The application areas of ultrasonic open channel flowmeter include urban water supply diversion channels, power plant cooling water diversion and drainage channels, sewage treatment inflow and discharge channels, chemical liquids and wastewater discharge from industrial and mining enterprises, and channels for water conservancy projects and agricultural irrigation.
When installing ultrasonic open channel flow meters, you should pay attention to the following five points:
1. Ultrasonic probe installation form and precautions
The installation methods of open channel ultrasonic flowmeter include bracket installation and flange installation. If site conditions permit, try to install flanges. Flange installation makes it easier to adjust the sound direction of the probe perpendicular to the water surface. Since ultrasonic flowmeters have emission angles and blind zones, the distance between the high water surface and the bottom surface of the probe must be greater than the blind zone distance. When selecting the installation location, do not be too close to the edge of the channel and install it above the center line of the channel to avoid affecting the normal operation of the instrument.
2. The measured flow velocity is based on the premise that the channel flow pattern is fully developed, that is, the straight section of the channel (pipe) is required to meet the requirements.
3. When there are insufficient straight lines on site, it is necessary to compensate for the impact of oblique flow on the accuracy of flow velocity measurement by setting up sound channels across the measurement section.
4. If there are weirs, gates and other facilities before and after the on-site measurement section that disrupt the vertical flow pattern, multi-channel measurement should be used to accurately measure the surface average flow velocity. The determination of the number of sound channels and the height of the sound channels must be based on the measurement accuracy requirements, and the minimum water level, maximum water level and working water level must also be considered.
5. For channel-type flowmeters, it is important to accurately measure flow velocity and water level, but the error that often has the greatest impact on flow measurement is the channel cross-sectional area (such as sedimentation at the bottom of the channel, uneven channel walls, and inconsistent channel widths). and other errors). Therefore, what is particularly proposed here is that the control of channel cross-sectional area errors must begin with the channel civil engineering design.