The current shortcomings of the ultrasonic flowmeter are mainly that the temperature range of the measured flow body is limited by the temperature resistance of the ultrasonic energy exchange aluminum and the coupling material between the transducer and the pipeline, and the original data of the sound transmission speed of the measured flow body at high temperatures is incomplete. At present, China can only be used to measure fluids below 200℃. In addition, the measurement line of the ultrasonic flowmeter is more complex than that of the general flowmeter. This is because the flow rate of the liquid in general industrial metering is often a few meters per second, and the propagation speed of the sound wave in the liquid is about 1500m/s, and the change in the velocity of sound brought by the change in the flow rate of the measured flow body is also 10-3 orders of magnitude. If the accuracy of the measurement flow rate is required to be 1%, the measurement accuracy of the sound speed needs to be 10-5 ~ 10-6 orders of magnitude, so there must be a perfect measurement line to achieve, which is also the ultrasonic flowmeter can only be practical application under the rapid development of integrated circuit technology.
(1) The temperature measurement range of the ultrasonic flowmeter is not high, and generally can only measure fluids with a temperature below 200 ° C.
(2) Poor anti-interference ability. It is easy to be disturbed by ultrasonic noise mixed with bubbles, scaling, pumps and other sound sources and affect the measurement accuracy.
(3) The straight pipe section is strictly required for the first 20D and the last 5D. Otherwise, the dispersion is poor and the measurement accuracy is low.
(4) The uncertainty of installation will bring a large error to the flow measurement.
(5) Scaling of the measurement pipeline will seriously affect the measurement accuracy, resulting in significant measurement errors, and even no flow display in severe cases.
(6) The reliability and accuracy level is not high (generally about 1.5 ~ 2.5), and the repeatability is poor.
(7) Short service life (general accuracy can only be guaranteed for one year).
(8) Ultrasonic flowmeter is by measuring the fluid speed to determine the volume flow, the liquid should measure its mass flow, the instrument measurement of mass flow is obtained by multiplying the volume flow by the artificially set density, when the fluid temperature changes, the fluid density is changed, the artificially set density value, can not guarantee the accuracy of the mass flow. Only when the fluid velocity is measured at the same time, the fluid density is measured, and the real mass flow rate can be obtained through calculation.
(9) Doppler measurement accuracy is not high. The Doppler method is suitable for biphase fluids with not too high heterogeneous content, such as untreated sewage, factory discharge fluid, dirty process fluid; It is not usually suitable for very clean liquids.
Post time: Dec-18-2023