Why short tank cars?

The density of the commodity and its compatibility with the tankcar material and construction are probably the main reasons for choosing what type of tankcar to use. You don't want to partially load a large tankcar with a dense commodity because it will really slosh around and possibly derail the car. Most gases are shipped liquefied, so this applies to liquids and (usually) to gases.

ericsp

The density of the commodity and its compatibility with the tankcar material and construction

  Why didn't I think of that!?!

Then again... I'd have thought that tar would be pretty dense and that travels in larger cars... so maybe there are issues about viscosity as well?

Thanks

I looked at some MSDS to get some specific gravities. Here they are with typical tankcar sizes.

Molten sulfur: SG=2.06; 16,000 gallon tankcars
Hydrochloric acid: SG=1.16; 20,000 gallon tanckars
Asphalt: 0.95<=SG<=1.13; 23,500 gallon tankcars
Gasoline: 0.70<=SG<=0.77; see below
Natural gasoline: 0.5<=SG<=0.7; see below

I have seen tankcars ranging from 30,000 to 33,900 gallons placarded for gasoline, which can include natural gasoline. 

Thanks

  Being from the east side of the pond I don't have a clue what MSDS is???

What would be the l;engths of those cars please?  (Partly I'm lost on US Gallons... I was Imperial (long) gallons but then they metricated me ).

Thanks

MSDS = Material Safety Data Sheet

16,000 gallon tankcars are usually around 40 to 45 feet long. 

20,000 gallon tankcars are usually around 50 feet long.

23,500 gallon tankcars are usually around 55 feet long. 

30,000 gallon tankcars are range from about 70 feet long to around 60 feet long. The trend lately is large diameter, shorter tanks.

The 33,900 gallon tankcars are the big LPG tankcars, they range in length from 63 feet to 71 feet. 

Great Thanks

Of course that leaves me wondering what would go in a 30' car that's worse than hydrochloric acid...  Possibly Nitric amongst others...

Where would I find info on the correct hazard diamonds please?

Thanks

They are for heavy commodities, not small amounts.  Just like ore cars are shorter than a woodchip car because ore is denser than wood chips, a lead tetraethyl car that can carry 70 tons will be shorter than a gasoline tank car that carries 70 tons.

 Water weighs 62 lb/cu ft and lead tetra ethyl weighs 101 lb/cu ft.  A 70 ton water car would need 2300 cu ft ov volume while a 70 ton lead tetra ethyl car would only need 1400 cu ft, almost one half the size of the water car.  If you loaded a 2300 cu ft capy water car with lead tetra ethyl it would weigh 116.5 tons, waaaaay overloaded.

So the premise that they are for small shipments can be wrong.

 Short and fat is that they build a standard diameter tank and then adjust the length to suit the density of the commodity/commodities the car is designed to carry.

Liquid sulphur is another heavy commodity and it travels in unit tank movements ranging from a few cars to unit trains.

My darkness is being lightened!  Thanks

dehusman

lead tetra ethyl

Diamonds?  Red is flamable IIRC but what are the other colours please?

Walthers, among others, do several different sulphur cars, about 40' cars IIRC.  I've often wondered what so much sulphur would get used for?  (Building volcanoes)?

Thanks

Its the lead in leaded gasoline.  Flammable liquid.  Commonly seen in little tiny green and yellow Dupont tank cars.

Do a hazardous placard image search on Google for pictures of the placards, Microscale sold a decal sheet of placards I think.

If you search for the "hazard class" of a commodity that ought to tell you what placard it needs.

You might recall the article and scale drawings some years ago in Model Railroader (Feb 2001?) concerning some special tank cars built to haul a particular sort of slurry bromine that was found if memory serves underground near Detroit.  The stuff was so dense that even a very small tank was in fact very heavy.  It looked like putting an HO tank on an S or O scale frame.  When the supply was exhausted (or the demand disappeared; I cannot recall which) the cars were essentially worthless because they were absurdly small for any other commodity so were scrapped.

I don't know about tanks cars but one reason why reefers were kept at 36 ft long after other house cars became standardized at 40 ft was the the loading docks and icing platforms were all set up for 36 ft cars.  The thought strikes me that some customers for tanks cars might have dictated a certain length so that a string of cars could use existing facilities, even if a longer car could have hauled the same material. 

Dave Nelson

 bromine is a very heavy liquid in it's pure state.  the tanks were lined with lead.

grizlump

As has been documented above, the density of the product generally dictates car size. Naturally, a denser product will consume much less volume than a lighter, less dense material. It all has to do with how much you can put into a tank before it reaches either 263 or 286K GRL (depends on what you're shipping).  Some commodities, the less dangerous ones like corn syrup or clay slurry, are permitted to 286 GRL, but pretty much anything that can burn or explode is limited to 263 GRL.

