Ultrasonic flowmeters are instruments that use ultrasonic technology to measure the flow velocity or volume of fluids and are widely used in industries, municipal services, environmental protection and other fields. Its working principle is based on the characteristics of ultrasonic waves propagating in fluids, and the flow rate is calculated by measuring the interaction between ultrasonic signals and fluid flow.
The types are divided into three kinds:
1.External clamping type (non-invasive type)
The sensor is installed on the outer wall of the pipeline and does not come into contact with the fluid. It is easy to install and suitable for corrosive and high-pressure fluids. However, there are certain requirements for the material of the pipe, the wall thickness and the cleanliness of the fluid.
2. Insertable type
The sensor part is inserted into the pipe, which is suitable for large-diameter or thick-walled pipes, and the measurement is more stable.
3. Pipe section type
It can be directly integrated into the pipeline with high precision, but it needs to be pre-installed and is suitable for new systems.
The installation location of ultrasonic flowmeters has specific requirements to ensure the accuracy of measurement results and the normal operation of the equipment.
The following are some key points of the installation location requirements:
1.The installation location should be as far away as possible from disturbed areas, such as elbows, reducers, valves and throttling devices, etc., to avoid the pressure drop in the fluid causing gas release, weakening the intensity of the ultrasonic signal and generating noise.
2. The transducer can be installed in either horizontal or vertical pipe sections, with priority given to the position where the fluid in the pipe flows upward. When conditions are not available, a pipe section where the fluid flows from top to bottom can be considered, but it is necessary to ensure the back pressure inside the pipe to guarantee the smooth flow of the fluid throughout the pipe.
3. For single-channel ultrasonic flowmeters, to enhance measurement accuracy, it is necessary to ensure that there are no valves, water pumps, throttling holes, etc. that could disturb the fluid within a range of 30 times the upstream pipe diameter.
4. The length of the straight pipe sections before and after the sensor installation position should meet the requirements, such as 10D before and 3D after (some manufacturers require 10D before and 5D after). In cases where the length requirement of the straight pipe sections cannot be met, the upstream straight pipe section should be larger than the downstream straight pipe section.
5. The installation location should be selected on a pipe section with good roundness, smooth inner surface and uniform pipe wall, such as a straight pipe section of 5D on the upstream side and 3D or more on the downstream side. The tested pipeline must be filled with liquid and have sufficient space for installation and operation.
6. It should be avoided to be installed at the highest point of the pipeline system or on vertical pipes with free outlets to prevent gas accumulation from affecting the measurement.
7. For hydropower stations that cannot meet the conditions of straight pipe sections, a cross-channel surface configuration can be adopted and more channels can be used to enhance the representativeness of flow velocity.
The above are some basic requirements for the installation location of ultrasonic flowmeters. The specific installation still needs to be adjusted according to the actual situation on site and the guidance of the equipment manufacturer.