TESTING VALVE ASSEMBLIES

摘要

A method of determining flow through a valve includes determining a first differential pressure across the valve (410). The valve is bypassed (420) and a second differential pressure is determining across the valve (440). A flow decision is determined for the valve based on comparison of the first and second differential pressures (450) (fig. 4). A method of testing a relief valve in a reduced pressure backflow preventer assembly includes determining a first differential pressure across an upstream check valve during a no flow condition (1020). The upstream check valve is bypassed (1030) for the purpose of opening a relief valve, and a zone vent is opened (1050) (Fig. 10).