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.

中文翻译：

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低流量条件下活塞驱动减压阀的实验室分析

减压阀 (PRV) 在优化配水网络 (WDN) 压力管理方面的有效性已得到证实，但最近的一些经验凸显了问题和操作限制。在这项研究中，我们分析了活塞驱动减压阀 (PA-PRV) 和机械先导阀的功能，该阀受到低流量状态，这种情况在实际配水网络中经常观察到。分析是通过实验室测试进行的，包括两组实验，即 (a) 通过测试当系统中出现预先设定的初始值和随后的流速变化时 PRV 的行为，以及 (b) 通过根据在实际区域计量区域的入口部分观察到的时间序列流速测试 PRV。第一组测试表明 PA-PRV 往往不会将压力保持在施加的设定点，并且表现出不稳定的行为，其特征是在某些流速条件下会出现显着的压力振荡。第二组实验室测试表明，在第一组测试中发现的异常行为可能发生在网络的正常运行条件下。