chapter  57
Ultrasonic Flowmeters
Pages 16

Flow is one of the most important physical parameters measured in industry and water management. œere are various kinds of žowmeters available, depending on the requirements deŸned by the di¥erent market segments. For many years, di¥erential pressure types of žowmeters have been the most widely applied žow measuring device for žuid žows in pipes and open channels that require accurate measurement at reasonable cost. In markets like waterpower, water supply, and irrigation, however, žow must be measured without any head losses or any pressure drop. œis means there are no moving parts, no secondary devices, nor any restrictions allowed. Two types of žowmeters presently fulŸll this requirement: electromagnetic and ultrasonic žowmeters. Whereas ultrasonic ¦owmeters can be applied in nearly any kind of žowing liquid, electromagnetic žowmeters require a minimum electric conductivity of the liquid for operation. In addition, the cost of ultrasonic žowmeters is nearly independent of pipe diameter, whereas the price of electromagnetic žowmeters increases drastically with pipe diameter.