Pollock, Vande Sande & Priddy
Measuring the concentration of substances suspended in a liquid
 This invention relates to improvements in measuring the concentration of suspended substances in a liquid, the substances consisting of components of different geometrical size. The liquid is flowing in a pipe and is illuminated transverse to its flow direction by one or more light sources. A detecting means is arranged to detect light spread by the suspended substances in the liquid in another direction than that of the illuminating incident radiation. This detecting means delivers two electrical signals, the first of which represents a D.C. level measured during a predetermined time and corresponding to a detected level of luminous intensity. The second signal represents the number of times during the same said predetermined time that the detected level of luminous intensity has exceeded a definite discriminator level. The equation of the first signal is Ug = cPF + dFF and the equation of the second signal is UF = aPF + bFF, where a, b, c and d are constants, b is substantially less than a, c and d; and PF represents the concentration of suspended material in excess of a certain definite geometrical size; and FF the concentration of suspended material below the same size. The signals from the detecting means are fed to an evaluation means to develop an output signal, which is representative of the sum S = PF + FF of the total concentration of substances of the flowing liquid during the predetermined time. As an alternative, the evaluation means also develops output signals, representative of the concentration of PF and FF separately. 
Svenska Traforskningsinstitutet
G
G01N
inventional
Jan Gerdt Lennart
Hill Fladda Eriksson