Patent ID: 6109097
Filing Date: 2000-08-29
Classification: G01F,G01N

Abstract:
A method of measuring the quantity of particulate matter of known dielectric properties suspended in a gaseous carrier medium for transport in a predetermined direction within a pipe, comprising:providing in the pipe an electrically conductive measuring path;establishing from a first position of the measuring path at least one electric alternating field below the characteristic cut-off frequency of wave propagation;initially measuring, with a predetermined load of particulate matter in the measuring path, any attenuation of the electric alternating field as a function of frequency at a second position of the measuring path axially remote from the first position thereby to determine the parameters of the measuring path;determining a curve representative of the attenuation of the electric alternating field relative to frequency between the first and second positions;defining as a reference value a substantially linear range from the steepest slope of the curve between an upper threshold value with an associated low frequency and a lower threshold value with an associated high frequency, andproviding an undetermined load of suspended particulate matter in the measuring path;deriving a value representative of the quantity of particulate matter of the undetermined load by determining the shift in frequency over the substantially linear range.