The clear plastic 'hose' referred to is a plasticized PVC. It is extremely tough and damage resistant. An accidental bump is not going to cause damage. But it does melt easily! Heed the advice, keep the upper and lower valves closed. An added benefit of doing this is you can easily estimate the day's fuel burn when you open the valves for a check and see the level change. For those contemplating installing this system, you should use a medium wall, small bore (~1/4") tube. Avoid the very thin stuff. A popular brand is 'Tygon'. Bob Kassal Chateau de Mer