Dust content meter - for measuring dust in circulating gases

摘要

In an appts. for measuring the dust content (by wt) in a circulating gas, comprising in known manner (a) a sensitive element having a dust-collecting surface and a resonance frequency which is a function of the mass of dust collected (b) a circuit for maintaining the sensitive element in vibration (c) means for projecting the dust onto the collecting surface of the sensitive element and for measuring the vibration frequency of this element, contains in addn. (d) the sensitive element consists of a stretched ribbon with means for self cleaning. More esp. the ribbon is fixed and the self-cleaning means comprises a switching element for causing the vibration-maintaining circuit to change from a state corresp. to normal amplitude vibration to a state in which the amplitude of vibration of the ribbon is sufficiently high to remove the layer of dust collected on the ribbon.