Safety code
requires OPD (Overfilling Protection Device) valve
The National Fire Protection
Association safety code for propane tanks (NFPA 58)
required tanks with a capacity of 4 to 40 pounds that
were manufactured after September 30, 1998, to have an
OPD (Overfilling Protection Device) valve. This includes
the 20-pound propane tank used in full size barbecue
grills. A tank without an OPD valve cannot be refilled.