John, et-al;

NFPA 58 specifically exempts horizontal tanks.

"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 retrofitted 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."

The 2001 edition of NFPA 58  modified requirements to exempt
horizontal cylinders manufactured before October 1, 1998, from
requiring OPDs. Also exempt are cylinders used for industrial trucks,
industrial welding and cutting gases (these cylinders must be labeled
with their use).

  Sources:  <http://www.npga.org/i4a/pages/index.cfm?pageid=534> and
<http://www.nfpa.org/itemDetail.asp?
categoryID=303&itemID=19333&URL=Research%20&%20Reports/Fact%20sheets/
Vehicles/gas/fuel%20safety/Propane%20cylinder%20overfilling%
20prevention%20devices%20(OPD)>

To be legal, all you need is a label.

On Jun 25, 2007, at 4:55 PM, John Middelkoop wrote:

> You can just switch to a plain filler valve and outage valve
> (manual safety, stop filling when it starts coming out the outage)
> but its
> not US legal.