Keeping Oxidisers and Flammable Liquids Apart 

Class 5.1 Oxidising Agents are materials and substances that can release oxygen. They present a compatibility issue and storage risk for flammable liquids as they can trigger a spontaneous fire in many combustibles (without the presence of a spark or flame) — as well as intensify any fire (making it burn hotter, longer) — and make it more difficult to extinguish. In this blog we’ll be looking at common hazards and storage considerations at worksites that carry both oxidisers and flammable liquids.

Storing flammables and oxidisers 

Flammable liquids and oxidising agents must be kept apart and should be separated according to the guidelines on the Safety Data Sheets. Best practice is to use a separation distance of at least 5 metres, but if you are using indoor safety cabinets (for both chemical types) you may be able to place the stores relatively close together. 

Cabinets for flammable liquids and oxidisers have different construction requirements, so the cabinets should never be interchanged or recommissioned. We’ll look at each separately below: 

 1. Flammable liquids cabinets

Flammable liquids cabinets have a double walled sheet steel construction and componentry that can withstand temperatures of more than 850°C. Doors must be self-closing and able to form a seal that protects the contents from flames and heat radiation. 

MORE INFO: AS1940:2017 –- The storage and handling of flammable and combustible liquids 

2. Cabinets for oxidising agents

Oxidising cabinets also have a double walled sheet steel construction, but unlike flammable liquids — cabinet materials for oxidising agents have no specific temperature requirement. Their doors are also self-closing but must have an in-built mechanism that will release if pressure builds up inside the cabinet. 

It is a strict requirement of Australian Standard AS4326:2008 that cabinets used for storing oxidisers must never be used to store other hazard classes of Dangerous Goods. 

For further information, refer to: AS4326:2008 — The storage and handling of oxidizing agents  

Identifying workplace compatibility hazards 

Keeping your oxidisers and flammable liquids separated while in storage is critical to onsite safety and chemical compliance, but you also need to consider other situations where these incompatible substances could contact one another. We recommend the following steps: 

Step 1 — Identify flammable liquids 

Step 2 — Identify oxidisers 

Now do the same for the oxidisers — eg, oxygen cylinders (welding, respirators/first aid, food production), fertilisers (eg, ammonium nitrate, nitric acid), hydrogen peroxide, cleaning agents, laboratory chemicals.  

Step 3 — Identify potential contact points 

Once you have a list of both flammable and oxidising chemicals, now look at all the ways they are used onsite and identify potential contact points. Your list should especially look at different work or maintenance activities that involve either flammable liquids or oxidisers. For example: 

• Oxy welding near fuel tanks or petrol operated machinery. 
• Cutting, grinding and welding at an agricultural worksite where fertilisers are kept. 
• Carrying out first aid and administering medical grade O2 near flammable liquids stores. 
• Pouring fuel into a compressor in proximity to the acetylene/O2 welding trolley. 

Taking corrective action

If you’ve identified any contact hazards between the two hazards classes you’ll need to take any necessary corrective action to eliminate (or minimise) the hazards. This may include: 

• Work design — implementing strategic design and layout of work areas. 

• Risk assessments — assessing risk before undertaking construction projects that require the use of mixed classes of Dangerous Goods including flammable liquids and oxidising agents. 
• Restrictions — placing greater restrictions on workers and external contractors who carry out welding, grinding and other maintenance work. 
• Site audits — working with Dangerous Goods auditors to help you review and implement safe work and storage systems. 
• Housekeeping — having consistent housekeeping practices. Eg, ensuring chemicals are put away promptly after use. 
• Safe work procedures — having clear and consistent operating procedures for all job tasks involving flammable liquids and oxidisers. 
• Training — ensuring workers and contractors fully understand the hazards associated with all the chemicals they work with (or may be exposed to). 
• Supervision — providing adequate supervision, ensuring managers and supervisors take immediate action if workers don’t follow safe work procedures. 

REMEMBER: You have a responsibility under Section 356 of Australian WHS Regulations to keep hazardous chemicals stable. This means ensuring that oxidising agents don’t significantly increase the risk associated with another chemical (eg, increasing the flammability and explosive potential of flammable liquids). 

Next steps 

Always carry out a risk assessment on your flammable liquids stores and ensure they are located away from oxidisers and other incompatible substances. For more information about keeping your indoor flammable liquids storage areas stable and compliant, please download our new eBook Essential Considerations When Storing Flammable Liquids Indoors. We walk you through the risk management process while outlining the primary considerations when selecting and installing a Class 3 Flammable Liquids cabinet. Download and read it today by clicking on the image below: