Installation diagram

1. Selection requirements:

The installation location of the Doppler flowmeter should have a straight channel with a channel width of 20 times upstream and a straight channel with a channel width of 5 times downstream. Be sure to choose a stable flow installation point.

Due to actual channel limitations, some sites have installation locations where the upstream cannot reach 20 times the direct channel and the downstream cannot reach 5 times the direct channel. The minimum requirement is 5 times the length of the upstream straight channel and 3 times the length of the downstream straight channel, but the problem is that the measurement error increases. The specific amount of this error depends on the site conditions and varies from site to site.

2. Installation requirements at the bottom of the channel:

Sensors should be installed as close to the bottom of the channel as possible. If there is a lot of sediment, silt, water grass, or stones rolling at the bottom of the channel, the installation position can be raised to avoid the probe being covered by sediment and water grass, or being impacted by stones, causing damage to the probe.

3. Selection of horizontal installation position

For channels with a width of less than 20 meters, if they are rectangular channels, they should be installed at 15-20% of the entire channel width. Because it is installed at this location, it is closest to the average flow velocity in the horizontal direction of the entire channel.

Installation of trapezoidal channel: The sensor is installed at the junction of the slope and the bottom edge, also known as the "foot of the slope". At the same time, it is necessary to ensure that the sensor is 20 centimeters below the minimum water level.

4. The sensor should be facing the direction of water flow directly

5. For garbage or floating debris coming from upstream, a grid should be installed on the upstream channel for filtering, and the distance between the grid and the sensor should be more than 5 times that of the channel.

6. Installation conditions and locations inside pipelines or culverts

① Installation inside the pipeline can be measured as long as the minimum water level exceeds 20 centimeters above the sensor and the inner diameter of the pipeline is greater than 500 millimeters. It is not required to fill the tube, and it can also be measured in a non full tube state. It is also necessary to choose a place with stable water flow for installation. The upstream of the installation location should have a straight channel with an inner diameter of 20 times the pipeline, and the downstream should have a straight channel with an inner diameter of 5 times the pipeline.

② Choose a location with stable water flow for installation. Areas with unstable water flow can result in unstable measurements and significant errors. There will be two situations: first, there will be large fluctuations in the data up and down; Secondly, the measured data is smaller than the actual value;

③ Consider the sediment and silt inside the pipeline, and if there is silt, the sensor should avoid it. For garbage or floating debris coming from upstream, a grid should be installed on the upstream channel for filtering, and the distance between the grid and the sensor should be at least 5 times the inner diameter of the pipeline.

7. Installation conditions and location within the river channel

① For wider river channels, such as natural rivers, spillway channels of large reservoirs, ship channels under dams, and spillway channels of hydropower stations, the flow velocity from the two banks to the middle varies greatly. Measuring the flow rate is even more complex because the flow velocity and flow volume are different at different locations.

In this case, in addition to meeting the conditions for installation within the channel, it is generally necessary to collect flow velocity data from multiple points. At least 3 sensors are required, one on each side and one in the middle of the riverbank. For example, dividing a 30 meter river into 10 equal parts on average.

Install sensors on both sides and in the middle of the river, and then connect them all to the same host.

To improve measurement accuracy, it is possible to install 5 sensors.

② Ensure that the minimum water level at the installation point during the dry season is 20 centimeters higher than the sensor.

③ To determine whether the on-site measurement points are suitable for installation, there are many natural rivers where it is difficult to install them with brackets. In order to install sensors, it is even necessary to use excavators to build embankments to block water flow and create a convenient construction site. In this case, it is necessary to consider using ADCP river flow meters for measurement.

8. Installation of water level gauge

The sensor is equipped with a built-in pressure water level gauge, but the pressure water level gauge is prone to blockage, damage, or long-term zero drift, resulting in inaccurate measurement. Other level gauge sensors can be externally connected to the instrument for water level measurement. Specific agreement docking with dealers.

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