Hydraulic characterization of PVC-O pipes by means of transient tests

Molecularly oriented PVC (known as PVC-O) was developed as an improvement to conventional unplasticized PVC (or PVC-u). For a given nominal pressure, the biaxial orientation of the pipe material allows to double the tensile strength and increase flexibility and resistance to cyclic fatigue, with a reduction in weight. Although the PVC-O pipes are produced and used since late 80s, the behavior of such pipes during transients is not well characterized in literature. In the paper we present the results of transient tests carried out on a PN16 DN110 pipe and generated by maneuvering an automatically controlled butterfly valve. The experimental setup has been installed at the Water Engineering Laboratory of the University of Perugia, Italy. Both time domain and frequency domain analyses are performed. The pressure wave speed is evaluated experimentally by means of pressure measurements. Information deriving from strain gauges is used to verify and characterize the actual viscoelastic behavior of PVC-O pipes.