PIPING SYSTEM WITH WATER STORAGE TANK INTERPOSED, AND CHANGEOVER VALVE USED FOR THE PIPING SYSTEM

PROBLEM TO BE SOLVED: To provide only one changeover valve used for changing over flow passages and improve cost performance in a piping system in which water passage to a water storage tank and water discharge therefrom are prohibited at emergency by providing a changeover valve which is rotatable inside a valve box and has a valve body provided with two flow passages with a partition wall. SOLUTION: Water is normally fed into a water storage tank from a first flow passage 8 through an opening 3b. The water flows from the water storage tank through an opening 3c and a second flow passage 9. A valve body 6 is turned by 90 degrees at emergency. The first flow passage 8 is made to correspond to the water passage openings 3b, 3c, while the second flow passage 9 is made to correspond to the water passage openings 3a, 3d. When the pressure of the flowing passage is lowered to a specified valve or lower, a piston inside a cylinder is shifted by changing over the flow passages by means of first and second pilot valves, and a valve body 6 is turned. The water fed to the valve body 6 is flowed from the opening 3a directly to the opening 3d. The water inside the water storage tank is secured without flowing while communicated with the first flow passage 8.