Another factor is customer loading racks; some large shippers have very elaborate loading racks tailored to a specific car length and top platform arrangement. In the past, it has been the case where a new length or diameter car comes out, and the shipper (when the cars come off lease) will elect to retain the older cars because tehy fit the loading rack. Thus, a shipped may elect to have a shorter, larger diameter car so that more cars can be fitted in a given loading space. For example, the first 30,000 gal cars that came out were quite long, as they used a tank diameter that was more common at the time, but the 30's that were built in the last few years are much shorter (about 9 feet) and have a bigger diameter. Hence, the older 30's are sometimes harder to find a home for.

Also, gasoline (like you would put in your car) is shipped in 30,000 gal cars. Ethanol and various other products are too, and so is diesel, but it is shortloaded; the ideal diesel car is about 27,000 gal, as it is slightly heavier. Natural gas liquids (aka diluent or condensate) is used a lot these days in the Alberat oil sands, as the crude is too thick to flow or handle easily, and is thinned out by the diluent. The key different is that is travels in a pressure car (33,900 gal) but gasoline travels in non-pressure, DOT 111A tanks.

Chlorine is an exception. It is government limited to 90 tons/car, and travels in a 500lb pressure car (again, this is mandated; chlorine actually generates nowhere near this much vapour pressure - it is a safety measure). All chlorine cars have the same load limit, except a few older cars built to 45 ton limits.

 And one final thing to keep in mind, the outside diameter of the car is not necessarily the outside diameter of the tank - many tankcars have insulation (i.e. corn syrup, some grades of supfuric acid, etc..)

Hope you find this helpful. Cheers,

Peter.

From my observations of cars that come through my area and looking at the quantity of photographs of tankcars less than 40 feet long on websites, they appear to be very rear. The link below has photographs of such cars, although some appear to be longer.
http://www.rrpicturearchives.net/rsPicture.aspx?&aid=T103&NumCols=2&Page=1

I have seen such tankcars owned by Dow that carried sytrene-butadiene latex, pentachloropyridine, and tetrachloropyridine. The Dow SB Iatexes I looked up have a specific gravity of 1.08, so suspect that reason for it being shipped in such small tankcars is the quantity used. I have not been able to find densities or specific gravities for the pyridines. However, I have also seen tetrachloropyridine shipped in larger tankcars.

I have also seen tankcars less than 40 feet long leased to Lubrizol and others owned by Chevron Oronite go to the Chevron refinery in Richmond, CA. They must be carrying some type of additive. The Lubrizol tankcars were placarded for flammable liquid, not otherwise specified. The Oronite tankcars are not placarded. I do not know what they carry and I am not going to try to find the densities or specific gravities of all of their products, so I do not know the reason they use such small cars.

This thread contains links to information about haz-mat placards. Also, go to the Department of Transportation's website and search for the Emergency Response Guidebook. 

Fantastic responses   Thankyou everyone.

I have pictures of some (large) tank cars that haven't had their cladding fitted.  I will try to get them posted.

Thanks

Dave-the-Train

My darkness is being lightened!  Thanks

dehusman

lead tetra ethyl

  What on earth is that?  What's it used for?

Diamonds?  Red is flamable IIRC but what are the other colours please?

Walthers, among others, do several different sulphur cars, about 40' cars IIRC.  I've often wondered what so much sulphur would get used for?  (Building volcanoes)?

Thanks

One of the main uses of sulfur is in manufacturing fertilizers. It is also used in its almost pure form as a fungicide.

I think most man made volcanoes are made using baking soda and vinegar.

ericsp

I think most man made volcanoes are made using baking soda and vinegar

Not the chemistry undergraduate twins I knew... Don't know what they used as young teens but the local cops figured out how a brick got right over the opposite house by the hole left in their parents drive... Last seen they graduated and got recruited by the Ministry of Defence...

As they say on TV "Don't try this at home".

Here is a photograph of a bromine tankcar.
http://www.rrpicturearchives.net/showPicture.aspx?id=815502

 Does any one know what EBEX stands for. If I do a search all I get is, Do you mean EBAY?

Do you mean EBAX? If so, it is the reporting marks for Albermarle Corporation. 

ericsp

Here is a photograph of a bromine tankcar.
http://www.rrpicturearchives.net/showPicture.aspx?id=815502

That's quite a car!    Anyone fancy doing the lettering on it? 

Lake - you can find loads more on reporting marks in Wikipedia http://en.wikipedia.org/wiki/Reporting_marks

 ericsp,

I did mean to type EBAX. It was late. Thanks for the reporting mark name.