Measurement Principle and Application of Portable Ultrasonic Flowmeter

When ultrasonic waves propagate in a fluid, their propagation speed or phase is affected by the flow rate of the fluid. By properly processing the ultrasonic signal passing through the fluid, the flow rate of the fluid can be detected, thereby obtaining the flow rate of the fluid. The time difference method ultrasonic flow meter uses the time difference caused by the different propagation speeds of ultrasonic waves in the forward and reverse flow in the fluid to measure the flow rate of the fluid and calculate the flow rate.

Portable flow meters are mainly used in two aspects: on the one hand, flow measurement of pipelines without metering; on the other hand, online flow calibration of pipelines with metering. When measuring flow, the probe must be installed correctly. For example, the probe should be correctly installed on the pipeline and the probe cable should be connected to the host. After power on, input pipeline parameters (including pipe outer diameter, pipe material, pipe wall thickness, fluid type, installation method, etc.), and correctly install the probe according to the installation distance to make the portable flow meter enter the normal measurement state. We can see various flow displays, including instantaneous flow. Precautions for probe installation, the installation position of the probe, that is, the pipeline conditions of the flow to be measured, have a considerable impact on the measurement accuracy. The position that meets the following conditions should be selected:
1. The length of the upstream straight pipe section is more than 10D, and the length of the downstream straight pipe section is more than 5D.
2. Within 30D on the upstream side, there is no interference with the flow.
3. The pipeline must be filled with fluid and there should be no bubbles.
4. When the pipe diameter is 200mm or larger, the Z method should be selected. When the appropriate installation spacing cannot be provided or the fluid concentration is very high, the Z method should also be selected.
Portable flow meters are widely used and have almost completed the measurement and online calibration of all new water meters, playing an irreplaceable role in metering management.