METHOD FOR MEASURING LEVEL OF POWDER

PURPOSE:To measure a deposition level continuously with high accuracy by mounting a purge type probe for pressure detection in the proper place of a vessel and the space part in the vessel, and detecting the fluctuation in the differential pressure of the purge back pressure detected with said probe. CONSTITUTION:A dust catcher 1 captures the dust in a waste gas and accumulates the same therein. When the level thereof attains the control position of an upper limit or above, a sluice valve 1a is opened to discharge the dust down to the control position of a lower limit. Through-holes 11, 12 are provided in the control positions of the upper and lower limits where the dust on the side wall 1c of the catcher 1 accumulates, and purge type probes 21, 22 for pressure detection are inserted and installed in these through-holes respectively. A through-hole 13 is provided in the sufficiently high position where the dust on the wall 1c does not accumulate, and a purge type probe 23 for pressure detection is inserted therein. The purge back pressure detected with the probes 21, 22, 23 is converted to an electric signal with transmitters 6, 7. The electric signal transmitted therefrom is operated 100, displayed 101, and is fed to a discharge setter 102, so that the valve 1a is opened or closed by a driving circuit 103.