Hey, there! Log in / Register
Nitrogen leak causes problems in Longwood Medical Area
By adamg on Mon, 09/22/2014 - 9:03am
Longwood Avenue this morning. Photo by Kellylate.
UPDATE, 9:22 a.m.: Technicians, who had to be freed from a traffic jam on Melnea Cass Boulevard, stopped the leak.
Fire crews are on Longwood Avenue this morning awaiting the arrival of a crew that can shut off a nitrogen leak. Stanley Staco reports Harvard evacuated three buildings due to the leak.
Parents of students at Boston Latin School got robocalls this morning that while the leak poses no threat to students, the school had gone into "safe mode," in which students were not being allowed outside.
The offending tank (photo by BFD):
Neighborhoods:
Free tagging:
Ad:
Support Universal Hub
Help keep Universal Hub going. If you like what we're up to and want to help out, please consider a (completely non-deductible) contribution.
Comments
More info
From an area alert email:
There is a nitrogen leak at the Harvard School of Public Health from an external tank behind 180 Longwood Avenue, and Harvard buildings, including HSPH, are are being evacuated as a precaution.
What are they teaching at Boston Latin?
They're keeping them inside?!? But the nitrogen levels inside the school are already hovering around 78%! Those kids might suffocate in there!
Nitrogen wouldn't be their problem
Getting run over by emergency responders is a real risk.
Accurate description of the danger
The danger of a leaking liquid nitrogen tank is not the nitrogen (ok, Little Dutch Boy, don't go trying to stick your finger in the leak or anything to prove me wrong). The atmosphere is just under 80% nitrogen. The meaningless amount trapped in the tank isn't going to suddenly suffocate you in the great out of doors in the way lots of other gasses might if they are denser than nitrogen and will push out all the natural air and oxygen. It'd take a confined space where the 100% nitrogen from the tank was replacing the air so there was no oxygen left.
The much more real risk is failure of the containing vessel, a tank rupture. At that point, depending on the size and type of the nitrogen tank, you could be talking about probably a few thousands of Newtons of force. Here's a great description of a medium sized nitrogen tank that was stupidly "fixed" in a way that caused it to explode: http://pipeline.corante.com/archives/2006/03/08/how_not_to_do_it_liquid_...
It's an impressive description of damage.
They Should Have Known Better, But It Was Texas, So They Didn't
The nitrogen was being released because the relief valve opened
You know, that thing that's there to prevent a dangerous pressure build-up? Either it opened because there was a dangerous pressure build-up - which it has relieved - or it failed in an open state, which would also prevent any possible dangerous tank failure.
If it is a liquid Nitrogen leak - which is not stated in the news reports - the danger would be from coming in prolonged contact with the cryogenic liquid. You'd almost have to consciously try to do that.
Another Danger
If you were in a space where the nitrogen was able to displace the air containing oxygen.
Given that it is an external tank, this isn't a very likely possibility.
Yep, low danger
Yes, I posted that because it's the biggest risk before it was determined to be a stuck open pressure valve. There's low danger over a stuck open valve, just a lot of wasted money/nitrogen. Hopefully whatever it was feeding has a back-up source of cooling power or if it was feeding the house nitrogen lines for chemistry purposes, then I hope nothing was in the process of relying on it or someone's chemistry experiment isn't going to have worked the way they thought today.
Either way, it's unlikely anything catastrophic will happen with a stuck open valve. However, whatever caused it to fail might need investigation to determine if pressure build-up didn't cause it to fail open because something else had gone wrong in the containment system first.
But that isn't the case
That's an opposite problem. A sealed cryo tank is prone to blowout. A leaking one is not.
My experience is that once the fire department gets called in to any problem in a lab environment, they always shut everything down.
Depends on the leak
Yes, the example described is what happens when the liquid nitrogen in a fully sealed (unable to pressure vent) vessel reaches its failure pressure. This is similar to what Mythbusters do with home hot water heaters on a number of their episodes.
A leaking tank could be due to failure at the valves as you say OR a limited failure of the outer tank wall. A pierced tank does not automatically rupture and explode...but is VERY susceptible to doing so once the tank's structure is violated. The tanks have two shells with a vacuum between them to insulate the temperature difference and reduce the boiling and loss of the super-cold liquid inside.
If the outer tank fails, the warm air that replaces the vacuum can cause problems on the inner tank which can lead to a leak of liquid nitrogen into the outer tank. The temperature of leaking gas causes the tank to lose its integrity and become extremely brittle. The outer temperature also causes the nitrogen to boil into a gas from its stored liquid form as it leaks into the space between the two tank walls. Essentially it becomes a giant grenade waiting for total tank failure (usually along a welding in the outer tank) unless the leaking gas can escape fast enough without over-pressurizing the outer tank first.
This one sounds like someone noticed either an extended release of pressure from a safety valve and reported it or a stuck-open valve that was wasting the nitrogen. Either way, I hope someone's frozen samples are still doing okay.
It's liquid N2 , looks like
It's liquid N2 , looks like it is the liquid that is leaking ,as opposed to the gas venting out a safety due to pressure build up. Don't let the liquid hit you, even in a mist , without protection. It's inert, only hurt you if it displaces the oxygen in the air you breath. Just let it vent off.l looks like a 2500 or 3000 gal.tank , belonging to Airgas, probably sourced out of Bozrah Ct. ASU.
Nitrogen is our friend !
The picture wasn't there earlier
Which is why I said none of the news reports said it was LN2. As you say, it's really not very hazardous if you keep a little distance. That thing with the Liquid Metal guy in Terminator 2? Utter nonsense.
There are no large storage
There are no large storage tanks for gaseous N2 . Big amounts are delivered by tube trailer in the gaseous state, smaller amounts in portable banks, which are just a bunch of cylinders on a dolly manifolded together to one out fitting. You wouldn't see these leaking , just hear it.
Now , if in this case , the product was liquid O2 or worse , liquid hydrogen, it would have required a more careful response. They might have had to cut electric power off in the area.
Bonus learning video : A Day in the Life of an Air Products
https://m.youtube.com/watch?v=ox1F8HacZyk
Nitrogen? Who cares! There are terrorists on the loose!
Didn't you read today's Herald? Hide! Hide everyone from the Muslim scourge that's surely the advance team for an ISIS invasion! Benghazi!!
Nah
The missing guys must have gotten married in Provincetown, because they headed for a honeymoon in Niagara Falls.