Chilled Water System Dosing Guide (Closed Loop)

A closed chilled water loop should not lose water – in practice it does, through vents, pump seals and make-up. Every litre of make-up dilutes inhibitor, which is why dose has to be maintained, not set once.

The Operating Reality

A commercial or industrial chilled water loop serves air handling units, process coolers and fan coils from a central chiller plant, with a make-up line and a dosing pot or skid.

Why Manual Dosing Falls Short

Dilution and oxygen ingress drive corrosion; warm return temperatures drive biological growth. Inhibitor concentration that drifts below the protection band shows up as fouled coils and a rising approach temperature.

How Automatic Chemical Dosing Fits

• Automatic feed keeps inhibitor inside the protection band continuously, removing the saw-tooth of manual top-up.
• Conductivity and pH feedback let the controller detect make-up-driven dilution and respond on its own.
• Leak alarm within 2 seconds and dry-running protection suit plant rooms that are visited only weekly.

Selection Checklist

• Define the control signal first (pH, ORP, conductivity or flow-proportional) before sizing the pump.
• Size the metering pump to the lowest expected dose with margin, not to the peak dose.
• Confirm chemical compatibility of wetted parts (316L, PVC, PVDF) with every product to be fed.
• Provide containment, leak detection and dry-running protection in the dosing room design.
• Integrate the skid with PLC, DCS or remote telemetry so dose is visible in the control room.

Related Products

• Automatic Chemical Dosing System
• Automatic Condenser Tube Cleaning System (ATCS)
• Constant Pressure Water Make-up System

FAQ

Related Dosing Guides

• Closed Loop Hvac Dosing
• Corrosion Inhibitor Dosing System
• Ph Orp Controlled Dosing System