| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent the occurrence of the reverse flow of water and to perform smooth pumping-up to an elevated place by a method wherein the ends on both sides of an inner pipe made of synthetic resin having an inner peripheral surface covered with fluorine resin and an outer pipe made of synthetic resin having an air layer located therebetween are interconnected through a joint having a check valve and an inner surface covered with fluorine resin. SOLUTION: The inner peripheral surface of an inner pipe 1 made of a synthetic resin is covered with a fluororesin, such as polytetrafluoroethylene, and an outer pipe 3 made of a synthetic resin is formed through an air layer 4 on the concentric circle of the outside of the inner pipe 1. The pipes 1 and 3 are connected to the two ends of the pipes 1 and 3. A joint 9 having a check valve 10 is arranged and the inner surface of the joint 9 is covered with a fluororesin cover layer 2, such as polytetrafluoroethylene. For example, when potable water is fed to a part between mountains having height of 1000mm or more, freezing is prevented from occurring, frictional resistance of the inner surfaces of the pipes 1 and 3 is reduced, and the reverse flow of water is prevented from occurring to perform smooth pumping up to an elevated place.</p> |
