An examination of BS3680 4C (ISO/DIS 4369) on the measurement of liquid flow in open channels — flumes

The Environment Agency (EA) of England and Wales requires consent holders to install flow-monitoring equipment to measure the flow of sewage or trade effluent where it exceeds 50 m3/day. The daily totalized discharge has to be recorded to +/−8%.The open channel measurement standard on rectangular throated flumes has been reviewed. There were very little experimental verifications of the theoretical discharge equation and predicted uncertainty. The assumed flow behaviour in the throat is not consistent with observation and computational fluid dynamics analysis. Tests were carried out in the laboratory using a flume with a throat width of 100 mm. The experimental evidence suggested that the operation limits imposed by the standard could be too conservative.