• Four I/O slots
  • Eight relay control outputs
  • Eight virtual inputs and outputs
  • On-screen and web page graphing
  • Ethernet for remote access
    • Internet, LAN or optional Modbus/TCP
  • UL, CSA, IEC & EN


The Walchem W900 Series flow controller has a large display with icon based programming, making setup easy. With multiple language support, the Walchem W900 provides simple setup no matter where you business takes you. You can use the display for on-screen and web page graphing of sensor values and control output status or access that data remotely.

The Walchem W900 Series can also email alarm messages, datalogging reports, graphs, or system summary reports. Universal sensor input provides flexibility; the same controller can be used with almost any type of sensor needed. Four input / output slots allow complete flexibility in adding sensors, analog inputs, analog outputs and LPR corrosion sensors. Eight relay control outputs, eight virtual inputs and eight virtual outputs allow the controller to be used in a wide variety of applications.

Complete flexibility in the function of each relay

    • On/Off setpoint
    • Time proportional control
    • Pulse proportional control (only with 4-20mA or pulse solid state opto outputs)
    • Flow proportional control (only with 4-20mA or pulse solid state opto outputs)
    • PID control (when purchased with 4-20 mA or pulse solid state opto outputs)
    • In-range or out-of-range activation
    • Probe wash
    • Timer-based activation
    • Activation based upon the state of a contact closure
    • Timed activation triggered by water contactor or paddlewheel's accumulated total flow
    • Activate with another output
    • Activate as a percent of another output's on-time
    • Alarm
    • Spike set point
    • PPM volume
    • Target PPM
    • Flow meter ratio
    • Volumetric blending
    • Disturbance variable control

For Cooling Tower and Boiler applications:

  • Biocide timer
  • Boiler blowdown on conductivity using intermittent sampling