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Subject: [DCHAS-L] CSB Releases AB Specialty Silicones Factual Update
Date: Wednesday, December 18, 2019 at 12:10:24 PM
Author: Ralph Stuart <membership**At_Symbol_Here**DCHAS.ORG> 		Next by Date:
Subject: Re: [DCHAS-L] flammable hazardous waste
Date: Wed, 18 Dec 2019 14:54:00 -0500
Author: James Kaufman

From: Daniel Crowl <crowl**At_Symbol_Here**MTU.EDU>
Subject: Re: [DCHAS-L] flammable hazardous waste
Date: Wed, 18 Dec 2019 10:34:22 -0700
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**PRINCETON.EDU>
Message-ID: CAPEgXxzEs6P6nEcugCQFBoywH5QG4qgMvN0oTwRioMpJd5OQbA**At_Symbol_Here**mail.gmail.com
In-Reply-To


Hi Melissa,

The storage of flammable materials is a subject which is beyond the scope of this email list - the decision flowchart for this is really complex. To make matters worse, there is a lot of information out there that is absolutely wrong. Some topics continue to be debated by experts.

I can make a few general comments:

1. The decision flowchart depends on the conductivity of the material, its flammability properties, the nature of the area surrounding the container, and the conductivity of the container, to name a few.
2. It is not possible to ground a non-conductive container since the electrons cannot move easily thru the material. Plastic can be made conductive by additives - but it usually looks the same as non-conductive plastic. For this reason a lot of chemical plants do not allow any plastic containers or other plastic materials within a plant processing flammable materials.
3. Non-conductive materials are unlikely to produce a spark since the electrons cannot migrate thru the material to form a spark. However, a spark can be generated from a conductive liquid within a non-conductive container.
4. An ungrounded metal container is more hazardous than an ungrounded non-conductive container since a spark can easily form from the metal container and not likely from the non-conductive container.
5. A grounded metal container is the least hazardous since the charge is readily drained away by the grounding system.
6. Static electricity can be easily generated by pouring or flowing - particularly if the material is non-conductive. This can occur with liquids and powders.
7. Suitable grounding is another complex problem and flowchart. I am aware of some facilities spending more than $20K on their grounding system with considerable engineering. The system also needs to be tested regularly. The testing procedure and equipment is complex.
8. There is no well-defined "safe" boundary between conductive and non-conductive materials. It depends on charge accumulation and dissipation.

Dispensing gasoline into a metal container that is sitting on the non-conductive plastic bed liner of a pick-up is likely to cause a spark from the container to the grounded gas pump nozzle with a good possibility of a fire. Fires of this type have occurred many times at gas stations.

If you stick a grounding rod into a non-conductive container with a conductive liquid a spark might jump from the liquid to the grounding rod. This might cause a fire if the vapor within the container is flammable.

This subject is always a major issue with chemical plants handling flammable materials. This requires major expertise and engineering to resolve.

Dan Crowl, PhD, CCPSC
Adjunct Professor, University of Utah
Emeritus Professor, Michigan Tech University





On Wed, Dec 18, 2019 at 4:45 AM Melissa Ballard <melissa.ballard**At_Symbol_Here**michelin.com> wrote:

I would appreciate your feedback on my situation. We have recently replaced our single satellite accumulation container that was a 5-gallon metal drum to 2 separate plastic (UN approved) translucent "drums". This was at the suggestion of one of the environmental coordinators at the site. Now the other environmental coordinator & the "fire guy" are saying this is unacceptable because we cannot ground the plastic containers. We only use glass beakers or flasks to pour waste into these containers or it is waste going directly into a container from a HPLC (essentially a closed system).

Is this really a "fire risk"? I recognize that there may be a small potential for static to build in a plastic container, but we are not really "transferring or dispensing" from these containers in the traditional sense. The original starting materials are purchased in plastic 4L containers or glass containers which cannot be grounded when pouring out of either. I am having a hard time understanding the push to go back to a metal container just so we can ground it. I will add that the plastic gives us the ability to see the volume of liquid in the container so we will not over-fill it.

Thoughts on how to handle this? The plastic containers meet the requirements for the waste as per NFPA/DOT so it is just a question of fire risk.

Thanks for your input!

Melissa BALLARD - MSPH, CIH, CSP, CCHO

Industrial Hygienist / Industrial Hygiene Chemist

melissa.ballard**At_Symbol_Here**michelin.com

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