Laboratory Analysis of a Piston-Actuated Pressure-Reducing Valve under Low Flow Conditions

Marco Franchini,Valentina Marsili,Stefano Alvisi,Riccardo Zarbo

doi:10.3390/w12040940

Abstract

The effectiveness of pressure-reducing valves (PRVs) for optimal pressure management of water distribution networks (WDNs) is proven, but problems and operational limitations have been highlighted by some recent experiences. In this study, we analyse the functioning of a piston-actuated pressure-reducing valve (PA-PRV) with a mechanical pilot which is subjected to low-flow regimes, a condition that is often observed in real water distribution networks. The analyses were carried out by means of laboratory tests featuring two sets of experiments, i.e., (a) by testing the behaviour of the PRV when a pre-established initial value and subsequent variation of flow rate occurs in the system and (b) by testing the PRV against a temporal series of flow rates observed at the inlet section of a real district metered area. The first set of tests showed that the PA-PRV tends not to maintain pressure at the imposed set-point and exhibits an unstable behaviour characterised by significant pressure oscillations under some flow rate conditions. The second set of laboratory tests showed that the anomalous behaviour identified in the first set of tests can occur under ordinary operational conditions of a network.

Highlights

The processes of managing and monitoring complex water distribution networks are often based on the design of district metered areas (DMAs) [1,2,3,4,5,6,7], which allow for easier system monitoring and leakage identification [8]
The PA-pressure-reducing valves (PRVs) analysed in this study (Figure 1a,b) consists of a plastic valve and an independent control unit made up of a pilot and a three-position selector of the C-valve type marketed by Saisanket
Two distinct tests were conducted in order to characterise the behaviour of the piston-actuated pressure-reducing valve (PA-PRV) with

Summary

Introduction

The processes of managing and monitoring complex water distribution networks are often based on the design of district metered areas (DMAs) [1,2,3,4,5,6,7], which allow for easier system monitoring and leakage identification [8]. In the partitioning of networks into DMAs, pressure-reducing valves (PRVs), or devices capable of regulating the pressure downstream of the installation site, are often used [9,10,11,12]. Among the different types of pressure-reducing valves, the most common are diaphragm valves, in which the pressure-regulating device operates in a direction transverse to the flow. The pilot that regulates the downstream pressure control mechanism can be mechanical or remotely electronically controlled, even in a real-time mode

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