"doing a reaction is criminal. That's incredibly dangerous"

 

The importance of college and universities to our industry is obvious. Our industry’s emphasis on safety is someways opposite of that in some institutions of higher education. On our occasion we have reached out to universities and colleges when we saw a photo of their students in teachers in dangerous situations. The photos we have acted upon would simply not be tolerated in industry. But, I fear they are commonplace in institutions of higher learning. We stumbled upon this post, we do not know if the incident was recent or long ago. Nevertheless, we feel this incident can be a valuable learning tool for all readers.

A Campus Laboratory Fire Involving Lithium Aluminum Hydride

What happened?

In a fume hood, a researcher used 5 grams of LAH to conduct a reduction reaction of a synthetic compound dissolved in 100 mL of tetrahydrofuran (THF). The remaining LAH stock of 95 grams, in its original non-resealable plastic bag, was placed in the hood next to the reaction apparatus after the necessary material had been weighed. In the same hood, adjacent to the reduction reaction was an unrelated experiment involving pentane, a flammable solvent.

Minutes after start of the reaction, the reaction flask over-pressurized causing the flask septum to pop off, initiating a fire in the hood. Nearby researchers initially used a CO2 fire extinguisher, which spread the fire igniting the adjacent setup containing pentane. Other researchers then used Met-L-X®dry powder fire extinguishers to put out the hydride portion of the fire. Finally, a CO2 extinguisher was deployed to extinguish the remaining other fuel sources.

Smoke from the fire triggered the building smoke detectors and a full-building evacuation. As a result of the incident, several researchers reported smoke inhalation and laboratory damage was limited to one fume hood.

What was the cause of the incident?

The primary cause of the fire was the researcher’s incorrect determination of the LAH:THF ratio. This incorrect LAH:THF ratio led to a significant exotherm and the rapid release of gas (H2) and solvent from the reaction flask, initiating the fire.  Prior to the experiment, a thorough review of the experimental design had not been conducted.

 What should have been done differently?

Contributing factors that intensified the fire event included:

Additional fuel (open container of LAH, adjacent pentane experiment) was present in the hood.

The incorrect fire extinguisher (CO2) was initially used to attempt to extinguish the LAH fire. This action may have contributed to the spreading of the fire to an adjacent pentane setup, possibly adding to the initial fire danger

How can incidents like this be prevented?

Review of Standard Operating Procedure (SOP)

Prior to beginning work with LAH and other metal hydrides, ensure an SOP is written and reviewed. The PI is to assure that SOP review accounts for details including but not limited to:

Experimental details (i.e., material selection, reaction concentration, scale of reaction, etc.)

Identification and control of potential hazards (i.e., fume hood use, PPE, etc.)

Special emergency procedures (i.e., response for metal fires)

For SOP guidance and an SOP template, refer to (we deleted the link to the school’s ehs page)

See the general use SOP on highly reactive/unstable materials.

General Handling and Storage of Lithium Aluminum Hydride

Handle LAH and other pyrophorics under an inert atmosphere, within a glove box, fume hood, or equivalent.

Keep and store away from heat/flame, oxidizers, acids, and moisture/water sources.  For storing LAH, keep sealed under an inert atmosphere.

Learn more by reading about (college name omitted) Storage Groups.

Relocating/Removing of Adjacent Research Experiments

Where LAH and other pyrophorics are used, keep the immediate work area clear of un-related experiments containing combustible/flammable materials as well as unused LAH and solvents, lab notebooks, and other non-essential combustible/flammable items. 

Appropriate Fire Extinguisher Use

For use of LAH and other metal hydrides, ensure Met-L-X® dry powder fire extinguishers are identified as the extinguishers for metal hydride fires, and clarify this detail in each associated SOP.For assistance with selection and provision of fire extinguishers, contact the (college name removed) University Fire Marshal’s Office at .

To assure adequate awareness exists on proper fire extinguisher use:

EH&S will review existing training materials for additional opportunity to emphasize above items.

Groups using LAH or other pyrophoric materials are recommended to obtain periodic refresher training on proper use of fire extinguishers.

Appropriate PPE

When working with LAH or other pyrophoric materials, at minimum, a flame-resistant laboratory coat is required, along with protective eyewear, and gloves. NOTE: Nomex and related aramid fiber products are flame-resistant materials, but pose dexterity concerns when used as hand protection. Where hand protection from flammability hazards is required, flame-resistant gloves such as Nomex flight gloves are to be worn on top of gloves providing adequate chemical protection.

Emergency Response

In case of a fire emergency, ensure prompt reporting by completing the following actions:

Pull the nearest fire alarm pull station to activate the building-wide fire alarm system.

Call 9-911 to report and describe the incident so emergency responders can be updated regarding current conditions while en route.

So we are glad no one was injured in this incident. They were lucky. If the flask septum (rubber stopper) did not come off the glass container would have exploded throwing glass throughout the room, unless the door to the testing was closed.

Now let us step on our soapbox. We have viewed so many photos and videos showing university students and professors that would make one gasp. We have reached out to several department heads and professors and explained to them what we had viewed could have killed those in the photo or seriously injured them. There was a period of time that the Aluminium Plant Safety Blog would post an incident in an educational setting (college, art, high school) once every six months. A number of years ago the editors sat on a safety committee of an industry backed organization. We take with pride that we were able to educate the others on this safety group about molten metal explosions. It was because of lectures that we were able to change the instructions that the organization included with the small molds that they sent out to high school teachers. There was an incident in North America where a dozen students were injured in a molten metal explosion. We believe it was because they did not preheat the molds. It was this incident we brought forth to the organization and they included the language to pre-heat the molds prior to demonstrating to the student molten metal. We had forgotten about that matter. It was only this incident that brought it back to our memory. If we do nothing else, we are glad that because our involvement high school students are safer. That is why we do this blog. 

A friend was surprised that we are approaching our 10th anniversary on the blog. We were asked "what is the blog about?" We responded "death". My dear wife said that my answer was overdramatic. But in all honesty, my answer is correct. This blog is about death. Preventing death. Our friend ask if we liked doing it after 9+ years. We responded that this blog is the hardest thing we do. Why, was asked? Because we know of all the sadness and pain associated with an injury or fatality. It is this sadness and pain that propels us forward. We simply want no one to be injured or killed in a workplace accident. So we continue posting, and pray that there will be a day that we have nothing to post.

UPDATE

We have a number of contacts throughout the industry who were are honored to call friend. It is these people who we have learned so much from. These people have been so very kind to respond to our questions. It was one of these contacts that we sent this incident to with the question "Can you explain this incident to me?" Here is my friend's response. 

Hi (name omitted)! Without knowing the actual compound that was being reduced, it's difficult to have an exact answer, but the most likely scenario is that there was an acidic proton source (on the compound being reduced, or maybe water in the THF if it hadn't been purified). LAH will pull off those protons and make dihydrogen in an exothermic reaction. So, heat builds up the pressure in the reaction flask, a (probably) unsecured septum gets blown off, and now you have dihyrogen and heat reacting with the dioxygen in the air: Fire! Both the THF and the nearby pentane are very flammable, and any water that forms from the H2 + O2 reaction can drop into the remaining 95g of LAH and have it go off, as well.

Leaving 95g of LAH open to the atmosphere while doing a reaction is criminal. That's incredibly dangerous, 95g is a LOT of LAH!

That could have been disastrous.

The other mistake was to use a CO2 extinguisher. Those should never be used with metal fires, as the metal can react with the CO2 and get oxidized. This makes more heat and allows the fire to continue.

Please comment.