100lb propane tanks on their side?

lay it in its side and strap it down and make sure it has a cap installed. its not going to hurt anything

Reef W wrote:

but what’s the real risk if you have the cap installed over the valve?

The risk is in the position of the safety valve.
This brief paragraph addresses the concerns when transporting. (even though it is written about fork trucks)

Though forklift cylinders are designed to be used in the horizontal position, make sure customers know the cylinders should still be transported in the vertical position. When secured to a forklift, there is a pin that locks the cylinder into a specific position, keeping the pressure relief valve in the vapor space of the cylinder. If transported on its side, the cylinder may roll and shift the pressure relief valve to the bottom, in the liquid space of the cylinder.

I’ll just leave this here.

Thanks for the warnings. Turns out leaving the heat on in cabin for the last week didn’t use as much as I thought it might and we’ll be fine until Monday when they’ll come drop off two new tanks.

What would have cause the initial ignition?

I’m far from an expert in this area, but when we first got the cabin we would haul those lp tanks laying down and strapped down BUT we made sure the cap was securely on.

I wouldn’t call it a general rule but those are usually hauled and stored up right

I welded for alot of years using coverage gas. Most wasn’t flammable, but when there full that’s somewhere around 2300 lbs of pressure, caps needed to be on to protect the valve, like propane or you had an aweful powerful missile