Re: Grey gas line problem

[amuller]

Interesting subject. I’ve been using generic auto-parts-store fuel line which is SAE J30R7 and costs around $1.25/foot. This doesn’t have a liner in the inner tube. Most of what I’ve been reading says one should use SAE J30R9, which is often sold as "fuel injection" hose, and costs maybe 50% more. This does have more layers and one has to pay attention to that when inserting fittings. Some of the black "fuel hose" sold at big box stores, etc, is actually PVC, not rubber, and isn’t marked as compliant with any SAE standard. I don’t use this. It appears that the auto industry is moving, or has moved, to teflon (PTFE)hose, but nylon has also been used for fuel lines. There is a set of Coast Guard fuel hose type numbers that tie back to a different set of SAE standards. There are EPA standards for permeation. Blah, blah, blah, all very complicated and confusing. I’ve seen 50-60 year old hoses that seem serviceable, and two-year-old ones failing….