It’s been a while since I did a True Lab Story, and it seems like an appropriate sort of topic for a rainy Friday when I have grades to finish. I’m running out of really good personal anecdotes, but there are still a few left before I have to move entirely to hearsay. And who knows, maybe I’ll break something in spectacular fashion between now and then…
Anyway, lab safety offices are a rich source of True Lab Stories. Not just because they have to clean up from the really spectacular disasters, but also because their desire to prevent disasters sometimes leads to inflexible applications of policies that make little scientific sense. This tends to butt up against the natural inclination of scientists to do whatever they damn well please (if we were good at conforming to rules, we’d get more dates), which occasionally produces amusing results.
The best clash between lab safety officials and physicists that I personally witnessed was probably the Great Nitrogen Spill of 1996.
The various experiments in the Physics lab at NIST consume a great deal of liquid nitrogen for one purpose or another, so there is a large liquid nitrogen storage tank in the basement at one end of the building. At least once a week (I think it may have been twice a week), a tanker truck backs up to the loading dock, and they top off the tank. (They also refill a bunch of smaller but still substantial rolling tanks, that are distributed to the individual labs.)
One Friday when I was in grad school, they showed up to fill the tank, but somehow, a valve got left open, and the liquid was gushing out onto the floor of a service room in the basement. The liquid boiled, of course, filling the room with nitrogen vapor, and eventually, it tripped the low oxygen sensor in that room. Which triggered the evacuation alarm for the entire building.
So, a hundred-odd physicists shuffle their way outside, and start milling around, wondering what the alarm is for. Eventually, word gets around that it’s a liquid nitrogen spill in the basement, and they react as you would expect physicists to react: they shrug, and head back to work.
Nitrogen is pretty harmless, after all, and while you might suffocate if you happened to be in the basement room where the spill occurred, or possibly one of the adjacent lab modules, an excess of nitrogen in the basement poses no real threat to a theorist with a third-floor office. So, despite the alarms and flashing lights, people started heading back into the building (how they planned to get anything done was beyond me– the alarms were really annoying).
Of course, by this time, the lab police and fire department had arrived, and they weren’t too happy with this turn of events. So they chased people back out, and posted guards at the entrances to the building. Which again, was met with a shrug– the people with second- and third-floor offices just went into the engineering lab next door, went up to the second floor, and crossed over the connecting hallway. Which, of course, led to another round of evictions, and the posting of guards on the second and third floors of the adjacent lab buildings as well.
Meanwhile, another group of scientists decided to try to convince the fire department to ease up, and turn the alarms off, since the situation was basically under control. The fire chief was having none of this, leading to the quote that has become my mental tag for the whole incident: “It doesn’t take a rocket scientist to see what a dangerous situation this is!”
Sadly, they weren’t interested in the opinions of actual rocket scientists. They kept us standing around outside for a good forty-five minutes. We decided that they probably had a nitrogen detector, and were running around being alarmed at the discovery of 70% nitrgoen in all the offices in the building…
It’s true, Nitrogen is almost as dangerous as Dihydrogen Monoxide. Everyone who inhales Nitrogen dies (eventually).
As for taking 45 minutes to let people back inside, yeah, probably overreaction. And it’s not clear what the setpoint of the low oxygen content alarm was. But walking into a room (especially with a door) full of nitrogen is pretty high up there on the list of ways to die with absolutely no warning signs, isn’t it?
I’d imagine the room with the low oxygen sensor was dangerous. Here’s a recent extreme case: Couple dies inside large helium ballon.
The last sentence made me laugh out loud. Thank you.
I’ve been pushing for people to say, “It doesn’t take a molecular geneticists to realize that….”
I used to work in a cryorepository – meaning lots of big freezers filled with liquid nitrogen. So on one refill day for the big huge tank outside, the guy driving the LN2 truck was a little dumb, and started refilling the tank way overpressure for what our system could handle. So a valve burst in the supply pipes leading to the freezer, and the same thing happened. Big clouds of vapor and lots of loud alarms.
Our lab safety people were definitely very Draconian – the head of lab safety had said to us “If I ever see you re-enter the lab after a low oxygen condition, even to save somebody that’s passed out, I will make sure that you are fired.” So yeah, we weren’t allowed back in for hours after the oxygen had hit 20% again – but to be fair, it was a basement lab with no windows, so there was a fairly good chance of suffocating. The vapor was pretty cool though; it took less than five seconds after the *bang* from the valve bursting to the entire freezer room (about 15×45 feet) being filled with vapor 5 feet deep.
just wondering a bit about how these o2 sensors work, could they ice up under these conditions and give false readings?
“Sadly, they weren’t interested in the opinions of actual rocket scientists.”
Were there any around?
When you are dealing with people who have responsibility for your safety and take that responsibility seriously, stay out of their way.
None of you is fit to occupy a managerial position. The obvious solution is to ban liquid nitrogen refrigerant and specify liquid oxygen: The same temp close enough, no suffocation hazard, and a nice blue color so you can see liquid levels and spills and Tiger Teams can confirm compliance.
Think of the money to be saved on containment modalities – none are necessary! Jacket anything with a strong magnetic layer and liquid oxygen will stick to it.
Out with Fermat’s Last Theorem, too,
3472073^7 + 4627011^7 = 4710868^7
5.14880622379082621171×10^46 either way
Inconveniences of empirical fact cannot be allowed to thwart political necessities. Let’s be clever with Intelligent Design.
This story hits home for me– the building that I worked in over college had a lot of rather sensitive sensors. The oil recovery peole were always setting something off, sometimes on purpose. 🙂
I’ve got an even better one for you. One time over at Goddard Space Flight Center, the cryo folks were delivering dewars of LN2, and managed to tip one over in a parking lot. It vents, everyone stands clear, they put on gloves and pick up the frosty dewar….and the next day, the head of the hazmat team writes them up for not calling them to clean up the spill.
hi>
its fine…
i am interested in aeronoticals…
thanks for giving the messagre
What I’m wondering is, what does the floor look like after it’s been cooled with liquid nitrogen? Does it need to be replaced or does the nitrogen turn into vapor fast enough not to damage it?