Rank: Forum user 
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How would you go about measuring the LEL for Benzene in a confined space. Is it still measured in parts per million. I read somewhere that the LEL for Benzene is 800ppm. However I have little experience in measurement or contact with this substance. any help will be greatly appreciated.
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Rank: Super forum user 
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You don't measure the LEL (lower explosive limit), you look it up (for example on a safety data sheet - it will be under physical properties).
What you might measure is the actual concentration of benzene to compare it with the LEL. You need a gadget for that and a trained person to operate it (without entering the confined space to do so).
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Rank: Forum user
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Kate wrote:You don't measure the LEL (lower explosive limit), you look it up (for example on a safety data sheet - it will be under physical properties).
What you might measure is the actual concentration of benzene to compare it with the LEL. You need a gadget for that and a trained person to operate it (without entering the confined space to do so). Thanks Kate, I could not get my head around the 800ppm as being an LEL...wish I could remember where I had read that, I'm sure it was an American safety page on the web.
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Rank: Forum user
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Hi Bluewater,
quite a specialist field this, be careful! The 8hr TWA Workplace Exposure Level for Benzene is 1ppm. Be aware that the limits in the UK and US are often very different.
Steve
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Rank: Super forum user 
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The 'gadget' Kate refers to being an explosimeter I believe.
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Rank: Forum user
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Rank: Forum user 
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Blue,
The LEL for benzene is 1.3%, which equates to approx. 13,000ppm. Modern flammable gas detection equipment is usually to set to alarm at a percentage of the LEL e.g. 10%. However, as already stated you do have to consider the WEL (workplace exposure limit) and this is significantly less than the LEL. So whilst the area might be safe because the LEL is not exceeded, workforce exposure would be well exceeded. Hope this helps.
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Rank: Super forum user 
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I believe that the WEL for Benzene is due to its "narcotic" properties; as it is a Carcinogen then you should be looking for going "ALARP" as regards exposure. When I used to manage entries like this we would vent and purge so that there were negligible levels of flammables and Benzene - and even then, we would use Breathing Apparatus for the entry. I would advise; use extreme caution and get competent, if not expert, advice. As soon as I saw "Benzene" and "Confined Space" in the same sentence, I took a deep breath.......................!!!
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Rank: Super forum user
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Rank: Forum user
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Rank: Forum user
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JohnMurray wrote:https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/316487/Benzene_guidance.pdf Thank you John.
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Rank: New forum user
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Rank: Super forum user 
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I'm not sure why you would want to measure anything relating to a Lower Explosive Limit, its usually in the % range of contamination whereas exposure is generally in the parts per million range. If you need to monitor flammable gasses / vapours in air say for confined space entry then you need a flammable gas/vapour monitor like this https://www.crowcon.com/...cts/portables.html - other brands are of course available and you need to select one that does what you want it to do.
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