When you are using a number of different dangerous substances in the workplace, its very important that you store and handle them in a way that minimises the risk of incompatible classes of dangerous goods mixing and causing violent chemical reactions. Two commonly used classes of dangerous goods that have the potential to react dangerously are Class 3 Flammable Liquids and Division 5.1 Oxidising Agents. So that you can understand how a mixture of these two dangerous goods classes can cause harm to the people in your organisation, we will first look at the definition given by the ADG Code for flammable liquids and oxidising agents.
Class 3 Flammable Liquids
According to the Australian Dangerous Goods Code, flammable liquids are defined 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. This class also includes:
- liquids offered for transport at temperatures at or above their flash point; and
- substances that are transported or offered for transport at elevated temperatures in a liquid state and which give off a flammable vapour at a temperature at or below the maximum transport temperature.
Division 5.1 Oxidising Agents
According to the Australian Dangerous Goods Code, Oxidising Agents are defined as:
Substances which, while in themselves not necessarily combustible, may, generally by yielding oxygen, cause, or contribute to, the combustion of other material. Such substances may be contained in an article;
How flammable liquids and oxidising agents react dangerously
For combustion to successfully take place there are three critical elements required. These elements include:
- Fuel (flammable liquid)
- Oxygen (oxidising agent)
Therefore, if flammable liquids and oxidising agents are mixed, it will produce an extremely flammable mixture of substances. If an ignition source such as a spark came into contact with this flammable mixture, it would ignite instantaneously. Oxidising agents have the ability to provide excessive amounts of oxygen to enrich flammable and combustible substances causing them to ignite at much lower temperatures than they would normally. To avoid these dangerous reactions that cause a lot of harm to people, property and the environment, it’s essential to segregate flammable liquids and oxidising agents during storage.
Segregation according to the Australian Standards
To avoid harm to the people and property of your organisation, incompatible classes of dangerous goods can be segregated by following the guidelines set out in the Australian Standards.The Australian Standards provide industry with precise guidelines on how to store dangerous goods in way that minimises risk to people, property and the environment.
The Australian Standard that outlines the requirements for storing incompatible classes of dangerous goods is, AS3833-2008 - The storage and handling of mixed classes of dangerous goods. This standard contains a Dangerous Goods Segregation Chart that outlines the separation distances for storing incompatible classes of dangerous goods. This segregation chart interprets that:
“When Class 3 Flammable Liquids and Division 5.1 Oxidising Agents are stored in a common dangerous goods store, they must be segregated by at least 5 meters and kept in separate compounds that don’t share a common drainage system.”
If you have a common dangerous goods store that contains mixed classes of dangerous goods, you should carry out a dangerous goods risk assessment and identify all the substances that are flammable liquids and all those that are classified as oxidising agents. These substances must then be segregated by at least 5 meters and stored in different compounds that have separate drainage systems. If you do not have the space available in your dangerous goods store to segregate flammable liquids and oxidising agents by these distances, you can safely segregate incompatible classes of dangerous goods by using separate chemical storage cabinets.
Applying segregation with chemical storage cabinets
Chemical storage cabinets allow incompatible classes of dangerous goods such as flammable liquids and oxidising agents to be segregated without separating them by impractical distances such as 5 meters.
There are nine different classes of dangerous goods and each chemical storage cabinet is manufactured to store a specific dangerous good class. This is because different classes of dangerous goods have different hazardous properties and dangerous goods storage cabinets are designed to shield people and property from the specific hazards presented by the dangerous goods class. We will now outline the requirements for flammable storage cabinets and oxidising agent storage cabinets.
Flammable storage cabinet requirements
If you choose to segregate oxidising agents from flammable liquids by using chemical storage cabinets, the cabinet used for the storage of flammable liquids must comply with the requirements outlined in AS1940-2017- The storage and handling of flammable and combustible liquids. The walls, floor, roof and doors of flammable storage cabinets must have a double walled sheet steel construction. This double walled sheet steel construction provides the cabinet with insulation from ignition sources that could potentially ignite the flammable liquids within the cabinet. Other construction requirements for flammable storage cabinets include:
- Any gaps between the doors and the walls must be sealed to prevent the spread of flames and heat radiation.
- Any materials that are critical to the structural integrity of the cabinets construction must not melt at temperatures below 850 degrees celsius.
- If the doors of the cabinet must be fitted with a device that keeps them open while in use, the device must automatically release at temperatures exceeding 80 degrees celsius.
- The doors of the cabinet must be self-closing, closing fitting and held shut by at least two catches
- The cabinet shall be designed so that any spills that may occur inside the cabinet are directed into the spill containment sump at the bottom of the cabinet.
- Any shelving inside the cabinet must be perforated to allow for free air-movement
- The base of the cabinet must form a liquid-tight sump with a depth of at least 150mm. The sump should be designed in such a way that packages of flammable liquids are prevented from being stored inside it.
To ensure that everyone in the workplace is aware of the potential risks associated with flammable liquids, all flammable storage cabinets must be marked with clear safety signs. The dangerous goods signage requirements for flammable storage cabinets is outlined below:
Class 3 - Flammable Liquids
No Smoking No Ignition Sources Within 3 Meters
Oxidising agent cabinet storage requirements
When segregating oxidising agents from flammable liquids using chemical storage cabinets, its important to use an oxidising agent storage cabinet that complies with the Australian Dangerous Goods Standards. The Australian Standard that outlines the requirements for oxidising agent storage cabinets is AS 4326-2008 - The storage and handling of oxidising agents. This standard states that oxidising agent storage cabinets must have doors that are held shut by catches that automatically release in the event of a build up of pressure. Other construction requirements include:
- The walls, floor, doors and roof of the cabinet must be constructed from a double walled sheet steel construction. The gap between the walls must be at least 40mm. This gap can be an open air space or filled with non-flammable non-combustible insulation.
- The cabinet must have doors that are self-closing and close-fitting.
- The door catches and hinges must not be constructed from plastics or zinc die castings
- The cabinet must have a lower liquid-tight compound that is at least 150 mm deep and capable of containing at least 25% of the aggregate capacity of the storage cabinet.
- Any shelves within the cabinet must be perforated to allow for free air-movement.
- Where appropriate, oxidising agent storage cabinets must be vented to the outside atmosphere and away from any ignition sources and places where people congregate.
To ensure that everyone in the workplace is aware of the potential hazards associated with oxidising agents, it’s important to display clear safety signage on the front of all safety cabinets used for the storage of oxidising agents. The dangerous goods placarding requirements for oxidising agent storage cabinets is outlined below:
Division 5.1 Oxidising Agents
As flammable liquids and oxidising agents form two of the key elements for a combustion reaction to take place, it’s very important that you store and segregate flammable liquids and oxidising agents in a way that minimises risk to people, property and the environment. If you would like a free dangerous goods segregation chart to help identify the segregation distances for incompatible classes of dangerous goods, download our free segregation chart by clicking on the image below 👇.