All propane cylinders between 4 and 40 lbs. in the state of Texas are required to be fitted with an overfill prevention device (OPD).  If a bottle is overfilled with propane, a potentially dangerous situation exists.  The OPD requirement prevents cylinders from being overfilled.  Mallory Propane keeps OPD valves in stock and can install them for you if your cylinder requires it.

		Non-OPD Old style propane cylinder valve
		OPD Valve is equipped with Overfill Prevention Device
	How the OPD Works

Q: What is an overfilling prevention device?

A: As defined by the National Fire Protection Association's Pamphlet 58 - LP-Gas Code, 1998 Edition (Code), it is..."A safety device that is designed to provide an automatic means to prevent the filling of a container in excess of the maximum permitted filling limit." Typically, the overfilling prevention device will appear as part of a cylinder valve that is installed as a complete unit into the cylinder. The cylinder valve will have either a CGA 791 (ACME threads) or a CGA 810 (push-pull, quick disconnect) connection device.

Q. What does the Code require?

A. For propane cylinders* in the 4 lb. through 40 lb. propane capacity range, the Code requires for them to be equipped with an OPD, as follows: New cylinders for vapor service which are fabricated after September 30, 1998; as cylinders are requalified after September 30, 1998 through March 31, 2002; effective April 1, 2002, before a cylinder is filled.

Q: How can an OPD be identified when it is installed in a cylinder?

A: Listed (e.g. Underwriters Laboratories, Inc.) OPD's are easily recognizable by observing their unique trilobular handwheel. The handwheel is connected to the valve stem in a tamperproof manner for the purpose reducing the possibility of putting a user at risk by an attempt to interchange an OPD handwheel on to a conventional non-OPD valve. It should be noticed that the valve stem on a non- OPD equipped cylinder is not easily matched with a standard trilobular OPD
handwheel. Mallory employees who fill cylinders take care in observing whether or not a cylinder that appears to be equipped with an OPD, actually is.

Q: Is an OPD intended to be an aid in the filling of a cylinder?

A: The device is designed to only be a backup in the filling of a cylinder. With an OPD equipped cylinder, the traditional procedures of filling by the weight or volumetric methods should be followed.
Note - Prior to the Code's requirement for the use of OPD's, early non-uniform valves were introduced into the marketplace. Thousands of these valves had conventional handwheels and were not marked as now required by the UL listing. While the safety features of these early OPD valves is not being questioned, those who fill small propane cylinders should be aware of these valves still being in service. In time, through normal attrition, these first generation OPD valves will fade from use by attrition.

Q: Is the requirement for OPD's a mercenary ploy by those in the propane industry to take advantage of consumer's pocketbooks?

A: This is a good question and deserves a direct answer which is.... no. Those marketers who fill propane cylinders for customers have had virtually nothing to do with the advent of the OPD. The term "virtually" is used as there were a few highly concerned and industry active propane marketers who became involved in resolving issues which surrounded the advent of OPD's, including a reasonable time frame for the introduction of these new safety devices into the marketplace.

Q: I have a horizontal cylinder on my recreational vehicle. Are OPD's available for that kind of service?

A: The 2001 edition of NFPA 58 (the LP-Gas Code) recognizes that horizontally oriented cylinders that were manufactured prior to October 1, 1998, are unable to be retrofitted with the OPD's. As a result of this fact, the Code now exempts these cylinders from having to be retrofit with OPD valves. Any such cylinder must have a label affixed to it to inform the user and the refiller that an OPD valve is not installed. (Note: This provision was not contained in the 1998 edition of NFPA 58.)

Q: Why do some propane retail marketers fill cylinders that would normally be required to be requalified and have an OPD installed, whereas other marketers require the OPD to be retrofit on the cylinder before they refill it?

A: Mallory's and other propane marketers of integrity care about the handling and use of cylinders that they refill, knowing that the families of consumers deserve the best and safest service that can be offered. If a propane marketer elects to do otherwise, that choice speaks for itself. Also keep in mind that some states or jurisdictions have not adopted the 1998 or later editions of NFPA 58.

Q: In another state I recently had a cylinder filled for my deer hunting camp and they didn't mention anything about an OPD. Are there laws different from this state?

A. The Code is revised by the National Fire Protection Association every three years. Virtually all of the individual United States of America have adopted the Code as their rules for propane applications, but not necessarily on a uniform basis as to a particular edition. So, as the OPD requirements first appeared in the 1998 edition of the Code, not all states have updated their propane rules to that edition. Again, it is expected that all cylinders in the 4 lb. through 40 lb. capacity range will eventually be equipped with an OPD.