Hi Peter

It’s a pity you didn’t state the liquid in question.

First the LEL and UEL are not always in section 9 of a safety data sheet they are sometime is the firefighting section in section 4.

Also some safety data sheets might just state Not Determined. This is where you can sometimes find the information by looking in the safety data sheet at the overall CAS Number for the substance (if it is a pure liquid and not a mix). Or the CAS number for the flammable components which are give as percentages in the mixture and identify the lowest LFL properties by referring to the list off CAS Numbers and their properties within BSEN 60079-20 (but unfortunately not all substances appear there).

Another reason for it not to be listed is some cases on the safety data sheet is if the flash point of the liquid is above 60⁰C then it is considered as combustible and not flammable which is why sometimes there is no LEF or UEL on the safety data sheet.

As I am sure you are aware the flash point is the minimum temperature at which the liquid gives off vapours in sufficient quantity to become ignitable.

So if the liquid is being handled (Spilt) at or above its flash point or onto a surface which might increase its temperature to such a point then there might be a risk.

As outlined by John you can 'back track' a substance by looking at its composition and then using BS60079-20 for the material DSEAR properties.

Yes, you can assume the material you have is non flammable, it is not classified on the MSDS - no flamamble symbol/category for DSEAR purposes for the most part/most situations.

Sometimes people go further, if for example you are using a lot of the substance in your facility and/or you have some odd process conditions in terms of temperatures/pressures etc Maybe your facility is particularly high value/vital to company operations. You then might want to commission further chemical testing and analysis to determine the material properties. This is wider process safety rather than DSEAR. I've seen this done in the defence sector, where there are very high asset value equipment/platforms present and the consequnces are very high in the event of an accident.

DSEAR assumes that your process conditions/workplace are in the range of -20 to +40*C and 0.8 to 1.1bar atmospheric pressure.

Originally Posted by: peterforan87

I'm trying to determine whether an explosive atmosphere would form from a spillage of a flammable liquid

Between the OP and the additional information in post 3 that the flammable substance contained within the mixture was <2.9% of the total this design flaw with the layout of Safety Data Sheets seems to persistently catch out readers.

Section 2 gives the classification of what is being purchased in the tin, bottle, tube, can etc. and where the product is a 100% pure substance the classification in Section 2 and Section 3 will be identical.

For a mixture Section 3 classifies the constituents as though they are pure substances (the "flammable" component mentioned) however this will differ in Section 2 where the overall product classification will be based upon all its constituents - at <2.9% is unlikely to be a flammable liquid (97% not classified such).

Recommended reading is the ECHA guidance document on preparing a Safety Data Sheet

https://echa.europa.eu/documents/10162/2324906/sds_en.pdf/01c29e23-2cbe-49c0-aca7-72f22e101e20

Originally Posted by: Roundtuit

Originally Posted by: peterforan87

I'm trying to determine whether an explosive atmosphere would form from a spillage of a flammable liquid

Between the OP and the additional information in post 3 that the flammable substance contained within the mixture was <2.9% of the total this design flaw with the layout of Safety Data Sheets seems to persistently catch out readers.

Section 2 gives the classification of what is being purchased in the tin, bottle, tube, can etc. and where the product is a 100% pure substance the classification in Section 2 and Section 3 will be identical.

For a mixture Section 3 classifies the constituents as though they are pure substances (the "flammable" component mentioned) however this will differ in Section 2 where the overall product classification will be based upon all its constituents - at <2.9% is unlikely to be a flammable liquid (97% not classified such).

Recommended reading is the ECHA guidance document on preparing a Safety Data Sheet

https://echa.europa.eu/documents/10162/2324906/sds_en.pdf/01c29e23-2cbe-49c0-aca7-72f22e101e20

So my logic is sound with regards to the content of the mixture and its level of risk? (i.e. disregard the hazard classfication symbol in section 2 due to the compostion of flammable parts being < 2.9 % of the total?)

