What’s the difference between an indoor and outdoor flammable liquids cabinet? 

Dec 2, 2019 Posted by Walter Ingles

One of the most common questions our team of Field Auditors get asked is … ‘should I store my flammable liquids indoors or outside?’ And like most Work Health and Safety questions, the answer is … ‘that depends’. In this blog we’ll be explaining the difference between an indoor and outdoor flammable liquids cabinet to help you decide which would be the safest and most efficient way to store the Class 3 Dangerous Goods at your workplace. 

Considerations when storing flammables 

Before you can decide on an indoor or outdoor cabinet, you need to consider the unique situation of your own job site. We consider the following 7 items essential. 

1. Ignition sources

Preventing flammable liquids from igniting is a primary consideration when choosing the best storage method. You need a cabinet or chemical store that can be installed away from hot work, machine generated heat, flames or electrical equipment that could spark if it discharged. Chemicals left outside can also be ignited by lightning strikes. 

2. Ventilation

Flammable liquids emit hazardous vapours that can ignite, as well as create exposure hazards if inhaled by workers or other people present in the area. Australian Standards require that flammable vapours must be safely dispersed and not allowed to accumulate in confined spaces including cabinets. 

Chemical concentrations in the air (most especially the breathing zones of workers) must be kept below workplace exposure standards. If this cannot be achieved using natural ventilation, a mechanical ventilation system will be required. Mechanical ventilation systems usually require ducting, exhaust fans, alarms and sensors. 

IMPORTANT: Keeping chemical concentrations within accepted workplace exposure standards also ensures vapours and fumes don’t reach their explosive range or create an asphyxiation hazard. 

3. Impact protection

Containers holding flammable liquids need to be protected from impact by vehicles (forklifts, company utes), flying debris (tree branches, malfunctioning machinery), and falling objects (tools dropped from construction zones, machinery falling from a mezzanine floor). Impacted containers can break then leak or even explode. 

4. Quantities

The quantities of chemicals you hold onsite will also determine whether your flammables are stored indoors or outside. Larger quantities of flammable liquids must be stored outdoors. 

5. Climate

Climate and overall site conditions must be included in your considerations. This includes activities occurring on adjacent properties eg, farming, domestic residences, forestry. Is the site vulnerable to temperature (extremes heat or cold), natural disasters (floods, cyclones), or frequent storms that produce a lot of electrical activity? 

6. Physical and health hazards

And of course you must consider the other physical properties of the chemicals that cause them to be toxic, corrosive, carcinogenic, reactive or otherwise unstable. Maybe you have other Hazardous Chemicals and Dangerous Goods stored onsite too, this will also impact where you store your flammables. 

7. Onsite wear and tear

Finally, consider the type of everyday use and handling a cabinet or chemical store might encounter. What type of working pressures and structural stresses are likely? Are the liquids being stored likely to attack and degrade the storage equipment?  

Indoor vs outdoor flammable liquids cabinets 

Feature 

Indoor cabinets 

Outdoors 

     

Thermal protection 

Indoor cabinets have dual-skinned walls and provide a level of thermal protection between the chemicals inside the cabinet and the exterior temperature. 

Outdoor cabinets don’t provide a thermal barrier but utilise natural ventilation to allow the air inside to move freely. 

Ventilation 

 

Indoor cabinets hold vapours and fumes and require an adjunct mechanical ventilation system if chemical concentrations cannot be maintained within workplace exposure standards. 

Outdoor cabinets provide natural ventilation because they have single skin louvered walls. 

Spill containment 

Indoor cabinets with a capacity between 30L and 250L have a liquid tight spill sump that is at least 150mm deep. Indoor cabinets that have a capacity between 250L and 850L have a spill sump that is 150mm deep and capable of holding at least 25% of the aggregate capacity of the cabinet.   

The capacity of the spill containment sump must be at least 100% of the volume of the largest package inside the store, plus 25% of the storage capacity up to 10 000L, together with 10% of the storage capacity between 10 000L and 100 000L, and 5% above 100 000L. 

Weather protection 

Indoor cabinets have flat roofs and are not designed for rain protection.  

Outdoor stores have cambered roofs that are engineered to maximise rainwater runoff. Outdoor stores are single-walled and vented so rainwater isn’t a problem. 

Stability 

Indoor cabinets cannot be fixed to the ground.  

Outdoor stores have engineered base plates and can be permanently fixed to the ground. That way they can’t blow over in a strong wind, or be knocked over by a vehicle. 

Impact protection 

Indoor cabinets are constructed from double-walled sheet steel and offer some impact protection. 

Outdoor cabinets are built from 25% stronger materials for greater impact protection. 

Cabinet size 

The maximum size for an indoor flammable liquids cabinet is 850 litres. 

There is no limit to the size of an outdoor store.  

Security 

Indoor cabinets have self-closing close fitting doors that latch at 2 points. These doors are also lockable. 

Outdoor cabinets have ISO locking bars that can be padlocked to secure the chemicals from theft. 

Portability 

Indoor cabinets are not designed to be moved around the site. 

STOREMASTA outdoor chemical stores are 100% portable and have forklift channels and lifting lugs for easy relocation.  

Grounding 

Indoor cabinets have no additional fittings for grounding. 

Outdoor cabinets have earth stake mountings to dissipate static discharge. 

Next steps

Now you know the difference between an indoor and outdoor flammable liquids cabinet, would you like more information about how to select and choose one? We invite you to download our free eBook Essential Considerations When Storing Flammable Liquids Indoors which provides essential information when choosing an indoor Class 3 Flammable Liquid Storage cabinet. Download and read it today by clicking on the image below:

Essential Considerations when Storing Flammable Liquids Indoors download Free eBook

Walter Ingles

Walter Ingles Compliance Specialist

Walter is STOREMASTA’s Dangerous Goods Storage Specialist. He helps organisations reduce risk and improve efficiencies in the storage and management of dangerous goods and hazardous chemicals.

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