Instrument and process for testing contamination in liquid materials

Claim 1

APPARATUS FOR CONTINUOUSLY TESTING THE IMPURITY LEVEL OF LIQUID MATERIALS, COMPRISING A CHAMBER ADAPTED TO RECEIVE A CONTINUOUS FLOW OF LIQUID UNDER TEST AND FOR DISCHARGING SAID LIQUID, MEANS ASSOCIATED WITH SAID CHAMBER FOR ILLUMINATING THE LIQUID UNDER TEST WITHIN SAID CHAMBER DURING ITS PASSAGE THERETHROUGH, PHOTOCELL MEANS FOR RECEIVING ONLY SCATTERED LIGHT DERIVED FROM ILLUMINATION OF CONTAMINANTS IN THE LIQUID IN SAID CHAMBER, PASSAGE MEANS CONNECTED TO SAID CHAMBER AND HAVING A DIVIDED FLOW PATH INCLUDING A FILTER IN ONE BRANCH THEREOF AND A VALVE FOR CONTROLLING THE DIRECTION OF FLOW WHEREBY FILTERED OR UNFILTERED LIQUID IS CONTROLLABLY SUPPLIED TO SAID CHAMBER, OUTLEET PASSAGE MEANS THROUGH WHICH THE LIQUID PASSES OUT FROM THE CHAMBER, ELECTRICALLY CONTROLLED METER MEANS FOR INDICATING THE OUTPUT OF SAID PHOTOCELL, A BALANCING CIRCUIT OPERATIVELY COMBINED WITH SAID METER AND SAID VALVE WHEREBY SAID ELECTRICALLY CONTROLLED METER MEANS IS CALIBRATED TO ZERO IMPURITY DURING PASSAGE OF FILTERED FLOW THROUGH SAID CHAMBER, SAID BALANCING CIRCUIT INCLUDING A TIMED SWITCHING MEANS WHICH PERIODICALLY OPERATES SAID VALVE TO ALTERNATELY PASS FILTERED FLUID WITH WHICH THE PHOTOCELL IS CALIBRATED AND UNFILTERED FLUID WHICH IS TO BE TESTED TO THE CHAMBER, AND MEANS FOR DEACTIVATING SAID BALANCING CIRCUIT TO PROVIDE A METER READING RESPONSIVE TO SAID PHOTOCELL MEANS DURING PASSAGE OF UNFILTERED LIQUID FLOW