Behind the panels: Cooling tower panel with bleed valve

This "Behind the panels" blog shows a very simple and economical cooling tower panel with bleed valve.

This version is designed to have a local measurement and control of a conductivity measurement and biocide adding. The panel includes:

• Conductivity sensor

• Sample valve

• Flow switch

• Bleed leg with motorized bleed valve

• Injection point for dosing pump

• Inlet -and outlet ball valves

The conductivity sensor and the flow switch are connected with the small NanoTron controller, which can control 2 relays. Relay 1 is used to control the conductivity based on a setpoint. It will open the bleed valve, once the setpoint of the conductivity is reached and close when the differential value is met. Relay 2 can be used for a biocide adding program or alarming. The biocide program is a settable timer program. A dosing pump is connected to Relay 2 to pump the biocide according the set timer.

The flow switch will interlock any control. A prébleed and bleed lockout prevent draining of freshly added biocide.

With an analog output in the controller, it is possible to send out the measured value in a 4-20mA signal. An injection valve installed in the outlet leg completes the panel to have a plug and play system that limits the installation time on site.