Ethyl Acrylate: The Stink That Announces Itself Long Before It Hurts You
Ethyl acrylate is a colorless liquid with what is charitably called an acrid, penetrating odor and less charitably called one of the most offensive smells in industrial chemistry. Its odor threshold is extraordinarily low, well below a part per billion for many people, which means you will smell it long before it reaches a harmful concentration. That’s a rare gift in this business, and also the reason a small leak can generate a very large number of angry phone calls.
It’s a building block monomer for acrylic polymers, showing up in paints and coatings, adhesives, caulks, textile and paper finishes, and latex products. It’s a flammable liquid with a flash point around 60 degrees Fahrenheit, so at normal summer temperatures it’s already giving off an ignitable vapor. It’s also a strong irritant to eyes, skin, and the respiratory tract, and a known skin sensitizer, meaning a worker who has been exposed once can react much more strongly to a small exposure later.
The hazard that actually destroys containers is polymerization. Ethyl acrylate wants to link up with itself, and that reaction is strongly exothermic and self-accelerating: the hotter it gets, the faster it goes, and the faster it goes, the hotter it gets. Shippers keep it stable with an inhibitor such as MEHQ, and here’s the detail that surprises people, that inhibitor requires dissolved oxygen to function. Blanketing a tank with nitrogen, the instinctive move for a flammable liquid, can actually disarm the very thing keeping it calm. Heat, contamination, or aged inhibitor can set off a runaway that ruptures a drum or a rail car.
Whether you’re at a polymer plant, a coatings warehouse, or a tank car exposed to fire, remember that this one has two clocks running: the fire clock and the polymerization clock. Approach upwind with SCBA and vapor protection, eliminate ignition sources, and if a container is heating, get people out of the endpoints of the vessel and cool it from a distance with unmanned appliances rather than sending crews in close. Ask the shipper about inhibitor status and temperature history early, because a container that has been hot for a while may already be past the point where cooling saves it.
Have fun and let us know how you did in researching the hazards.
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About the Author:
Dave Donohue is a hazardous materials course developer, educator, and trainer with experience at the local, regional and national level. He is also a Master Exercise Practitioner, firefighter, and emergency manager.
