Re: Penn Salt tank cars (TRIX) comments & questions

Tony Thompson

Effective Jan 1918 Class V cars are specified and they had to be of welded construction with jackets. All valves were and are on the top. The domes are very small because the volume for the thermal expansion of the product is in the tank shell.

   Cars like this, containing pressurized gas cargoes, do NOT have an expansion dome. Thermal expansion is expressed by a rise in pressure, not by actual expansion of the cargo. The gas is pumped in and pumped out through valves in the bonnet. (There is no bottom outlet.) It really should not be called a "dome" because it does not serve the purpose of an expansion dome. It only contains valves and fittings for cargo handling. In Ed Kaminski's book on AC&F tank cars, there are several photos in the final chapter of the interior of these bonnets.

Tony Thompson             Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705
(510) 540-6538; fax, (510) 540-1937; e-mail, tony@...
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