ford truck guy wrote:
If they are older and still in perfect shape , they should not be refilling them if they do not have the OPD valve...
Snippet from "propane 101" site -
OPD stands for "overfilling prevention device" or "overfill protection device" and is required on all 4 to 40 pound DOT cylinders in vapor service..
I believe all tanks manufactured after October 1998 are required to have the OPD. The OPs tanks should have the OPD but are now beyond their 12 year date which would mandate a safety inspection and recertification sticker.
Inspection info here