By setting up the device, as outlined in the first five steps above, you can determine whether an initial zeroing is needed, or if it is good to go. An initial zeroing may be necessary upon installation. If you are seeing flow, this could be the valve leak-by as described above.īrooks Instrument MFCs are zeroed at the factory. Remove VOR open command and/or set point.
For analog devices, monitor the output signal and adjust the zero potentiometer until zero is achieved.Alternatively, digital devices can be re-zeroed using a service tool from Brooks Instrument - Brooks Expert Support Tool (BEST).The LED indicator turns green when the zero process is complete. For digital devices, press the zero button until the LEDs indicate the device is re-zeroing.Allow 30 seconds minimum for stabilization.This will fill the lines up to the shutoff valve and pressure will equalize across the MFC. Close a downstream shutoff valve and open the MFC valve using a setpoint or valve override (VOR) open command.It is preferable to zero at process conditions (meaning inlet pressure should be the same as the normal device operation).Allow for a warm-up time of at least 45 minutes to get to normal operating temperatures.To zero your device, it is recommended that you follow these steps: Keep in mind, MFC valves are precision control valves, not positive shut off valves, so a small amount of valve leak-by may exist. The best way to know when your MFC needs to be re-zeroed is to see if there is flow signal (positive or negative) at a zero flow condition. To ensure the best possible accuracy, it is recommended to zero the MFC at initial installation and periodically thereafter. While mass flow controllers (MFCs) from Brooks Instrument are known for stability and minimal long-term drift, the flow signal or process variable (PV) from an MFC may drift over time.
There are many reasons why this can occur, such as a change in mounting orientation, ambient temperature, or process pressure.
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