At one of my favorite train watch spots yesterday, a train with a lot of tank cars went by. Some of the cars appeared to be approximately 40 feet long, but others were much longer. Maybe 75 to 80 feet!
What accounts for the difference in the car lengths? Do the smaller cars, for example, tend to carry a different product than the larger cars? Or is this just one of those it is what it is things?
Rio Grande Valley, CFI,CFII
AAR FIELD GUIDE TO TANK CARS
https://www.aar.org/Documents/BOE/2017%20Field%20Guide%20for%20Tank%20Cars.pdf
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As I understand it tank cars are designed to carry specific chemicals some of which are heavier than others but none of which can exceed the 286,000 pound limit on the rails. Heavier liquids demand shorter cars so they don't exceed the axle load limits. Longer cars carry lighter liquids.
Norm
could it be that some product's receivers do not need a big tank car of product at one time ? As well it may be some products have a short shelf life or half life ? Contamination if kept too long is another consideration ? H2O2 will certainly soak up water.
Major league transportation is based on cube and weight - no matter the vehicle. Heavy commodities reach the weight limits with smaller vehicles. Light commodities may not reach the weight limits even with the largest available vehicle.
Shippers don't want to pay to ship air.
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I think it's tetraethyl lead, or something like that, has a really short tank car, due to the weight of the product.
It may be easier to consider certain dry cargos, like comparing iron ore/pellets with grains.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
blue streak 1 could it be that some product's receivers do not need a big tank car of product at one time ? As well it may be some products have a short shelf life or half life ? Contamination if kept too long is another consideration ? H2O2 will certainly soak up water.
Hydrogen peroxide does not "soak up" water. It loses an Oxygen atom and BECOMES water
Larry, what use is there for tetraethyl lead nowadays since it is no longer put into gasoline?
Johnny
DeggestyLarry, what use is there for tetraethyl lead nowadays since it is no longer put into gasoline?
It is still used in off road fuel. I'm paying $10 a gallon for 112 octane racing fuel with lead.
BaltACD Deggesty Larry, what use is there for tetraethyl lead nowadays since it is no longer put into gasoline? It is still used in off road fuel. I'm paying $10 a gallon for 112 octane racing fuel with lead.
Deggesty Larry, what use is there for tetraethyl lead nowadays since it is no longer put into gasoline?
It's also used in aviation gasolene, though currently available avgas has nowhere near the lead content of the "weapons grade" 115/145 avgas.
I'm not even sure it was tetraethyl lead, but whatever the liquid in that tank car was, it was much heavier than plain ol' water.
JPS1 At one of my favorite train watch spots yesterday, a train with a lot of tank cars went by. Some of the cars appeared to be approximately 40 feet long, but others were much longer. Maybe 75 to 80 feet! What accounts for the difference in the car lengths? Do the smaller cars, for example, tend to carry a different product than the larger cars? Or is this just one of those it is what it is things?
Sam,
Two words "bulk density", that is the weight per gallon or specific gravity which can be used to calculate weight per gallon or the product the car was designed to carry.
Before I elaborate you should know that I worked for the Bureau of Explosives for 5 years and Southern Pacific Hazardous Material Control for 8, so I lived and breathed tank cars for 13 years. The balance of this is based on 263,000 pound gross weight on rails which was the regulatory limit when I was working in the 1970s and 1980s. That limit was imposed after 6 axle and 8 axle cars got in trouble, but that is a separate story and before my time in the business.
That 263,000 pounds is utilized in one of two ways, tare weight and weight of product, or lading. A 263,000# car is said to be a "nominal 100 ton" car. Consider a grain car sized for wheat. It will have a tare weight of 60,000 - 63,000 pounds leaving a lading weight of 100 tons. At 60#/bu that is 3,333 bushels. Convert bu. to cubic feet, and add a bit for space not filled due to the slope of grain in the car, and you will find a lot of 4425 cuft grain cars in the system. If you want to also carry barley, which is a bit lighter you go to 4700 cubic feet, but wheat loaders have to be careful not to overload these cars.
Now lets consider two products at opposite ends of the density line, Liquefied Petroleum Gas (LPG) and Sulfuric Acid. Before we go any farther we must state the obvious, tank cars are built to carry one product or a specific range of products. Also the speculation about part loads elsewhere in this topic is pure bunk. When I started in 1974 there were still a few compartmented tanks in service, but they are long gone. There were also nominal 50 and 70 ton cars in service so a customer could order those smaller lot sizes. Again long gone.
As you probably know, LPG refers to both propane and butane, and LPG cars are also used to transport Anhydous Ammonia. For simplicity lets assume Propane, which is light enough that with an 80,000# tare car, tank capacity was usually 33,000 gallons in a 112A340W car. The tare is more than our grain car because the tank itself it thicker than the floor, walls, and roof of the grain car, and the tank is longer.
The shipper wants to get as much weight into the car as he can, in this case 183,000 pounds. He is working against two limits, the carrying capacity limit of 183,000# AND the volume limit of 33,000 gallons less "outage". Outage is vacant space left in the car to assure that if the load heats up during transit, the tank will not become litterally shell full. If that happens, then liquid propane will be discharged from the safety valve, a bad thing. In the case of propane the guy who loads the car goes through a page of calculations to determine where to set his slip tube. Loading is supposed to be halted when liqiud propane is first discharged from the slip tube.
Sulfuric Acid weighs about 13 pounds per gallon. A modern Class 111 car with a 65,000# tare the car will carry 198,000 pounds of product. That is 15,200 gallons of product. I clearly recall these cars being 13,300 gross gallons, so either my tare weight or density recollection, or both, are a bit off. With acid, the outage had to be at least 1% or 133 gallons, for a net load of 13,167 gallons. Quantiy was measured by an in-line counter similar in concept to that on a gasoline pump at a gas station.
