tatest
Oklahoma
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Joined: 05/14/2005
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A permanently installed tank does not use the OPD valve used on DOT spec LPG cylinders. It already has two types of overfill protection devices installed.
Long before OPD valves became a requirement on portable LPG cylinders, automatic shutoff fill valves were standard equipment on ASME LPG tanks. The tank on your '93 Santara should have the shutoff valve.
This automatic shutoff on ASME tank fill valves, and the OPD valve on cylinders, are two different devices with a similar function on fill, but different construction because the OPD valve is also a vapor withdrawal valve. Nobody can or will put the OPD valve on your tank, it is the wrong valve and it won't even work as a OPD in that application.
On stationary tanks, the automatic shutoff in the fill valve is secondary overfill protection. The primary protection is the liquid bleed valve; those were on tanks before the automatic shutoff was employed, and they are still on tanks, and supposed to be used as the primary safety device.
Portable cylinders can't use a liquid bleed valve, where it would have to be installed is just not safe for a cylinder that gets thrown around and banged against things. Before the OPD, the only overfill protection was procedural, i.e. the tank goes on a scale.
Tom Test
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mowermech
Billings, MT
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All the portable cylinders I have ever used or owned have had a liquid bleed valve. Even the three new ones I have do, it is built in the valve, and must be opened with a screwdriver. The 30#'ers on the 5er have it, too. So did the horizontal tanks in the truck camper I had. All seven of these tanks (or bottles) had/have OPD valves.
I haven't had a bottle weighed for filling for over 30 years!
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Kendas
Tucson AZ
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ASME tanks (those permanently mounted to the frame) DO HAVE AN OPD "system" and have had so for many years (35 at least). It is different from the ones mandated on portable bottles and cylinders but operates in a similar manner as in... This system does not allow you to fill the tank more than 80% full of liquid propane. It starts venting liquid propane from a "valve" that is permanently built into the tank at the 80% full level. The actual valve may not be "physically at the 80% level but the tube opening is internally. Also due to the type of construction (much heavier duty steel) these tanks do not have to be re-certified unless there is visible damage or extensive deep rusting (minor surface rust is okay).
Note: There are places that fill propane (other than propane companies) but, have "mis-trained" their personnel and will not fill ASME tanks because they don't have the "triangle" hand knob (that is mandated on the bottles/cylinders) on the tank. The placards that are prominently displayed at most of these places show only bottles and cylinders and show nothing about ASME tanks. Since they do show "tanks" on these placards, they won't fill them since "your tank" doesn't have this knob.
* This post was
edited 10/08/08 10:21pm by Kendas *
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Buffett Fan
Belmont Hills Philadelphia
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Joined: 08/25/2008
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Thank you all for the good advise. I'll check the condition of the tank.
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