| 摘要 |
PURPOSE:To enable the measurement of dust concn. over a wide range with high accuracy irrespectively of the change in the dust concn. by measuring the pressure drop of the filtered and captured dust with a pressure sensor, exchanging a filter when the pressure drop of the dust exceeds a prescribed value and measuring the concn. of the dust always at a specified flow rate. CONSTITUTION:The drop P0 by the suction of a suction pump 10 is measured with a pressure gauge 16, and the filter loss P2 consisting of the total value of the drop P0 by the suction of the pump 10 and the pressure drop P1 of a constant flow rate device 12 is measured with a pressure sensor 18. A control section 20 to which the filter loss signal from the sensor 18 is inputted stops the pump 10 and exchanges a filter 14 when the filter loss P2 attains the prescribed value, that is, the limit value at which a set flow rate Q0m<3>/min, can be maintained by the device 12. The pump 10 is driven again after the exchange and the suction of the dust in the atm. air is started. |
