Laboratory Investigations of Combined Vertical Flowmeter and Flow Controllers Used for Irrigation Water Delivery,

摘要

Combined rotameter-type flowmeter and flow-controllers were studied in the laboratory. These devices totalize flow,indicate flow rate,control flow to preset rates over a large range of line pressure,and provide shutoff in single units. Head loss,accuracy,and operational tests were performed on used devices that had been modified in the field to correct totalization inaccuracy noted in previous studies. Tests were also performed on unused new version devices to check compliance with specifications. Further field operation and experience are necessary to fully evaluate mechanical design of the new devices. During laboratory tests operational difficulties such as leakage,failure to internally recognize closure initiation and slowness of or even refusing to control flow were experienced with both versions of the device. (Author)