Studies on Optimization of Safety Measure in Pipeline for Field Irrigation with Automatic Control Valve

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This dissertation presents a series of studies conducted for investigating applicability of automatic control valves to guarantee the safety in field-irrigation pipelines The final goal of the studies is to achieve a pressure reduction on field irrigation pipelines using automatic control valves. For the purpose, the studies focused on the following two main objectives ; (1) in natural down-flow pipelines, establish a pressure control technique by applying automatic control valve and safety valve, and (2) in pumping pipelines, investigate for water column separation and establish a technique of controlling water hummer pressure by applying check valve. These techniques contribute to reduce maximum pressure in the pipeline and thus enable a safe use of low-cost polyvinyl-chloride pipes for field irrigation pipelines. Also, it allows to construct pumping pipeline system without having conventional facilities for negative pressure measures.