What is an OPD?

OPD - a Required National Standard.

What is an OPD?

OPD is an abbreviation for Overfilling Prevention Device, which is part of national fire and safety standards designed to make the use of propane even safer. An OPD is a safety feature that prevents small propane cylinders from being overfilled. After January 1, 2003, all propane cylinders 4 pounds to 40 pounds MUST be equipped with an OPD. This standard is required by the National Fire Protection Association . Horizontal cylinders manufactured before October 1, 1998, are exempt, as are cylinders used for industrial trucks, industrial welding and cutting gas.

Who Requires OPD?

The National Fire Protection Association (NFPA) develops standards for the safe use of propane and other fuels nationwide. It is NFPA's Pamphlet 58, the standard for propane dealers, which requires OPDs. Thus, propane dealers are required to follow this requirement. 

Why have an OPD?

There are limits on how much propane can be put into a cylinder. A properly filled cylinder will have a vapor space left in the top of the cylinder to allow for expansion of the liquid due to change in temperature. An Overfilling Protection Device is a means of assuring that cylinders are not overfilled.

What can happen when a cylinder is overfilled?

An overfilled cylinder may not have enough vapor space left in the top of the tank if the liquid propane expands when exposed to warmer temperatures. This can cause an increase in cylinder pressure and create potentially hazardous conditions such as:

  • The pressure relief valve may open, discharging propane from the cylinder
  • Propane liquid could enter a piping system, resulting in higher than normal pressure to appliances.

How can I tell if my cylinder has an OPD?

All new cylinder wrappers and/or warning labels will include this information. Most cylinders with OPDs have special triangular hand wheels with the words OPD imprinted. Some OPDs, however, were produced before the letters OPD were required on the valve handles and valve bodies. If you have questions, check the wrapper or label or ask your propane dealer to identify the type of valve on your cylinder.  For additional information and pictures click HERE.

What happens if I don't have an OPD installed on my cylinder?

As of January 1, 2003, cylinders without OPDs cannot be refilled.

How does an OPD work?

During the refilling process, when the proper level of propane is reached, a valve inside the cylinder closes thereby stopping the flow of propane into the tank.

Who can I contact if I have other questions?

Your local propane dealer wants you to understand these standards and would like to make compliance with them as easy and inexpensive as possible. If you want additional information, your local propane dealer will do everything possible to assist you.