I take it that section 2 of the sheet requires the hazard symbol to be present even if the flammable content of pure ingredients in the mixture is negligible?

Peterforan87

The flammable symbol is there for a reason and shouldn’t be ignored it all depends on what is going on in regards to volume of substance and room, temperature, and flash point and available ventilation and what you are doing with it. Your could be runing it through a still for all they know to collect the flammavle substance alone.

Lets assume that you have a 205litre drum of your flavouring which leaks into a bund deep enough to contain all the leaked liquid with a surface area of 6m².

Your flammable percentage is 2.9% of the 205litres which is 5.945litres.

If the flammable substance is lighter that the rest of the products making up the mixture it will float upon the surface of the liquid within the bund. This will give you a flammable substance 6m² which is 1mm deep floating on top of the liquid which could become ignited and burn if the temperature is within its flash point range. (Not necessarily explode).

 It will burn until all the liquid that is flammable has evaporated off or the fire is put out.

Therefore, if you assumed your flammable element of the liquid was ethanol (which I know it isn’t as the LEL for ethanol is 3.3%) using BSEN 60079-10-1 Evaporating pool formula the would give you a evaporation rate of 7.5E-09 Kg/s

If this bund was in the middle of the floor off a room which was in a room 10m(L) x 10m(w) x 2.5m(H) giving a volume of 250m² and assuming it had no mechanical ventilation or natural ventilation grilles. But was ventilated purely by gaps in the structure of the building giving fortuitous ventilation of 1.5 air changes per hour, based upon the old BS 5345 Part 2 table for single story non partitioned spaces, brick or concrete construction up to 300m³. This would give you a 0.069m³/sec ventilation rate.

You now have when you know what you are doing have a hazardous zone with a hazardous Volume (Vz) off (6.8E-06 m³) and due to the ventilation rate your background concentration (Xb) for the room would be 5.79E-05 Vol/Vol so negligible extent.

This is to give you a comparison to help visualise against and is not the calculation your site.

I have not shown all the formulas and workings to give me these findings deliberately, as if everyone could work the dark arts of DSEAR then there would be no longer any mystery left in the world.

Not only the USA - CHiP https://www.legislation.gov.uk/uksi/1994/3247/schedule/5/made

The safety data sheet referred to in regulation 6 shall contain the following obligatory headings: 2. Composition/information on ingredients. 3. Hazards identification

It was REACH and subsequent enabling regulations that "switched" the order

SECTION 2: Hazards identification 2.1. Classification of the substance or mixture 2.2. Label elements 2.3. Other hazards

SECTION 3: Composition/information on ingredients 3.1. Substances 3.2. Mixture

The flammable ingredient wouldn't be floating on top if it is dissolved in water.

Originally Posted by: Kate

The flammable ingredient wouldn't be floating on top if it is dissolved in water.

You cannot disolve a liquid in a liquid only powders  you can dilute it and it didnt state what the flammable element was in this instance. There are substances that can settle out into their specific gravities and visible layers  both as a liquid/liquid mixtuer or liquid/powder mixture, which is why there is the instruction on some substances stating shake well before use. As I didn't know the exact makeup of the mixture i erred on the side of caution and give this as an example as to what can happen.

Edited by user 22 August 2023 07:28:21(UTC)  | Reason: spelling correction

Could the OP please state the content - as listed - in Section 2 of the SDS they have for the product as I would really like to appreciate what they are actually seeing.

....just to add it isn't always about the datasheet...the temperature and pressure also have a part to play....example everyone would say gaseous N2 is lighter than air...generally in industrial environments it is at a lower temperature making it slightly heavier..changes the way you look at the risk.

Chemical risk analysis - A practical apprach Berrnard Marel.  Is a good reference for how flammability, toxicity etc is determined.

Simple pool evaporation calcs can be found in:

https://www.aidic.it/cet/16/48/009.pdf