Bob Chaparro wrote:
"Refrigerator Cars - Salt Water Drippings
This text is from the 1925 Car Builders' Cyclopedia Of American Practice.
Note that from 1923 onward, brine in ice tanks was not to be allowed to drip on to the track. This was to prevent corrosion damage to track, bridges and electrical circuits. Brine was to be drained at icing stations."
Never rely on Car Builders' Cyclopedias for such dates without verification from other sources. The deadline was extended to January 1, 1924.
1923 American Railway Association Interchange Rule 3, Section (f): After January 1, 1924, no refrigerator car equipped with brine tanks will be accepted from owner unless provided with suitable device for retaining the brine between icing stations.
"What is not clear is whether this also applied to ice bunkers, as opposed to ice tanks. Does anyone know the answer to this?"
Strictly cars equipped with brine tanks.