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Previous by Date: Subject: Re: [DCHAS-L] Auto-ignition temperatures Date: Tuesday, September 11, 2018 at 1:11:39 PM Author: Russell Vernon <russellnvernon**At_Symbol_Here**gmail.com> |
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Greetings,
A MIT a number of us were struggling with questions such as
Are metal powders flammable? Pyrophoric? What is the particle-size dependence of these properties? What about coatings, or oxides, or humidity? If a material could ignite at
6 minutes but not at 5, does that mean it shouldn't be handled like a reactive?
The answers, as always, are "it depends" but a website with some guidance was developed. Key credit for this goes to Mary Lindstrom, Iraj Aalaei, and Whitney Hess with input
from many others. The website includes the statement "Many metal powders present special storage and handling concerns when finely divided, including hazards such as air- or water-reactivity or explosive dust generation. Whether a given metal powder exhibits
these properties depends on multiple factors, including but not limited to particle size, surface area, moisture level, purity, etc."
The full webpage should be viewable here:
https://ehs.mit.edu/site/laboratory-safety/pyrophoric-and-water-reactive-chemical-safety . The statement "it depends" still applies but hopefully some may find this helpful.
Thanks
Dan
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU>
On Behalf Of Russell Vernon
Sent: Tuesday, September 11, 2018 1:12 PM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: Re: [DCHAS-L] Auto-ignition temperatures
Dear Tilak,
You have illustrated my concern about the removal of useful information in the name of GHS brilliantly.
Prior to GHS what was the criteria that an MSDS used to declare a substance pyrophoric? The fire code definition that uses autoignition temperature (equal to or less than 130F).
The GHS definition for H250 :
Chapter 2.9, Pyrophoric liquids - indicate whether spontaneous ignition or charring of the filter paper occurs, generally determined by Test N.3 (section 33.3.1.5 of the Manual of Tests and Criteria)
Chapter 2.10. Pyrophoric solids - indicate whether spontaneous ignition occurs when poured or within five minutes therafter, generally determined by Test N.2 (section 33.3.1.4 of the Manual of Tests and Criteria)
The US adoption of the GHS definition is codified at: https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1200AppB and is:
B.9 PYROPHORIC LIQUIDS
B.9.1 Definition
Pyrophoric liquid means a liquid which, even in small quantities, is liable to ignite within five minutes after coming into contact with air.
...
B.10 PYROPHORIC SOLIDS
B.10.1 Definition
Pyrophoric solid means a solid which, even in small quantities, is liable to ignite within five minutes after coming into contact with air.
so H250 now includes water reactives in addition to real pyrophoric materials
-Russ
russellnvernon**At_Symbol_Here**gmail.com
On Tue, Sep 11, 2018 at 8:21 AM TILAK CHANDRA <0000058f112ac338-dmarc-request**At_Symbol_Here**lists.princeton.edu> wrote:
From Sigma-Aldrich SDS:
GHS Label elements, including precautionary statements Pictogram Signal word Danger Hazard statement(s)
H250 Catches fire spontaneously if exposed to air.
H261 In contact with water releases flammable gases. Precautionary statement(s)
P210 Keep away from heat/sparks/open flames/hot surfaces. No smoking.
P222 Do not allow contact with air. P223 Do not allow contact with water. P231 + P232 Handle under inert gas. Protect from moisture. P280 Wear protective gloves/ eye protection/ face protection. P335 + P334 Brush off loose particles from skin. Immerse in cool water/ wrap in wet bandages.
Tilak
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU> On Behalf Of Jeffrey Lewin
Sent: Tuesday, September 11, 2018 9:42 AM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: Re: [DCHAS-L] Auto-ignition temperatures
The Alcoa GHS SDS I have for aluminum powder lists:
Product identifier ATOMIZED ALUMINUM POWDER
Auto-ignition temperature 1202 ¡F (650 ¡C) layered
Hazard statement May form combustible dust concentrations in air.
However, they also list DOT as not regulated.
The DOT Hazard Material Table lists:
Aluminum powder, coated as DOT 4.1 (Flammable Solid)
Aluminum powder, uncoated as DOT 4.3 (Dangerous when wet)
Jeff
On Tue, Sep 11, 2018 at 5:34 AM Debbie M. Decker <dmdecker**At_Symbol_Here**ucdavis.edu> wrote:
Hi All:
We're working through a list of materials classified as H250 (pyrophoric) but are having a terrible time finding auto-ignition data to back up that classification. It appears to have evaporated off Sigma SDS' and other sources (CRC, PubChem, ChemSpider, CAMEO) don't seem to have it either. Most irritating, to me, is the classification of powdered aluminum as pyrophoric with no auto-ignition data to back it up - just a note "ignites on contact with air." If that were the case, the entire pyrotechnic and propellant industries would have folded up by now.
Does anyone out there have auto-ignition data in a format they're able/willing to share? Or have any insight into where the data has gone off to?
Thanks mucho,
Debbie
Debbie M. Decker, CCHO, ACS Fellow
Past Chair, Division of Chemical Health and Safety
Councilor and Programming Co-Chair
University of California, Davis
dmdecker**At_Symbol_Here**ucdavis.edu
Birkett's hypothesis: "Any chemical reaction
that proceeds smoothly under normal conditions,
can proceed violently in the presence of an idiot."
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--
Jeff Lewin
Chemical Safety Officer
Compliance, Integrity, and Safety
Environmental Health and Safety
Michigan Technological University
Houghton, MI 49931
O 906-487.3153
--- For more information about the DCHAS-L e-mail list, contact the Divisional membership chair at membership**At_Symbol_Here**dchas.org Follow us on Twitter **At_Symbol_Here**acsdchas
--- For more information about the DCHAS-L e-mail list, contact the Divisional membership chair at membership**At_Symbol_Here**dchas.org Follow us on Twitter **At_Symbol_Here**acsdchas
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