and a pressure operated flow bypass valve.As the flow rate begins to increase fromzero, the fluid flows only through a restrictionnozzle and impinges against a target, whichrotates at the specified flow rate. A switch ismagnetically coupled to the target and actuateswhen the rotation occurs. The switch output isused for alarm or control. The flow valve opens when the flow rate exceeds the actuation rate.This allows the additional fluid flow to bypass therestriction nozzle. The pressure drop is thus limited to a low value at high flow rates