（1） Installation points
1. Selection of flow measurement section: A straight section with stable water flow, no eddies, no tributaries merging, and regular section shape should be selected. Generally, the length of the straight section upstream of the flow measurement section should not be less than 10 times the width of the channel, and the length of the straight section downstream should not be less than 5 times the width of the channel. Installation near bends, steep slopes, and gates should be avoided.
2. Sensor installation position: The flow velocity sensor of the ultrasonic flowmeter should be installed in the middle and upper part of the flow measurement section, ensuring that the sensor is perpendicular to the direction of the water flow, the emitting end faces upstream of the water flow, and the height from the water surface needs to be adjusted according to the measurement range; The water level sensor should be installed in a stable flow rate area to avoid being affected by waves and eddies. When used in conjunction with a weir, it should be installed at a specified distance upstream of the weir (such as 2-3 times the water head upstream of a triangular weir).
3. Installation requirements for weirs: The installation of weirs should ensure that they are level and aligned with the axis of the open channel. The weirs or throat of the trough should be smooth and flat to avoid water leakage; After installation, water level flow calibration is required to ensure that it matches the theoretical formula.
4. Wiring and Grounding: The wiring between sensors and secondary instruments should be standardized to avoid parallel laying with strong electrical lines and reduce electromagnetic interference; The equipment needs to be reliably grounded with a grounding resistance not exceeding 4 Ω, especially in outdoor scenarios where lightning protection and grounding measures should be taken.
（2） Maintenance points
1. Regular cleaning: Non contact sensors (such as ultrasonic probes) need to be regularly cleaned of surface dust, oil, and scale to avoid affecting measurement accuracy; Contact sensors (such as electromagnetic flowmeter electrodes and flowmeter propellers) need to be regularly cleaned of attached sediment and suspended solids, checked for wear and corrosion, and promptly replaced with damaged components.
2. Regular calibration: It is recommended to calibrate the open channel flowmeter every 6-12 months, using methods such as standard volume method and flow meter comparison method to adjust equipment parameters and ensure measurement accuracy meets requirements; For weir channel flow meters, it is necessary to regularly check whether the weir channel is deformed or silted, clean it in a timely manner, and recalibrate it.
3. Equipment inspection: Regularly check whether the power supply system, wiring terminals, and communication modules of the equipment are normal, and check whether the instrument display data is stable; Outdoor equipment needs to check whether the protective shell is intact and whether the waterproof and lightning protection devices are effective.
4. Data maintenance: Regularly backup measurement data, check whether data transmission is stable, and promptly handle data anomalies; For devices with data storage capabilities, it is necessary to regularly clean the storage memory to avoid memory overflow.