By TJ Frawley, Project Manager, Flammability Testing & Consulting Services
On April 7th the Director of the National Institute of Allergy and Infectious Diseases for the past 36 years entered the sound studio using his shoulder to nudge open the door, very deliberately not touching the handle. He walked over to the chair in front of the microphone and, using his foot to scoot the legs back far enough, sat down. He inched closer to the desk. But upon seeing the microphone was out of position, and lacking any way to adjust it, he reached out with his hand and positioned it, so he could be heard.
Once settled in, the NIAID director immediately rummaged through his pockets and produced a portable bottle of hand sanitizer. He applied more than a dab but less than a palm-size pool and proceeded to rigorously rub the sanitizer into his hands. It was the first contact with anything or anyone he had made using his hands since stepping out of his car.
“When you gradually come back, you don’t jump into it with both feet,” Dr. Anthony Fauci told podcast host Kate Linebaugh on The Journal. “You say, what are the things you could still do and still approach normal? One of them is absolute compulsive hand-washing.”
Health experts have repeatedly urged the public to practice good hand hygiene since the coronavirus outbreak began. The WHO advises washing hands “regularly and thoroughly” with soap and water or an alcohol-based hand rub if soap is not accessible. And people are listening. According to an article from cbsnews.com, “Demand for hand sanitizers has spiked 1,400% from December to January.”
But in this ambiguous era of personal and public health, applying hand sanitizer is not as simple as one may think. It is important to consider and follow hand sanitizer safety guidance because failing to do so could either lead to infection or, in the case of an unfortunate Oil & Gas worker, first and second-degree burns.
Most alcohol-based hand sanitizers contain varying amounts of isopropyl alcohol (IPA). The recommended concentration of IPA for hand sanitizers to effectively neutralize the Coronavirus is approximately 75% to 80%.
IPA has an evaporation rate approximately 7.7 times that of water, which is very quick. Additionally, the vapor density of IPA is 2.1 times that of air, making it relatively heavy. To put it succinctly, IPA not only evaporates quickly, but those vapors have a tendency to gather and linger.
The flammability characteristics of IPA are telling of its hazards. IPA has a lower flammable limit (LFL) of 2.0% and a flash point of 54°F. When we put all this data together we find ourselves with an easily and rapidly created flammable cloud. The only thing left to do is find an ignition source to set the whole thing ablaze.
And as fate would have it, IPA vapors are easily ignitable. We can demonstrate this by testing for IPA’s minimum ignition energy (MIE). The MIE is the smallest amount of energy needed to “kick start” a reaction and is measured in millijoules (mJ). A small static shock that can be felt is roughly 20 - 30 mJ. The minimum ignition energy of IPA measures much lower, at just 0.65 mJ.
What we have at hand on our hands is a flammable and easily ignitable vapor cloud.
Luckily there are other factors, such as humidity and air flow, which minimize the risk of the hazards and reduces the probability of a fire ball on your hands. But minimizing the risk isn’t eliminating risk. Take the aforementioned O&G worker for instance. He applied an alcohol-based sanitizer to his hands and touched a metal surface before all the flammable vapors had a chance to dissipate. Due to a static shock from touching the metal, the vapor cloud ignited, engulfing both his hands in flames.
Making matters more terrifying, the flames were nearly invisible to the naked eye. As his hands were burning he likely could not see what was happening but could certainly feel the intense heat and pain.
To prevent this type of accident you should touch a conductive surface immediately BEFORE applying hand sanitizer. This will dissipate any built-up charge and prevent static shocks. Also, do not touch anything else until the alcohol from the sanitizer completely evaporates.
Flammability and explosion data for isopropyl alcohol and a multitude of other chemicals (everything from corn dust to decamethyltetrasiloxane) can be obtained from Fauske and Associates LLC. For any testing inquiries or consultation please contact us to get your questions answered.