Selecting an ultrasonic flowmeter correctly requires a precise understanding of the technical parameters of the measured fluid and the actual conditions of the process pipeline, as well as a clear determination of the metering class. While choosing an ultrasonic flowmeter is the right choice, even after clarifying the required metering class, it is crucial to accurately understand the technical parameters of the measured fluid and the actual conditions of the process pipeline. Specifically, the following are some key considerations:
First, the properties of the measured medium are crucial. Different media require different ultrasonic flowmeter models, taking into account factors such as the corrosiveness and explosion-proof rating of the medium. If measuring corrosive media, the measuring tube and transducer should be made of stainless steel or other materials that meet the requirements.
Second, the amount of gas or particulate matter in the medium also needs to be considered. Gas or particulate matter in the medium can hinder the transmission of the acoustic pulse, affecting the time difference measurement, leading to unstable flow measurement and increasing measurement error. To address this issue, a gas separator should be installed upstream of the flowmeter to ensure timely removal of gas. Doppler ultrasonic flowmeters are recommended for media with high gas content or high particulate content.
Third, the medium's operating temperature also needs to be considered. Clarifying the measured fluid's common, minimum, and maximum temperatures allows manufacturers to select measuring tube materials, transducer materials, cable types, and sealing materials based on operating requirements. Temperature ratings are typically categorized as below 60°C, below 150°C, and below 200°C. To ensure fluidity and prevent buildup, the flowmeter must be properly heated and the heating temperature controlled.
Fourth, the medium's operating pressure is also a factor to consider. The fluid's common operating pressure and maximum design operating pressure are factors to consider. Ultrasonic flowmeter manufacturers generally select models based on the maximum design operating pressure to ensure safe operation.
Fifth, determine the accuracy level and number of channels. The accuracy level of the selected flowmeter should be determined based on national energy metering instrument requirements and actual production conditions, with an emphasis on achieving a reasonable price-performance ratio. The number of channels is primarily determined by the required measurement accuracy level and on-site pipeline conditions (such as straight pipe length, flow pattern, and gas content of the measured medium). For ultrasonic flowmeters with the same time measurement accuracy, more channels improve low-velocity performance and increase the measuring range. Sixth, flow range: When selecting an ultrasonic flowmeter, consider factors such as the fluid's typical flow rate, minimum flow rate, and maximum flow rate. For flowmeters with the same time measurement accuracy, a higher number of channels results in better low-flow performance and a wider measurement range.
Sixth, Flow Range
When selecting an ultrasonic flowmeter, factors such as the fluid's typical flow rate, minimum flow rate, and maximum flow rate should be comprehensively considered. For flowmeters with the same time measurement accuracy, a greater number of channels improves low-flow performance and increases the measuring range.
Seventh, Remote Information Transmission: If remote information transmission is required, the signal type and communication method must be clearly defined to ensure compatibility with the selected ultrasonic flowmeter.
Eighth, Process Pipeline Flange Standards: When selecting an ultrasonic flowmeter, the process pipeline flange standards must be clearly defined, such as GB national standards, JB Ministry of Machinery standards, HG Ministry of Chemical Industry standards, SH Petrochemical standards, JIS Japanese standards, and ANSI American standards. Furthermore, matching connecting flanges must be selected for ease of installation.
Ninth, Considering the Straight Pipeline Length Requirements and Process Pipeline Layout: When selecting a flowmeter, the straight pipe length requirements and the appropriate layout and installation method of the process pipeline should be comprehensively considered. For example, it's important to understand the length of the straight pipe sections, whether there are elbows, expansion joints, tees, pumps, valves, etc., the type of valve and whether it's used for flow regulation, whether the installation is horizontal, vertical, fixed, or mobile, whether there's bidirectional flow, and the frequency and pattern of flow direction changes. For flowmeters using the same principle and design, the greater the number of channels, the higher the measurement accuracy, but the shorter the straight pipe section required.
Tenth, Power Supply Requirements: When selecting an ultrasonic flowmeter, it's important to clearly understand the on-site power supply (AC or DC, battery), the voltage range, and the controller interface requirements, such as the number of wires.
In summary, selecting an ultrasonic flowmeter requires consideration of multiple factors, including the properties of the measured medium, the gas or particulate content of the medium, the material of the measuring pipe, the measurement accuracy and metering rating, and the installation environment. Only with a comprehensive understanding of these factors can one correctly select an ultrasonic flowmeter.