PURPOSE: To detect a leaking place by draining water from a water supply pipe, supplying halogen gas under pressure, forming small holes which penetrate through a road pavement member at certain intervals, and successively setting halogen sensors in close to the small holes.
CONSTITUTION: Water is drained from a warm water pipe 12 by opening and closing a prescribed valve. Small holes (10mm) having a length reaching the crushed stone ballast are drilled at a certain interval (1-2mm) on a pavement member 10. When SF6 is supplied into a pipe 12, and gas pressure is increased, SF6 leaks from the defective place 14 of the pipe 12, and leaks out to the road surface from a small hole 13 which is closest, passing through the crushed stone ballast layer 11. The sensor 17 of a halogen sensing device 16 is set close to each small hole 13, and the SF6 leaking place is determined. Since, the small hole 13 from which SF6 leaks at first is closest to the defective place of the pipe 12, the pipe 12 is exposed by digging within a certain range around the small hole 13, and the defective place 14 can be discovered.
YOSHIDA SHOTARO
MOCHIZUKI MASATAKA
MASUKO KOICHI
ITO MASAHIKO
SAITO YUJI
