Chemical concentration control system for fluid circulators

In a closed chemical solution circulator including a solution tank, a power operated pump with an intake pipe connected to said tank and a discharge pipe for delivering said solution into an enclosure communicating with said tank;

• a chemical concentration control system for the automatic addition of quantities of a chemical for maintaining a predetermined concentration thereof within said tank comprising:
• a diverter and chemical addition pipe connected to said discharge pipe for continuously sampling the solution in said discharge pipe and thereafter disrecting same into said tank;
• an aspirator having a fluid inlet and outlet connected into said diverter pipe and having a vacuum additive intake pipe;
• a chemical concentrate storage source connected to said vacuum additive intake pipe ;
• a normally closed solenoid valve interposed into said vacuum additive intake pipe between said aspirator and said chemical concentrate storage source;
• an electronic controller connected to said solenoid valve;
• and a flow-through conductivity cell interposed within said diverter and chemical addition pipe upstream of said aspirator responding to a predetermined chemical concentration of the sampling fluid in said diverter pipe and connected to said electronic controller for signaling said electronic controller at a set value without energizing said solenoid valve;
• said conductivity cell including probes projected into the sampling liquid within said diverter pipe and monitoring the conductivity thereof;
• a predetermined reduction of said chemical concentration in said diverter pipe interrupting said signal;
• said controller automatically energizing and opening said solenoid valve responsive to said signal interruption thereby allowing said chemical concentrate to be drawn form said source into said aspirator and circulated to said solution tank;
• the average diameter of said diverter pipe being less than said discharge pipe so that the volume of sampling solution flowing through said diverter pipe at any time is appreciably less than the volume of flow through said discharge pipe;
• the flow through said diverter pipe being continuous so that said aspirator is continuously calling for the chemical concentrate;
• the restoration of said predetermined chemical concentration reactivating the signal of said conductivity cell to said controller and automatically closing said solenoid valve thereby completing the cycle of replenishment.