Multi-point Acoustic Sensing (MAS) technology makes use of hydrophone sensors placed at discrete distances along pipelines in order to detect third party interference (TPI) and leaks. In fact, any interaction with the pipe generates pressure waves that are guided within the fluid for long distances, carrying information on the source event. Pressure propagation is mainly governed by the absorption coefficient and the sound speed. These parameters are in turn complicated functions of the frequency, the geometrical and elastic parameters of the pipe shell, the elastic parameters of the surrounding medium, and the acoustic and thermodynamic properties of the transported fluid. We have designed several experimental campaigns on oil and gas transportation pipelines, instrumented with a proprietary MAS system. We have defined and simulated an exhaustive set of TPI and leak tests, taking care of the quantitative characterization of the dynamic parameters, especially at the source point. In this paper we describe the experimental work, and we discuss the data processing for the detection of pipe/flow anomalies. The results are also used for the validation of mathematical models of pressure waves propagation in fluid filled pipes.