Open channel flow meters deal with free flowing, or free gravity flowing, open channels. The flowing liquid of these channels have a top surface open to the air. The cross-section of their flow is based only on the shape of the shape of the lower side of the channel through which they flow.
Open channel: a flow of fluid where there is one free surface present, and the only pressure on it comes from gravity
There are many different types of open channel flow, depending on the environment in which they are found. For example, some have no changes in the depth of liquid where others have a constant, unsteady flow.
Open channel flow meters monitor the relationship between the depth of the liquid and the flow rate. In contrast, most other flow meters use mass or volumetric data to determine flow rate. In order to do their work, open channel flow meters typically use ultrasonic transducers, pressure sensors, shaft encoders, or special radars that can function in a free surface.
Other types of open channel flow measurement include: area/velocity flow measurement, level to flow measurement (measured at a designated point behind a weir, in a flume, or other hydraulic structure, using various secondary devices), dye testing (when operators add a known amount of dye (or salt) per unit time to a flow stream. After complete mixing, they measure the concentration; the dilution rate equals the flow rates.), and Acoustic Doppler velocimetry (used to record instantaneous velocity components at a single point with a relatively high frequency, uses the Doppler shift effect to measure the velocity of particles in a remote sampling volume).
Open channel flow meters work where traditional flow meters cannot. Specifically, traditional flow meters cannot work where the top surface of a liquid is exposed to the open air. Most commonly, open channel flow meters are used in water and wastewater industries, as water and wastewater are by and large the most common liquids found in open channel flows. However, they are also popular anywhere open channel flows are found. They can even measure flow in rivers.
Regardless of your exact application, if you seek an open channel flow meter, you need to find a supplier that is knowledgeable on the subject, skilled, and reliable. Find that supplier by browsing the websites of those flow meter manufacturers and distributors that we have listed on our website, and reaching out to one or more of them with your specifications.