Manchester Tank Co, who makes the Westy tanks, has a link
on their site to Vegas Trailer Supply:
http://vegastrailer.com/vts/odp.html

Note it states that the requirement applies to "portable,
upright propane cylinders...."

There is also a link of that page, back to Manchester Tank's
web for a page on how OPD works.

                            Richard A. Jones
                            Boulder, Colorado
                            '81 Vanagon   Mr Bus
                            '87 Syncro Westy   El Jefe