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Open Channel Flow Measurement for Water Treatment Plant


Clean water measurement or any other fluid that flows through a pipe is easy because such fluids flow through a pipe, and you can run it through a flow meter. On the other hand, water treatment measurement is different because it doesn’t flow through a pipe. Since such flow measurement deals with dirty fluids that can clog the pipe, it must be measured in an open channel. 

This post explains the various ways of measuring waste water in a water treatment system or plant. Read on for more insights on this. 

Water Treatment Flow Meters 

Several flow meters are suitable for measuring wastewater in water treatment plants. Examples of such flow meters include microwave, radar technology, and ultrasonic flow meters. Open channel fluids measurement meters work by emitting and receiving signals pointed directly at the fluid that is being measured. After that, the sensor will then calculate the velocity or the measured fluid level by processing the time taken for the original signal to return to the sensor. 

This makes it easier to calculate flow rate using a proper formula since the information combines with the known physical characteristics of the channel. Another way to measure wastewater is by installing a flow meter and level sensors inside the steam or channel. Such flow meters are called area velocity flowmeters. These two instruments work together to calculate hydrostatic depth and velocity. The results will be fluids measurement. Other effective methods of measuring wastewater include laser or time of flight. 

How Does an Open Channel Flow Meter Work? 

There are several components found in an open channel flow meter, each with particular functions. The work of the wetted component as the primary device is to restrict the flow of the fluid downstream. By doing this, the liquid location will start rising either within the flow or upstream. The level of the liquid goes higher as the flow increases. To sense flow level, a transducer is fixed near or on the primary device. Measuring the flow level and reading the flow rate is done by an electronic flow transmitter that uses the signal from the transducer. 

In open channel flow measurement, several categories of flow meters are used. Flow meters restrict the flow of liquid as it falls downstream, weirs that direct the flow of liquid over an obstruction that looks like a dam, and channel narrowing flumes. When measuring the flow of fluid in an open channel, it is hated to use methods or flow meters used in pipes. Flumes, which are special devices, are necessary for measuring flow rates in open channels. Among the widely used flumes for measuring open channel flow rates are Parshall flumes. They are the best devices because they monitor flow rates permanently. These flumes are commonly used to measure and control irrigation water run-off, industrial process discharge, and sewage treatment plant effluent and influent. 

Open channel fluids measurement devices are used in many applications, including manholes in sewage pipes, rivers, canals, and streams. In addition, flumes have self-cleaning designs for cleaning grits and other heavy solids found in the liquid. 


The flow measurement industry has numerous kinds of flow meters, including those used to measure open channel water sources. These types of flow meters are used in water treatment plants for measuring the level of wastewater. Some of these flow meters, such as the ultrasonic flow meter, are quite durable because they don’t contact the measured fluid.