Yes, I agree. There are significant differences in gas LFL values between the US and Europe because of the test apparatus. The US is always lower due to the smaller diameter tube used as well the requirement to see a flame propagation downward. In addition LFL for a pyrophoric gas is a significant challenge due to ignition while it is being introduced and prior to mixing.
In recent testing on disilane we had to use a special test apparatus that was custom designed for silane testing to determine the LFL. This was summarized in a recent article
Nguyen, T. T. ,Cao, K. Q., Yang, M. H., Chen, J.R , Tsai, H.Y., Gordon, M., Ngai, E., "Experimental Studies on Ignition Behavior of Pure Disilane and Its Lower Flammability Limit", CHEMICAL ENGINEERING TRANSACTIONS, VOL. 90, 2022
Eugene Ngai
Chemically Speaking LLC
www.chemicallyspeakingllc.com
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> On Behalf Of Daniel Crowl
Sent: Thursday, January 27, 2022 10:50 AM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Subject: Re: [DCHAS-L] Chemical Safety headlines (10 articles)
One needs to realize that the flammability "properties" of chemicals are not fundamental properties such as density, heat capacity, etc.
They are only values derived from a particular apparatus and procedure. This includes flammable limits, flashpoint temperatures, ignition energies and AITs.
Thus, one needs to be careful in applying these "properties" to real situations.
The AIT values for dusts are empirically derived from an apparatus that suspends the dust in air - not dust piles.
Thus, it is not clear how the AIT applies to the sulfur dust piles.
Photos from other news sources (but nothing spectacular)
The autoignition temp is probably related, but I wouldn't know how. Most deflagration accidents have occurred at ordinary outdoor/indoor temperatures. For deflagration the most relevant data is the deflagration index (Kst) value which is dependent in part on particle size. We are now requiring Kst values for special effects dusts used in entertainment venues. It's an expensive test, but once it's determined, the data can go right on the SDS for all future customers.
There was an interesting deflagration of walnut shell dust thrown into the air to look like conditions after a mine collapse on a set in 2003. The set was in a major arena and the deflagration and subsequent fire did $5 Million in damage. That'll teach them to rent out to a film company.
This Kst value is another bit of data that should be on all SDSs for anything in powder form. It would be easy in the case of inert minerals because the Kst would be zero since they can't deflagrate. But powdered sugar, starch, dyes, or any other organic chemical powder or metal powder in bulk should be accompanied by a Kst value. Some of the metals, like aluminum, have a particularly nasty punch, and we've seen these go off even when aluminum pigment powders were transferred from container to container where friction causes a static discharge as the initiator.
So I teach about deflagration with containment such as wood shop explosions where the building collapses, and deflagration without containment which there is a flash over and subsequent fire such as the Holi powder (starch and dye powder) flashover and fire in the Tiawan pool party fire that put over 500 in the hospital and killed 15.
And now, thanks to Ralph, I have a sulfur example. The pictures, of course, are no fun, since the warehouse was not closed up and it didn't explode. The best I can do is show a picture of the fire trucks and wisps of smoke coming out of the warehouse from the pile of sulfur that the flash over set on fire.
So Ralph, get one with a mushroom cloud and flames next time, OK?
-----Original Message-----
From: davivid <davivid**At_Symbol_Here**WELL.COM>
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Sent: Wed, Jan 26, 2022 2:52 pm
Subject: Re: [DCHAS-L] Chemical Safety headlines (10 articles)
Turns out the reported autoignition temperature for sulfur is as low as
168C. The dust is quite sensitive and hydrocarbon impurities are known
to decrease the autoignition temp.
http://www.sulphuric-acid.com/techmanual/Plant_Safety/safety_sulphur.htm
This is lower than that of red phosphorus at 260C.
https://web.stanford.edu/dept/EHS/cgi-bin/lcst/lcss/lcss72.html
Regards
Dave Lane
Principal
Clavis Technology Development
On 1/26/22 7:45 AM, Monona Rossol wrote:
> At last. My ppt has examples of all kinds of deflagration substances, but I haven't had a good one on sulfur. Monona
> CAUSE DETERMINED OF SULFUR FIRE AT CERES FARM COMPANY
> https://www.modbee.com/news/local/article257699048.html
> Tags: us_CA, industrial, follow-up, environmental, ag_chems
>
> The source of a hazardous materials fire that prompted a 12-hour shelter in place advisory for some Ceres residents on Monday was determined to be a light bulb.
>
> An employee at Stanislaus Farm Supply on East Service Road was changing a light bulb inside a 40,000-square-foot warehouse that contained a large amount of fertilizer-grade sulfur, said Dustin Bruley, supervisor of the Stanislaus Regional Fire Investigation Unit.
>
> "In those warehouses they have a lot of dust floating in the air attributed to that product and when you change out a light bulb the simplest spark or static electricity can set off the particulate that floats in the air," Burley said. In this case the particulate was flammable sulfur.
>
> He said the spark caused flash fire, "The air around it has this matter floating so when it ignites, anything in that room has the potential to ignite as well."
>
> A 500-ton pile of fertilizer sulfur began smoldering. Employees tried to put it out but the fire grew larger than they could handle.
>
>
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