NFPA 58 addresses the flood issue as Jerry pointed out.

JP, according to the NAtional Propane Gas Assn, I have water at 8.34 lbs/ gallon and propane (1.50 vapor density) at 4.2 lbs./ gallon.

Of course, in flood areas, they need to secure the coffins in the cemetary, too. Seriously, if you are inspecting a house along a river and the house has a high water mark from frequent floods, I would be looking not only for tank restraints but to see if the regulators are above this floor line. If they appear to have gone swimming, they should have been replaced as with any gas control that has been submerged.

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