Volume/Mass of Rail Cars for hydrocarbons

Good day;

I am investigating a measurement issue at a facility and I wonder if you folks would be able to help me as I am completely ignorant regarding rail transport!

I am looking at a volume coming into the facility that repeats in multiples of 170.23 BBL or 27 M3 multiple times. (7150 gallons). The product is light hydrocarbon - possibly Butane/Pentane or similar. The location is in LA north of Shreveport.

Does this volume make sense if it came from a rail car? From what I can see online most tankers DOT-111 are much larger, but it may be a weight restriction or multiple compartments on the rail car? The product density would make the mass of the product 16 to 21 metric tons (42,000 lbs to 56,000 lbs).

Basically what I really need to know - does this increment represent a whole product load of a rail car, a compartment of the rail car (if that exists?) or does it have no relation?
I really appreciate any response/information

Thank you.

Mr Craft: Propane and similar light hydrocarbons are required to be moved in so-called "pressure"cars in the 33-34,000+ gal capacity range. Tank car sizes are optimized for product categories to balance capacity against maximum gross weight limitations (increasingly 286,000 lbs). In short, the less dense the product, the larger the car... and propane cars are as big as they get. Smaller cars don't make sense as you're paying the railroad to haul around a bunch of steel and very little product.

Thank you for the response. I really appreciate the information and that does make a lot of sense!