Operating Like a Pump – Flow cannot be achieved: This warning occurs when a flow control valve is set to an automatic set value that is higher than what the flow would be without a control valve.  The valve is operating like a pump because it has to put energy into the system to achieve that flow rate.

Calculated dP is Outside of Allowable Range: This warning occurs when PIPE-FLO calculates the pressure drop across the control valve to be outside the allowable dP range specified by the user in the Control Valve dialog box.