Rank: Forum user 
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Hi all,
Can anyone adivse if there is any general guidance on the minimum distance that you should use an extremely flammable aerosol from an ignition source please?
I've seen mention of 750mm. I know that storage should be a minumum of 3m distance but this would be for use.
Any guidance would be appreciated!
Cheers!
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Rank: Super forum user
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Depends upon a number of factors. The propellant gas inside the aerosol - often its propane, but can be butane. The pressure inside a typical aersol is about 4 bar (60psi). The gas is likely to drop below LEL after about 0.3m. However,because users of aerosols tend to 'wave' the aerosol around, its in practice often difficult to determine the real world extent of the gas cloud. For ease of memory, on the site I'm at, we state aerosols should not be used with 1m of ignition sources. Electrical equipmen should be turned off or at least temporarily shielded/covered to stop over spray penetrating inside the equipment. The more obvious igniton sources like hot work/welding etc should be stopped. No smoking Also bear in mind the surface temperature of adjacent machines etc - although the auto ignition temp of propane is circa 460 deg C and butane 370 deg C so many normal machines are unlikely to have exposed surfaces at this sort of temperature If you apply the formula from BS60079-10, you can calculate the theoretical LEL distance from the source of release
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 2 users thanked Ian Bell2 for this useful post.
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Rank: Forum user
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Thanks so much for your response! That's incredibly helpful.
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Rank: Forum user
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Although we have fixed LEV, does anyone know of any small, portable LEVs which we could use for aerosols? Is there even such a thing I wonder.
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Rank: Super forum user
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If you had asked this 25 years ago, when I was still working in aerosol R&D, I would have known this off the top of my head. Ian Bell2 is largely correct in his descriptions. LPG propelled aerosols use propane and butane (usually mixed) as a propellent. The head pressure for Propane is 110psi at 20 centigrade and Butane is 30psi at 20c. The most common Propane/Butane mix is 40psi at 20c. Whether an aerosol is classified 'Extremly Flammable' normally largely depends on the amount of Propane in the propellent mix and proportionally how much prepellent there is in relation to the product. However, it is also affected by the solvent used in the actual product.
For instance WD40 is classified as 'Extremely Flammable' and has been propelled by Carbon Dioxide since the mid 1990's (I worked on the conversion from Propane/Butane).
How the classification is derived is not really directly from the theoretical propellent & product characteristics but more how the particular product performs (at least that's how it used to be done). There was a specific test for the classification that used to involve trying to ignite the product in a set volume of space with a naked flame (usually a candle in a modified oil drum). Hours of endless fun! The best organisation to go to for advice of the kind the markeland is looking for is probably The British Aerosol Manufacturers Association (BAMA) - Coincidentally, the current Vice-Chair was my old boss during the WD40 conversion work. However, the separation distance could be largely dependent on the specific product. Many brake/clutch cleaner aerosols can propel a highly volotile solvent a distance way beyond 750mm. Edited by user 10 December 2020 10:49:59(UTC)
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2 users thanked Holliday42333 for this useful post.
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