In-line pipe device checking by short period analysis of transient tests

In this paper the results of laboratory transient tests concerning the interaction between a pressure wave and an in-line device are discussed. Transients are generated by means of a fast and complete closing of an end valve and pressure measurements are carried out just upstream of the maneuver valve. The main effect of the device on the pressure time-history — hereafter, referred to as pressure signal — is a sharp increase caused by the pressure wave reflection. Three experimental setups are considered in which different in-line devices are installed (i.e., a ball valve, a butterfly valve and different sized orifices). The pressure signal is analyzed in the time domain and a reliable evaluation of the device location is obtained by means of wavelet functions. Furthermore, on the basis of the value of the pressure increase, the status of the device can be determined; experimental results are synthesized in a dimensionless diagram. Finally, criteria for the use of the obtained results in other pipe systems are discussed.