Western Railroad Discussion > Why are tank cars black, not white?

Black absorbs heat, white reflects heat. A cool load of, say, ethanol should be safer than a hot load. Therefore tank cars should be painted white. In fact tank cars are usually black. Does anyone know why?

I have several black tanks and several white tanks, with others that are gray, blue, rust brown, etc. So they are out there.

Bob

atsfman Wrote:
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> I have several black tanks and several white
> tanks, with others that are gray, blue, rust
> brown, etc. So they are out there.

True, but most tank cars are indeed black. An empty unit ethanol train I photographed yesterday had 70 tank cars; one was a brownish red, one was white, and the other 68 were black.

I'm not sure, though, that the exterior color of the car physically affects the load too much. What you see on a tank car is often an exterior jacket, with the actual tank contained inside, so heat from the sun may not necessarily be transmitted to the lading.

At one time wasn't there a color code for tank cars put out by the FRA to symbolize the type of contents (flamable etc)?

Maybe it was just a "guy thing".

mukinduri Wrote:
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> Black absorbs heat, white reflects heat. A cool
> load of, say, ethanol should be safer than a hot
> load. Therefore tank cars should be painted white.
> In fact tank cars are usually black. Does anyone
> know why?


Black paint is cheaper since it is composed of all the left over colors mixed together.

All that liquid can abxorb so much more heat than would be taken in from sitting the the hot sun, that it really doesn't matter. Tests revealed that a tank sitting in a fire still was able to absorb an amazing amount of heat before it became a problem. Most fires from derailments are due to tank failure.

KK

Many of the earliest tank cars carried crude oil and refined petroleum products. A black tank car would hide spills pretty well and black paint is relatively cheap to buy. Now there is a rainbow of tank car colors in the field. Yellow painted tanks make sulphur spills less noticeable. White tanks are common for commodities which are shipped cooler to keep them from getting too hot. Since tank cars are loaded with room for product expansion some heating is not too much of an issue and the volumes inside the tank will take some time to heat to a higher uniform temperature. So no need to worry about what color the cars are painted.

tomstp Wrote:
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> At one time wasn't there a color code for tank
> cars put out by the FRA to symbolize the type of
> contents (flammable etc)?

The only cars I've seen that seemed to be content-specific were the hydrocyanic acid cars that are white with a red band -- referred to as candy-stripers. But I haven't seen any of those in quite some time.

All the gray tanks I've seen have belonged to Occidental Chemical/HOKX and have carried either chlorine (pressure cars) or sodium hydroxide (not pressurized). But there are other shippers of these chemicals whose cars are white, black, or some combination of the two. Just saw some solid-white chlorine cars the other day in the "neighborhood," which was a first for me.

P{lacarded '1075' loads were in white tanks...

Kennecott ships sulfuric acid which is a byproduct of copper smelting in white tank cars.

Agt-Highland Wrote:
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> Placarded '1075' loads were in white tanks...

That would be liquefied petroleum gas (propane), which I've seen in white cars, black cars, and even a few blue cars. Decades ago, many propane shippers had billboard lettering on their cars, but that's all gone now and security-wise that's probably a good thing.

White tanks also are common for sulphuric and phosphoric acids and anhydrous ammonia, but you'll see those chemicals shipped in black tank cars quite commonly, too.

The only commodity I can think of that is predominantly shipped in white tank cars is kaolin clay slurry for the paper industry. Kaolin is what makes glossy paper glossy.

Kaolin is also used in the making of wallboard. Theres a kaolin plant in N. Rutland, VT called OMYA and they have a fleet of tankers and hoppers.

cpvo Wrote:
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> Kaolin is also used in the making of wallboard.
> Theres a kaolin plant in N. Rutland, VT called
> OMYA and they have a fleet of tankers and hoppers.

I thought that plant up there made calcium carbonate from crushed marble.

cpvo Wrote:
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> Kaolin is also used in the making of wallboard.
> Theres a kaolin plant in N. Rutland, VT called
> OMYA and they have a fleet of tankers and hoppers.

I thought that plant up there made calcium carbonate from crushed marble.

And according to wikipedia, Kaolin was also a primary ingredient in Kaopectate -- hence the name -- for many years.

toledopatch Wrote:
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> The only cars I've seen that seemed to be
> content-specific were the hydrocyanic acid cars
> that are white with a red band -- referred to as
> candy-stripers. But I haven't seen any of those in
> quite some time.

I think they are still out there - just very rare. I believe this is one of the very few examples of markings legislated by the FRA.

Another content-specific example would be ferric chloride. There are many exceptions, but much of the time ferric chloride cars are solid rust-brown color or white with a rust-brown vertical band at the center.

>
> All the gray tanks I've seen have belonged to
> Occidental Chemical/HOKX and have carried either
> chlorine (pressure cars) or sodium hydroxide (not
> pressurized).

Hmmm... Dow's 'signature color' is light gray, found on DOWX cars as well as leased ACFX, etc. cars.

BN_FAN Wrote:
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> toledopatch Wrote:
> --------------------------------------------------
> -----
> > The only cars I've seen that seemed to be
> > content-specific were the hydrocyanic acid cars
> > that are white with a red band -- referred to
> as
> > candy-stripers. But I haven't seen any of those
> in
> > quite some time.
>
> I think they are still out there - just very rare.
> I believe this is one of the very few examples of
> markings legislated by the FRA.

Those things were scary. Another Bhopal waiting to happen.

BN_FAN Wrote:
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> Hmmm... Dow's 'signature color' is light gray,
> found on DOWX cars as well as leased ACFX, etc.
> cars.

The DOWX cars I see up in Durand, MI (to/from the Midland plant) are mostly white cars -- including the latex tanks. Actually, that reminds me that all of the latex tanks I can recall seeing were white. If they're actually a shade of gray, it's a very light shade; the HOKX/Occidental cars are an unmistakable medium-to-dark gray -- darker than the gray on KCS locomotives.

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> All that liquid can abxorb so much more heat than
> would be taken in from sitting the the hot sun,
> that it really doesn't matter. Tests revealed
> that a tank sitting in a fire still was able to
> absorb an amazing amount of heat before it became
> a problem. Most fires from derailments are due to
> tank failure.


The current fire in KC might provide a good example of that. There is a black tank car right next to the flames that have been burning for about an hour. You can watch live coverage here:

http://web.kshb.com/kshb/breaking_news/index.shtml

Saw two white tank cars today being picked up by a local freight off local short line interchange. Reporting mark was UTLX with notation,leased to Dow Chemical. Hazmat placard no. 1268. They had been graffitied, reporting marks and other info was still visible.

Paul Bliss
Oxnard CA