To provide a connecting tube structure obtained by noticing that installing two differential-pressure connecting tubes outside an exhaust tower satisfies their functions through ensuring that temperature difference between gases due to temperature rise within the two connecting tubes is not higher than a permissible value.
In this gas flow measuring instrument, a differential pressure detector 5 for measuring a differential pressure between the exhausted gases is provided near an outlet end of an exhaust path of a smoke stack or of an exhaust tower 1 for a high-rise structure, etc., and the two differential-pressure connecting tubes 11 and 12 from the pressure detector 5 are connected to a differential-pressure transmitter 6 to measure the flow of the gas based on the differential pressure. The two connecting tubes 11 and 12, comprising metallic pipes laid on the exterior of the exhaust tower 1, are connected/unified by a weld metal part 13, a heat conductive material 14 is disposed between he two connecting tubes 11 and 12, and the unified two connecting tubes and conductive material 14 are coated with a heat retaining/insulating material 15.
TERAKADO JUNICHI
HIYAMA TETSUO
KAKEFUDA KENJI
