RECOMMENDED FOR: Liquid or gaseous propane, butane or any combination of these two mixtures. Can be used for natural gas (not to exceed 50 psi) under certain conditions such as: open/outside areas and well ventilated factory buildings (if local building codes permit). CAUTION: Not recommended for residential, office buildings or as fuel line hose on compressed natural gas vehicles. Contact Denver Product Application (303) 744–5070 for inspection and assembly testing information. Warning: Do not convey LP Gas over +140°F (60°C).