Re: Tichy tank car

Dave Parker

On Wed, Aug 14, 2019 at 12:36 PM, Tony Thompson wrote:
 BTW, in response to Scott Chatfield's comment about dome volume, it was required to be a MINIMUM of 2 percent of the tank volume. Car buyers could choose to have larger domes if they wished.
Just to clarify, the 2% requirement dates only to the creation of, and mandatory construction to, the Class III  and IV standards of May, 1917.  Many, perhaps the majority, of Class II cars had domes noticeably smaller than this minimum percentage, and many were used in interchange for decades thereafter.

And indeed some car buyers (Texcao most notably) insisted on larger, sometimes much larger, domes.  The reason was that depending on the commodity, and the loading temperature, 2% was an insufficient expansion volume, and extra headspace had to be provided by not filling the tank to 100% of capacity.  Each car design had an outage table to allow shippers to "conveniently"  determine the correct fill level.  Texaco obviously preferred to simplify things, which is why their ACF Type 21 10 kgal cars had 420-gal domes (versus the "standard" ACF build of 210 gallons).

Dave Parker  
Riverside, CA

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