"Nitrogen Blanket" stenciled on a tank car with no placard. (no Carl, I wasn't fast enough to get the mark)
The question is:
She who has no signature! cinscocom-tmw
Mook the shipper puts a Nitorgen blanket to keep that tanker when laoded from doing one of 2 things either GOING BOOM or to keep the product from oxidizing. There are certain chemicals that if exposed to air will heat up and when they get to a certain temp like to expolde. I hauled quite a few loads of them when driving OTR pay pretty well also. Also by putting a Nitrogen Blanket on then you can cut the surge down in a tanker also with a slight amount of pressure on it. Worst ones to haul with a Blanket of N2 on them are certain gasses only the DOD uses and there are a few others.
I've seen many cars labeled as having the "Nitrogen Blanket". The only thing I can assume is that they put a few (thousand) squirts of pure nitrogen in the car to prevent some sort of reaction between the commodity being transported and oxygen in the atmosphere. And what commodity might that be? Vegetable oil! At least that's what the cars I've seen are designed to haul.
No need for placards to warn against these blankets, you have the yellow warning letters. Nitrogen is the gas that makes up about 80 percent of our atmosphere, so it's not toxic, or flammable, or anything like that. However, I suspect that anyone near the car's manway when it's being unloaded would run the risk of suffocating if he breathed in a portion of that blanket (which would float out of the car because it's slightly lighter than air).
Carl
Railroader Emeritus (practiced railroading for 46 years--and in 2010 I finally got it right!)
CAACSCOCOM--I don't want to behave improperly, so I just won't behave at all. (SM)
Semper Vaporo
Pkgs.
After reading all that - Wow!
Carl, why would veggie oil need the blanket? Seems pretty harmless to me. Have anything to do with keeping it still so it doesn't "slop" around?
A Google search suggests that a layer of something inert like nitrogen (I didn't know that nitrogen was inert!) would keep vegetable oil from air-caused degradation or putrification, which is apparently exacerbated when the oil is heated or shaken. Heating shouldn't be a problem with these cars, and shaking (or, to use our technical term, sloshing) should be less of a problem the fuller a car is filled. Often the structure of the car, with the tank taking on a curved hotdog shape (another technical term), lower at the center, would cause some areas at the ends of the tank to be unable to be filled. A blanket of nitrogen might compress as it's confined to these spaces, and further reduce the sloshing, rendering it suitable for catshead biscuits served with sorghum syrup (which my sister would pronounce "Thurp").
(Retarders are wonderful things--one can, if one does it just right, cause some loaded tank cars to stop and change direction, rolling uphill for a time! Or roll down a little way, stop, start again, stop again, etc.)
CShaveRR wrote:A Google search suggests that a layer of something inert like nitrogen (I didn't know that nitrogen was inert!) would keep vegetable oil from air-caused degradation or putrification, which is apparently exacerbated when the oil is heated or shaken.
A Google search suggests that a layer of something inert like nitrogen (I didn't know that nitrogen was inert!) would keep vegetable oil from air-caused degradation or putrification, which is apparently exacerbated when the oil is heated or shaken.
Nitrogen isn't totally inert as it will react if under a high enough pressure and temperature (as in NOx from combustion). It is inert enough for the prevention of oxidation and it is much cheaper than the true inert gases (Helium, Neon, Argon, Krypton, Xenon and Radon).
I thought this would pretty straight forward and simple. Now it opens up more questions.
The commodity is vegetable oil. The nitrogen is put in the tank with the oil? (I assume right after the oil is put in the tank and it sits on top of it - hence the "blanket")?
It keeps the oil from going rancid which makes me wonder how long it is going to sit in a tanker car? OR - is it treated at the plant where it is bottled so it doesn't go rancid too fast when the consumer buys it?
What are other products that would use this "nitrogen blanket"?
And is this something that is still done today? This is the first one of those cars I have seen, so can't help but wonder if they still have the practice?
??
erikem wrote: CShaveRR wrote:A Google search suggests that a layer of something inert like nitrogen (I didn't know that nitrogen was inert!) would keep vegetable oil from air-caused degradation or putrification, which is apparently exacerbated when the oil is heated or shaken. Nitrogen isn't totally inert as it will react if under a high enough pressure and temperature (as in NOx from combustion). It is inert enough for the prevention of oxidation and it is much cheaper than the true inert gases (Helium, Neon, Argon, Krypton, Xenon and Radon).
A little bit more about Nitrogen. It's good around food-stuffs just as CTMcC said. But in some forms it's very reactive!
The fuel-oil and fertilizer bombs (that have hurt so many people) have Nitrogen-based chemistry. As pure gaseous N2, it's everywhere. but Nitrogen has a lively life - laughing gas is nitrous oxide. And so on.
John
Open questions can be fun!
Oil loaded, and then the nitrogen is added under pressure, a few pounds per square inch.
As long as outside air is kept away from the oil, it can sit in the car as long as needed...your jug of vegetable oil in your pantry last how long?
As long as air is kept away it can last several months to a year, although it rarely sits in the tank car for more than a month.
Most cooking oils are pasteurized and "cleaned" at the bottling plant.
Any produce that doest react to nitrogen and which you wish to keep sealed from air.
We get tallow cars, (lard, rendered animal fat for human consumption) here all the time, and molasses cars, all with a nitrogen blanket, it is industry standard practice.
23 17 46 11
Re. Nitrogen and foodstuffs:
That jug of Canola oil you cart home from the store has been topped off with nitrogen to enhance its shelf life. Ditto those, 'blown up like a balloon,' bags of pretzels, chips and pork rinds. Since the quantity is miniscule and pure nitrogen is non-reactive at room temperature, even the State of California exempts it from their ubiquitous dangerous product labels...
Chuck
This has been very informative. I learned a lot!
Thank you!
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