常用农业灌溉水表精确性及耐砂耐冻测试评价

Evaluating Accuracy and Duration Sediment of Wear Test and Frozen Treatment of Agricultural Common Watermeters

针对农业灌溉用水计量设备计量误差问题,对常用的液封式可拆卸垂直、水平螺翼和干式可拆卸水平螺翼、防堵塞水表和超声波流量计进行水力性能试验,并在含砂率1/10 000、1/5 000、1/1 000条件下对水表进行500h磨损试验和在-5、-10、-15℃进行50h的冻胀试验。结果表明,各水表水力性能稳定,在不同含砂率下误差率符合农业灌溉计量要求;2种液封式水表误差率变化趋势相近,2种干式水表误差率趋势类似;4种水表在3种含砂率条件下磨损500h后,误差率没有超过±5%(国家规定允许误差范围)。对误差率趋势拟合分析发现,在含沙率为1/10 000、1/5 000、1/1 000的条件下,试验用的液封式可拆卸垂直螺翼水表和液封式可拆卸水平螺翼水表在使用2.6、2.6、1.68a后误差率大于5%;干式可拆卸水平螺翼水表和干式可拆卸防堵塞水表在使用1.8、1.76、1.76a后误差率大于5%,不再适合灌溉计量。水表冻胀后未损坏则对精度没有多大影响。

Common flowmeters,water seal detachable vertical woltmann flowmeter,water seal detachable horizontal woltmann flowmeter,no water seal detachable horizontal woltmann flowmeter and no water seal detachable preventing blocking flowmeter were used to study their hydraulic performances under three different sediment content（1/10 000,1/5 000 and 1/1 000）.500 hours wear tests of four common flowmeters with the three different sediments contents and a trial of frozen 50 hwith the temperature of-5 ℃,-10℃,-15℃ were carried out.The results showed that hydraulic performances of flowmeters were reliable and error rate was permissible in agricultural water measurements according to national regulation.However,the changing tendency of flowmeters error was fitted with curve linear.Error rate would be greater than 5% after water seal and no water seal flowmeters worked 2.6,2.6,1.68 years and 1.8,1.76,1.76 years on the condition of 1/10 000,1/5 000 and 1/1 000 sediment content,respectively.Moreover,frozen treatments had no significant influence on flowmeter accuracy.