# Known Flow

Design flow rate set to Zero on Input Tab: If you have a Known Flow node defined in a system with a flow rate of zero, it is recommended that the status of this node is set to "Off or Closed" as this will help model convergence. It is also recommended that a Known Flow node is not modeled directly in series with a relief valve, flow control valve or a centrifugal pump which is set to Auto Size on design flow rate, as this will potentially over-constrain the system or duplicate an already defined flow rate. Try switching the Known Flow node for a Known Pressure boundary node. If any of the above is unclear or you require any further information, please contact us at: support@fluidflowinfo.com.