| abstract |
PCT No. PCT/JP90/00648 Sec. 371 Date Dec. 31, 1990 Sec. 102(e) Date Dec. 31, 1990 PCT Filed Jun. 29, 1989 PCT Pub. No. WO90/00155 PCT Pub. Date Jan. 11, 1990.The present invention offers a piping system for supplying ultra-pure water, which comprises a circulation tank to store primary pure water from a primary pure water producing unit, a pump for sending the primary pure water from said circulation tank, an outward pipe, one end of which is connected to a final purifying unit to purify primary pure water from said pump to ultra-pure water, a plurality of connection pipes, each end of which is connected to the other end of said outward pipe, a branching pipe connected between the middle of said connection pipe and the ultra-pure water using unit and having a branching valve to adjust the water quantity, and a return pipe connected between the other end of said connection pipe and said circulation tank, characterized in that means for controlling the output of said pump is provided to keep the water pressure at constant level by detecting the water pressure in said outward pipe, thereby supplying a constant quantity of ultra-pure water to the ultra-pure water using unit at all times, and that ultra-pure water of ultra-high purity can be stably supplied by preventing counterflow from the return pipe to the ultra-pure water using unit. |