Measures the mass concentration of the dust grain in the vapor the manner

摘要

PURPOSE: To allow more accurate measurement of the mass of dust particle by stopping an oscillator when the dust particles are filtered to be captured and stopping the filtering/capturing when the frequency is measured thereby eliminating the measurement error caused by the dynamic and static pressures being applied to a filter paper holder and preventing the separation and rescattering of dust particles due to accelerating vibration. ;CONSTITUTION: An ON/OFF valve 22, e.g. a two-way valve or a three-way valve, is turned ON/OFF automatically by a control signal delivered from a data processor 16. The filtering/capturing operation of gas is stopped at the time of measuring the variation (difference) of resonance frequency of a fork oscillator (sensor) 1 before and after a predetermined gas capturing period. A switch 23, i.e., a noncontact switch employing a thyristor, for example, turns the feedback signal of an automatic gain regulation amplifier 14 ON/OFF automatically in synchronism with the control signal. During the gas capturing period, the feedback signal is closed to stop resonance of the oscillator 1. During the frequency measuring period, the feedback signal is opened to cause resonance.;COPYRIGHT: (C)1995,JPO