In the flow measurement industry, ultrasonic flowmeters and open channel flowmeters are widely used. However, many people confuse their application scenarios, resulting in wrong selection, inaccurate measurement, and failure to pass compliance acceptance. This article clearly explains their differences and selection methods in plain language.
1. Core Definition: Cross Relationship, Not Parallel Relationship
They are classified in different dimensions and cannot be regarded as two opposite products:
· Ultrasonic Flowmeter: Classified by working principle. It uses ultrasonic waves to measure flow, divided into pipe type and ultrasonic open channel type.
· Open Channel Flowmeter: Classified by application working condition. It is specially designed for measuring the flow of open channels and non-full pipes with free water surface, adopting three detection methods: ultrasonic, radar, and Doppler.
The real difference lies not in the probe principle, but in application scenario and measurement method.
2. Two Core Differences
2.1. Different Application Scenarios
Pipe-type Ultrasonic Flowmeter Suitable for closed pipelines and full pipe flow, such as tap water, circulating water, industrial and chemical pipelines. It cannot be used for open ditches.
Open Channel Flowmeter Specially used for open channels and non-full pipe flow, including sewage channels, irrigation channels, natural rivers, and municipal drainage channels.
2.2 Different Working Principles
Pipe-type Ultrasonic FlowmeterIt directly uses ultrasonic waves to measure water flow velocity, and calculates flow rate combined with the pipeline cross-sectional area, without any auxiliary equipment.
Open Channel Flowmeter
· Ultrasonic / Radar type: Measure water level, and calculate flow according to the standard flume and weir formula.
· Doppler type: Measure water level and flow velocity at the same time, calculate flow directly without flume or weir.
3. Quick Selection Guide
· Closed pipeline & full water flow → Choose pipe-type ultrasonic flowmeter, high precision and easy installation.
· Open channel & non-full water flow → Choose open channel flowmeter:
o Standard site with available flume construction → Select Ultrasonic / Radar type
o Irregular channel, no space for flume, backwater phenomenon → Select Doppler type
4. Summary
The fundamental difference is whether it is suitable for open channel conditions.Closed pipeline chooses ultrasonic flowmeter; open channel chooses open channel flowmeter.
Select the right open channel flowmeter type according to actual site conditions, ensuring accurate measurement and full compliance, and avoid typical selection mistakes.
