Tank car placement Qs

I read in Vol. 1 of the Kalmach book on industries that tank cars carrying flammable material weren’t right behind the locos. Here are my questions:

1 Was keeping these cars away from the locos required by law or just general practice?

2 What types of material was considered “flammable?”

3 Is it true that that box cars were used to separate the flammable cars from the locos?

TIA!

Lee

Depending on era, required by Federal law. Loaded placarded cars “generally” are required to be 6 cars from an engine or occupied car, empty placarded cars have to be the 2nd car from an engine or occupied car.

There are all sorts of commodities that are restricted.

Flammable Solids

Flammable liquids

Flammable gases

Oxidizers

Poison

Poison gas

Non-flammable gas

Corrosives

Explosives

Any non-placarded car or a cars with combustible placards can be used for cover (boxcars, flatcars, hoppers, covered hoppers, tank cars, etc.)

Dave H.