Many Flammabe Liquids are lighter than water, and cars generally ran in the 22-25,000 gallon range. Flammable Liquids requre 2% outage. All Class 111 Flammable Liquid cars have a fixed indicator in the manway the bottom of which is set at the 2% outage level. Loaders can load to the bottom of the indicator unless the product is so dense as to require more outage due to weight.
In addition, insulation tends to make the car look a bit larger than it really is. In comparison with bulk density variationsthis is a minor issue.
Finally, though you did not ask I will mention, that the older nonpressure cars, Class 103 had expansion domes of 1% for acid and 2% for flammable liquids. Here the loader could load the tank shell full and the dome would accomodate any in transit expansion.
Mac McCulloch
erikemIt's also used in aviation gasolene, though currently available avgas has nowhere near the lead content of the "weapons grade" 115/145 avgas.
Erik,
I don't think "Purple Gas" has been seen since the heavy military bombers such as the B-36 last flew. There is still lead in avgas (No, I don't mean Jet A or B) but 100LL is still very common for the recips of todays GA aircraft. Even "Green Gas" has not been available for quite some time.
PNWRMNM,
Thanks for your thoughtful explanation of tank car differences.
If the car is designed to carry a corrosive product, would it be lined with a material that would prevent the inside of the car from being eaten away?
Norm48327 erikem It's also used in aviation gasolene, though currently available avgas has nowhere near the lead content of the "weapons grade" 115/145 avgas. Erik, I don't think "Purple Gas" has been seen since the heavy military bombers such as the B-36 last flew. There is still lead in avgas (No, I don't mean Jet A or B) but 100LL is still very common for the recips of todays GA aircraft. Even "Green Gas" has not been available for quite some time.
erikem It's also used in aviation gasolene, though currently available avgas has nowhere near the lead content of the "weapons grade" 115/145 avgas.
I have seen various octane rated Sunoco race fuels with different dyes added so they can be differentiated. I have seen Blue, Purple, Green and Pink.
JPS1 PNWRMNM, Thanks for your thoughtful explanation of tank car differences. If the car is designed to carry a corrosive product, would it be lined with a material that would prevent the inside of the car from being eaten away?
As a general matter yes, but not always. It depends on the nature of the product. The car builders are expert at this, but I did not have to be in the positions I occupied.
Hydrochloric Acid has its own Specification, DOT111A100W5, which by the definition of the spec included rubber lining.
Cars are often lined to protect the purity of the product as well.
Mac
Based on various articles on the big recips, "purple gas" seems to have been available until the early 1970's. There were still a number of plans flying with Wasp Major's and Turbo Compounds that could use purple gas for a bit extra manifold pressure.
erikem The last C-124 was retired in Sept 1974. They had 4 R4360 engines. their are still aircraft flying which originaly called for 115-145 fuel ( These are "performance numbers, not octane ratings, anything above 100 would be an extapolation at best.) They are usually not pushed to perform at that level or as in the case of unlimited air racers, use custom blended fuel. Norm48327 erikem It's also used in aviation gasolene, though currently available avgas has nowhere near the lead content of the "weapons grade" 115/145 avgas. Erik, I don't think "Purple Gas" has been seen since the heavy military bombers such as the B-36 last flew. There is still lead in avgas (No, I don't mean Jet A or B) but 100LL is still very common for the recips of todays GA aircraft. Even "Green Gas" has not been available for quite some time. Based on various articles on the big recips, "purple gas" seems to have been available until the early 1970's. There were still a number of plans flying with Wasp Major's and Turbo Compounds that could use purple gas for a bit extra manifold pressure.
The last C-124 was retired in Sept 1974. They had 4 R4360 engines. their are still aircraft flying which originaly called for 115-145 fuel ( These are "performance numbers, not octane ratings, anything above 100 would be an extapolation at best.) They are usually not pushed to perform at that level or as in the case of unlimited air racers, use custom blended fuel.
Balt, thanks so much for that reference; I've now bookmarked it.JPS1, I'm betting you saw a train on a western railroad, probably Union Pacific. The short cars may have been for the transportation of corn syrup and the larger ones (closer to 60 feet long) were probably for ethanol.
Carl
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Some really heavy chemicals like bromine, travel in some really small tank cars:
http://www.rrpicturearchives.net/showPicture.aspx?id=815502
MidlandMike Some really heavy chemicals like bromine, travel in some really small tank cars: http://www.rrpicturearchives.net/showPicture.aspx?id=815502
Yes, bromine is very heavy, but the load limit of the car is only 60,000 pounds as best as I can read it. Weight of load is roughly 1/3 of that of a nominal 100 ton car.
PNWRMNM MidlandMike Some really heavy chemicals like bromine, travel in some really small tank cars: http://www.rrpicturearchives.net/showPicture.aspx?id=815502 Yes, bromine is very heavy, but the load limit of the car is only 60,000 pounds as best as I can read it. Weight of load is roughly 1/3 of that of a nominal 100 ton car. Mac
Car is still listed in UMLER, however it is not legal in Interchange Service. Outside length of the car is 29 feet 2 inches. Its allowed maximum weight on rail is 108K pounds.
CShaveRR Balt, thanks so much for that reference; I've now bookmarked it.JPS1, I'm betting you saw a train on a western railroad, probably Union Pacific. The short cars may have been for the transportation of corn syrup and the larger ones (closer to 60 feet long) were probably for ethanol.
Yep! On the UP near Marfa, TX. I have no sense of size and measurement. Closer to 60 feet sounds good to me.
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