This story is included in the inaugural 2021 edition of Safety Partners’ publication, “Incidents, Accidents, and Near Misses in Laboratory Research.”
When you perform fermentation, the cells produce acid that decreases the pH of the system. Conversely, sometimes the cells will eat acid in specific processes, making the whole system more basic. The consistency and quality of your product are very dependent on having a stable pH, so you must add acid or base as you go.
At my workplace, the addition of acid or base is accomplished via two ports, one for each, set up in a standardized process. These lines need to be primed with acid or base so that when you need either, they are ready to go. When necessary, we open the entire line to the tank and start pumping at a very slow rate. When the pH begins to change slightly, we end the pumping and close off the lines. Pretty simple, right?
Under Pressure
Well, the automation process is designed to make it even easier. However, there was a snag in the process; the valve to open the acid line to the tank was manual and could not be automated.
The workers forgot to open the valve up under the assumption it was taken care of. After they finished priming the lines, all of that acid was hitting the closed valve again and again, building up pressure.
Now, this would be a problem in any case, but the way the tubing was connected to the valve that day complicated things further. You see, the plastic tubing of the line is usually secured to the stainless steel of the valve by a zip-tie.
The employees working that day, unfortunately, did not have any zip-ties and left it as is. Since it wasn’t secured, the pressure popped the tubing and liters of 15% phosphoric acid proceeded to spray everywhere.
The acid jettisoned 20 feet in the air and splashed on 2 of the people working the line. The workers ended up needing to see occupational health and the incident was OSHA recordable. Thankfully, these two were not gravely injured and made a full recovery. The floor, however, was left with an indelible orange mark of the debacle that occurred. I like to think that it served as a reminder to take the time to do the job right.
Part 2: Another Incident
Unfortunately, that lesson wasn’t learned by everyone, because there was another incident within a few months where creative, but improper clamping of a line, led to a spill.
After fermentation is done, there is normally a decent amount of acid or base remaining in the line that is worth holding onto to save a buck. Our company took this money-saving approach a step further by reusing the container, the tubing, and valve. We’d keep these set off to the side for use on the next process because valves tend to be a hot commodity in my line of work. Saving money on tubing is also a plus.
The standard operating procedure is to put an end cap on the line when you remove a valve. This time that didn’t happen. Instead, my coworkers, Sam and Ellie, the creative problem solvers they were, discovered that you could close the line pretty tight using forceps like the ones they use at the doctor’s office. For a while, it was effective and kept the phosphoric acid safely in the line even when it was primed.
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