Re: unloading a tank car through the bottom valve

Steve Lucas <stevelucas3@...>

I have a photo from the 1920's showing an Imperial Oil tank car being unloaded thorugh the bottom valve.

But using these valves can sometime be attended with problems. I was told (at a "TransCaer Safety Train" seminar on their demonstration tank car CCPX 911) of objects like pens falling into a tank after the bottom outlet cap (chained to the bottom outlet) was replaced on the outlet. Now, the bottom valve does not close fully, as that pen is stuck in it...

On arrival at the consignee, their employee places a five-gallon bucket under the outlet to catch the half-gallon or so of product that will be trapped in the cap. He unscrews the cap, to find the valve partly open, allowing the contents of the car to drain into the bucket. Uh-oh! Now imagine trying to hook up the discharge hose to the outlet with product issuing from it. And what's in the car that may block and/or damage that hose?

Flammable product spilt on the ground, a mess to clean up, and no way to stop the flow other than to replace the cap with product still flowing out of the car. Lost product = money. The mess will be expensive to clean up, too.

Which to me expalins why many consignees preferred to unload tank cars by suction/eduction pipes rather than through that bottom outlet valve.

Steve Lucas.

--- In STMFC@..., "traininsp" <Bbear746@...> wrote:

The bottom outlet valves used on steam era tank cars were 4 & 6 inch plug valves, the same design that's still in used today. On the tanks with expansion domes the valve handle (wheel) was located in the dome.
I'm sure they were used often.

Jeff Coleman

--- In STMFC@..., Anthony Thompson <thompson@> wrote:

Ed Mines wrote:
The bottom valves on steam era tank cars are way too small to allow
the car to be emptied in a timely manner.
Where do you get this idea? It was done very widely and all the
time. And photos I've seen of top unloading pipes are no larger than
the outlet pipes at the bottom.

I have a feeling they were difficult to open too; otherwise thieves,
vandals, hobos etc. would be opening them.
Nope, the accessible part is just a pipe cap on the outlet
pipe, but that's not enough to unload. You also have to open the
valve, which is INSIDE the tank and operated from the dome. See any
steam-era Cyc or a book like Ed Kaminski's _AC&F Tank Cars_ for

I think tank cars used to transport ashphalt, roofing tar etc. were
the tank car equivalent of hide loading box cars.
Not at all. Tank cars could be and were cleaned for new
cargoes. Of course it cost time and money, but it was certainly
possible. The major exceptions were cars with particular linings, such
as rubber linings for acid, which you would not want to use for
anything which could interact with the lining.

Tony Thompson Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705
(510) 540-6538; fax, (510) 540-1937; e-mail, thompson@
Publishers of books on railroad history

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