As an example, if part of the flow path is restricted, the downstream pressure will reduce starting from the restricted area. This is called pressure loss. Pressure loss is energy loss and not only is downstream pressure lowered, but flow, and flow velocity are reduced as well.
The pressure difference between pressure gauge A and pressure gauge B is pressure loss. Also, pressure loss is not just caused by restriction. Piping that becomes longer also causes pressure loss in a similar way.
When pressure loss occurs on a production line, the flow of circulating cooling water is lowered, causing a variety of quality and production problems. To correct this, it is best to remove the part that is creating the pressure loss. However, in most cases pressure loss is reactively handled by raising the pressure generated by the circulation pump and/or raising the power of the pump itself. This measure results in a waste of energy and unecessary cost.
SOURCES OF TROUBLE FOR FLOW METERS