The standard outlines that cabinets shall be vented to atmosphere, away from ignition sources and areas where persons are likely to congregate. This is a mandatory requirement. An oxidising cabinet without ventilation is not compliant under the standard. Non-compliant systems may cause health risks to your employees, which include nausea, vomiting, irritation to the eyes and throat, and in extreme cases, asphyxiation. It’s important you log and categorise any oxidising agent that comes into your workplace and store it properly according to the standard.
Features of a Cabinet for Storing Oxidising Agents
An oxidising agent cabinet must have a liquid tight spill sump, made of double-walled sheet steel with at least 40mm of space between the walls. This may be filled with non-flammable material or left vacant. The cabinet shelves must be perforated to allow for free air movement. Venting should be directed away from potential ignition sources and through the top of the cabinet. The doors of the cabinet must be self-closing and close-fitting, without any air gaps. They cannot be made with plastic or zinc. Indoor storage cabinets may hold no more than 250L/kg of oxidising chemicals, with an outdoor cabinet limited to 850L/kg.
Pictured: Oxidising Agent Storage Cabinets
A Note on Ventilation Systems
Note that ventilation systems cannot be “daisy chained” together, as mixtures of oxidising agents can cause violent chemical reactions. Ventilation systems must be designed by a qualified engineer to prevent weakening the structure of the cabinet and comply with AS/NZS - 1668.2-2002.
To find out more and to see our range of compliant cabinets and ventilation systems, contact BackSafe Australia today.
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