An OPD is a backup safety shutoff device incorporated into the filling valve of a propane cylinder. It is designed to prevent cylinder overfilling in excess of the cylinder's maximum permitted filling limit.

The Hazardous Materials Regulations (HMR; 49 CFR Parts 171 - 180) do not contain specific design requirements for cylinder valves. We have not adopted the OPD requirements into the HMR. It is contained in the National Fire Protection Association's publication "NFPA 58, Liquefied Petroleum Gas Code," 1998 edition. NFPA is not a governmental agency; however, many states have adopted the NFPA Code as state law. You should contact your state or local government agency to find out if your state requires propane cylinders to conform to the OPD requirement.

NFPA 58 requires an OPD on all cylinders with 4 to 40-pound propane capacity that are:

1. Fabricated (manufactured) after September 30, 1998;
2. Requalified after September 30, 1998; or
3. Refilled on or after April 1, 2002.

For most consumers, the OPD requirement applies to their 20 lb gas grill tank.

Exceptions: NFPA 58, 1998 Edition states the OPD requirement does not apply to cylinders used in industrial trucks, including forklifts trucks, or to cylinders identified and used for industrial welding and cutting gases. The NFPA 58, 2001 Edition broadens the provision to include certain cylinders manufactured before October 1, 1998, and designed for use in the horizontal orientation.

The HMR govern the safe transportation of hazardous materials in commerce. Under the HMR, a cylinder is not required to be equipped with an OPD. You should contact the appropriate state or local agency if you have questions concerning your responsibilities relating to a propane cylinder not equipped with an OPD.