Discussion: LPG cyclinders dangerous on vans

I have been told that the swap &go etc. lpg cyclinders have a number code 1,2,3,or 4 and some cannot be used on caravans as an insurance claim was rejected because of the use of a cyclinder meant only for bbq use being damaged while on the van draw bar causing a fire burning the front of the van .there is no signage at point of sale warning some of these cyclinders should not be used on caravans can someone shed some light on this topic as i have two swap types on my van at present

Steve, NT