NEW "OPD" VALVE MANDATED FOR ALL
SMALL PROPANE CYLINDERS
OPD Valves Required on all Cylinders 4# - 40# by April, 2002

On April 1, 2002, federal law requires update of all 4 to 40 pound vertical non-stationary Department of Transportation (DOT) propane cylinders to be equipped with new Overflow Protection Device (OPD) valves.   It will be illegal to refill most portable cylinders not equipped with the new style OPD-fitted valves.  The previously ubiquitous POL (bullet nose, left-hand thread) valve has been replaced by a new valve fitted with an overfill prevention device (OPD) and a Type 1 fitting for connecting pigtails.

How it Works
opd_4steps.gif (17013 bytes)
  1. Liquid propane (dark blue in illustration at left) fills the cylinder through the OPD valve.



  2. At a safe level, the float cam (yellow) triggers the pin (orange) to fall into the recess of the cam, sealing this path off and preventing any more liquid propane from entering the cylinder.



  3. The propane builds up pressure in the chamber (center spring) and pushes the piston arm up to form a seal, effectively stopping the filling process.



  4. Using propane from the cylinder resets the OPD for the next fill.

It's Easy to Identify the New OPD Valve

The new OPD valve is distinctive in several ways, both by it's markings, and it's shape:

OPD Identification

The 1998 Liquefied Petroleum Gas Code section of National Fire Protection Association (NFPA) Standard 58 called for the installation of OPDs on all 4 to 40 pound vertical DOT cylinders manufactured after September 1, 1998.  The 2001 version of the same code states that horizontal cylinders are exempt from an overfill protection device (OPD) retrofit as long as the cylinder was manufactured prior to Oct. 1, 1998.  That means that these cylinders can be legally recertified after 12 years without making modifications.  The tanks mounted to motor homes (designated as ASME tanks) are not subject to this regulation.

There are limits on how much propane can be put into a cylinder.  Because propane expands, as it gets warmer, it is important not to exceed a cylinder's proper filling limit.   A properly filled cylinder will have a vapor space left in the top of the cylinder to allow room for expansion of the liquid with a change in atmospheric temperature.  Currently proper refilling is dependent on the operator; it is possible to overfill the cylinder by inaccurate weighing, ignoring the presence of liquid propane at the fixed-level gauge, or relying on a float-type dial gauge.  The OPD helps prevent potentially hazardous conditions caused by cylinders that may have been overfilled.

OPDs are intended to reduce the danger associated with these kinds of possible errors, by automatically stopping the refilling process without the operator's intervention.  The new OPD valves prevent overfilling of gas cylinders, making filling and using gas cylinders safer than ever before.  The OPD consists of a float mechanism attached to the cylinder's refilling valve that cuts off the flow of propane as soon as the propane level reaches the container's rated 80 percent liquid capacity.  The presence of an OPD does not relieve the operator from the duty of determining the proper fill level by one of the other standard methods.

OPD-equipped cylinders have a special triangular hand wheel, which cannot be removed, and are marked with the letters "OPD" on the valve body.  They are equipped with Type 1 fittings, also called Quick Connection Coupling (QCC) fittings that allow connections of the pigtails without the use of tools.  This coupling is designed so that no propane flows unless the mating connector is fully inserted.  These cylinders use the plastic hand nut that fits over the 1 5/16 inch outside right hand Acme threads for the new-style hose fittings.  QCC-equipped valves also have inside left-hand threads that will accommodate the old POL fittings.

Retrofitting older POL equipped propane cylinders is possible in most cases; however, the expense may be close to the same as purchasing a new cylinder instead.  It is recommended that you check with your local propane dealer to make sure the correct valve is installed in your old cylinder.  In some cases it is not possible to replace the old valve with an OPD replacement valve.

If you have any questions you should check with your local LP gas dealer.  Remember to properly dispose of any old propane cylinders.  Many companies that sell new cylinders will accept your old ones for disposal (possibly for a small disposal fee).  Do not throw any propane cylinders into the garbage since they are considered a hazardous material.