Flow determining apparatus for process fluid at regulating device

摘要

The apparatus has a regulating device (1) which includes a pneumatic drive (3), a regulating element (4), a regulation pressure sensor unit (5) and a device (7) which measures the position of a cut -off valve. Firstly the dependence of the position of the valve with respect to the regulation pressure with no fluid flow is detected, then the flow force acting, during operation on, on the pneumatic drive is detected. The characteristic flow curve is determined as a function of the position of the cut-off valve. The instantaneous flow resulting from the passage of the process fluid is determined in a computing unit (11) by detecting the existing regulation pressure and the position of the cut-off valve.