Joseph J Mcdonald9426 Garnet Falls Ln, Humble, TX 77396

4449101, May 15, 1984

Oct 22, 1982

6/435903

Anthony S. Canzoneri - Kenner LA
Joseph V. McDonald - Metairie LA

Process Development, Inc. - Kenner LA

G01N 2760

324453

An ultrasonic streaming current detector for developing, on a continuous basis, an electric signal which is a function of the charge condition existing in a stream containing charged particles. The present invention has a cross shaped housing having a cross member and a longitudinal member containing a pump chamber having a reciprocating piston on a pair of signal generating electrodes. A fluid injection connection is provided to the base of the longtudinal member. The piston pumps a sample stream within the pump chamber, creating a reciprocating shear force against the sample stream, generating an electric signal across the electrodes. The generated signal is representative of the average electric charge of the suspended particles in the sample stream. To prevent buildup of sample particles in the pump chamber, which would bias the signal, a periodic wash backflow of a fluid is injected into the pump chamber, preferably at a point opposite the point of sample fluid injection. This jet wash purges the pump chambers, maintaining the accuracy of the sample stream.