Handling Installation Issues with Non-Standard Parshall Flumes in Ultrasonic Open Channel Flowmeters

When using an ultrasonic open channel flowmeter, the installation of the flume also has certain standards. Improper installation can lead to various problems and directly affect the measurement results of the open channel flowmeter.

Below are the actual issues encountered during the use of a non-standard Parshall flume self-installed by our customer, along with the subsequent corrective measures taken.

Cause: Non-standard Parshall flume (no throat section), inlet and outlet reversed, upstream channel too short (only 1 m from the outlet to the flume, with a slope causing excessive flow velocity and preventing free-flow conditions).

Description: http://image0.chunsuns.com/site501/upload/album/20170727/2017072713363975568625.jpg

The horizontal distance from the crossbar below the probe to the projection directly beneath the probe is approximately 5 cm, and the vertical distance from the probe to the crossbar is approximately 37 cm.

Description: http://image0.chunsuns.com/site501/upload/album/20170727/2017072713465136294439.jpg

Solution:

We advised the customer to re-machine the Parshall flume and install it properly (extend the channel, ensure free-flow conditions before water enters the measurement flume, and keep a 30 cm diameter clear area directly below the probe).

Temporary measures taken:

At the outlet, place a brick 0.6 m from the inlet of the Parshall flume to stabilize the water flow; change the instrument probe type to 1 and reduce the short gate value to 75 to minimize the impact of the crossbar on measurements.

If you have any questions during the use of ultrasonic open channel flowmeters, please call our hotline: 0591-28082552. Fuzhou Dayu Electronic Technology Co., Ltd. will be dedicated to serving you!