安全弁による低圧化システムの圧力制御対策(III) : 自動減圧弁を直列設置した場合

抄録

A field test was conducted on the stability of a pressure-reducing system equipped with two automatic control valves installed in series in a test pipeline in Ohno Mountain of Kagoshima Prefecture. The effects of automatic control valves on pressure reduction in pipeline were investigated via experiment. In the experiment, conventional and/or new type automatic control valves were installed in the pipeline, singly or in series, with safety valves. The result indicated: (1) conventional control valve does not have enough ability to cut the secondary pressure occurs when no flow of water, (2) on the other hand, new type valve can satisfactory cut the secondary pressure, and multi-level pressure reduction by series installation of the valves is possible, (3) applying safety valve in downstream side of control valves is effective to avoid transmitting water hammer pressure having fast propagation speed, (4) it is necessary to have a safety valve fitted on the upstream side of the new type valve, as the new type valve closes quickly and thus pressure increase on the upstream side of the control valve upon valve closure, (5) when the control valves are installed in series, applying the safety valves in both upstream and downstream sides of each control valve (i.e. install in total four safety valves) can control pressure in between the control valves and thus increases safety of the system.