Flammable Substances – Ten facts you might never have known

Did you know that a cloth or brush used to apply certain kinds of furniture preservative can catch fire of its own accord? Or that vapours from flammable liquids can flow like water? If not, you need Safety Storage Centre’s list of ten facts about flammable substances, and maybe a flammable storage cabinet too…

Modern workplaces and homes require the use of a broad spectrum of flammable substances, each of which presents similar, but slightly different hazards.

They’re all so familiar to us that there is a danger of being too relaxed around them, which is why the Safety Storage Centre has produced this list of ten facts you might not have been aware of when thinking about flammable substances.

1. Flammable liquids don’t burn. Burning happens when the conditions are right for the liquid to give off vapour into the atmosphere. It’s the vapour, mixed with the oxygen in the air, which burns, rather than the body of the liquid itself.

2. ‘Flammable’ doesn’t mean ‘combustible’. The words are not interchangeable, even though the distinction might be seen as a technicality. It’s about temperature, or more precisely, flashpoint. Flashpoint is the minimum temperature at which a liquid can form sufficient vapour to be ignited above its surface. As a general rule, liquids which have a flashpoint below 37.8oC (or 100oF) are said to be flammable; those that have a flashpoint above that temperature are combustible.

3. Vapours can flow like water. Some hazardous vapours are denser, and therefore heavier than air; others are lighter. The heavier ones can flow like water and pool in unventilated areas such as boat bilges, where they can lay undetected until an ignition source creates a spark leading to an explosion. In the event of a fire, it can spread along a vapour trail and cause a fire some distance away from the ignition source. When working around hazardous vapours, never ventilate an area with an electric fan; turning it on could provide the source of ignition. This is called flashback.

4. Flashpoints are like fingerprints. Every substance has a different one, and they can vary widely. Before working with any flammable or combustible substance, you need to know what its flashpoint is, and act accordingly.

5. The difference between ‘lean’ and ‘rich’. Most often used when talking about petrol engines, these terms refer to ‘flammable’ or ‘explosive’ limits. These are the concentrations above and below which vapours can’t be ignited. In the case of petrol, the lowest limit is 1.4%, (below which the engine won’t run well because the mixture is too lean). The upper limit is 7.6%, above which it is too rich. However, these figures are intended as guides. Always err on the side of caution.

6. A source of ignition isn’t always necessary. Substances have the capability to ‘go it alone’ in the explosion and fire stakes. That happens when they reach their auto-ignition temperature, at which point they will catch fire.

Flammable Substance

7. Static electricity on clothing can ignite a vapour. The tiniest spark can cause a fire, and that includes static electricity earthed from clothing. Wearing cotton reduces static build-up, and avoiding rubber-soled shoes, which are great insulators, will help static to disperse as it forms.

8. Oily rags can spontaneously combust. Alarmingly, when there’s been a spill clean up, the danger isn’t over until the cleaning cloths are safely disposed of, because they can catch fire of their own accord due to heat released as a result of a process known as oxidation. This is even true for some apparently harmless oil-based furniture treatments, where the application cloths or brushes need to be treated with the upmost respect, and disposed of or washed carefully.

9. Nylon will stick to the skin when it burns. That’s because it’s a man-made fibre, and will melt. Far better to wear natural fibres. Wool’s good, but remember the thought about static electricity in item 7.

10. Fire isn’t the only danger. Flammable substances can cause harm to health through exposure to the skin. They can be corrosive, and although their vapours are usually invisible, they can cause headaches, nausea, dizziness, and irritation of the eyes or throat. And that’s just another reason to make sure that they’re stored and handled correctly.

Storage of flammables – how to do it safely

Here are a few basic rules about storage of flammables, and they’re covered mainly by the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR). The Health and Safety Executive goes into much more detail on its website.

The Regulations say that in terms of liquids, it’s best to keep the smallest-possible quantity in the workplace at any one time – enough for half a day, or a single shift. When not in use, containers need to be kept in a suitable cabinet or bin not only designed to resist fire, but also to contain spills – up to 110% of the largest vessel normally stored in it.

This is where flammable storage cabinets can be so important for the safe storage of these dangerous flammable substances. You must also think of placement of any flammable storage cabinet. Although they need to be close to the workplace for the sake of convenience, they need to be in places outside the work area, and where they won’t get in the way of an evacuation.

All kinds of sizes of flammable storage cabinet are available and we have a full range at the Safety Storage Centre. It may even be that more than one cabinet is required; regulations about the storage of flammables require that different classes of hazardous substance should not be mixed.

We understand that flammable substance storage can be tricky and we’d love to help. Visit our website and give us a call.

Picture: Fotoknips via Dreamstime.

Hazardous Substance Storage

The storage of chemical substances – those that are potentially hazardous – is vitally important; however, whilst a flammable cabinet will provide a significant amount of protection against the effects of these dangerous substances, it is important to remember that some chemicals will need to be stored away separately.

For example, oxidising acids should never be stored with flammable solvents. Storing two incompatible substances in the same cabinet can result in disaster – causing the two to mix to form heat, harmful vapours, as well as explosions between the most volatile of chemicals.

When these chemicals are stored away it is also important to ensure that the container lids and caps are tightly secured – in order to prevent the substances from leaking out into the cabinet. Many will assume that because a storage cabinet is fireproof, it will also work as a corrosive cabinet – this, however, is simply not the case. Separate cabinets will have different attributes and it is therefore important to have the correct cabinet to contain the chemicals you intend to store in it.

See our Advice Pages for more help on the Chemical Compatibility.