After clarifying the required metering level, accurately understanding the technical parameters of the fluid being measured and the actual conditions of the process pipeline is crucial for correctly selecting an ultrasonic flow meter.
Meaning Medium Properties:
The selection of flow meters varies greatly depending on the medium being measured. Requirements such as media corrosivity and explosion-proof rating should be considered. For measuring corrosive media, the measuring tube and transducer should be made of stainless steel or other materials that meet the requirements.
Meaning Medium Gas Content or Particulate Matter:
Gas or particulate matter in the medium can hinder the transmission of acoustic pulses, affecting the time difference measurement, leading to unstable flow measurement and increased measurement error. A gas separator should be installed upstream of the flow meter to ensure timely gas removal. Doppler ultrasonic flow meters are recommended for media with high gas content or high particulate matter content.
Meaning Medium Operating Temperature:
Determining the common, minimum, and maximum temperatures of the fluid being measured allows the manufacturer to select the appropriate measuring tube material, transducer material, cable type, and sealing materials according to the operating conditions. Temperature ratings are typically categorized as: below 60°C, below 150°C, and below 200°C. To ensure the fluidity of the medium and prevent wall adhesion, proper heat tracing of the flow meter is essential, and the heat tracing temperature must be controlled.
Medium Operating Pressure:
This includes the fluid's common operating pressure and its maximum design operating pressure. Manufacturers typically select flow meters based on the maximum design operating pressure to ensure safe operation.
Accuracy Class and Channel Number Determination:
The accuracy class of the selected flow meter should be determined according to national requirements for energy metering instruments and actual production conditions, paying attention to a reasonable performance-price ratio. The number of channels is mainly determined based on the required measurement accuracy class and on-site pipeline conditions (straight pipe section, flow regime, gas content of the measured medium, etc.).
Flow Range:
This should be considered comprehensively based on the fluid's common flow rate, minimum flow rate, and maximum flow rate. With the same time-based measurement accuracy, more channels generally result in better low-velocity performance and a wider measurement range.
Remote Information Transmission:
When remote information transmission is required, the signal type and communication method must be clearly defined.
Clearly define the flange standards for process pipelines, such as GB national standards, JB mechanical industry standards, HG chemical industry standards, SH petrochemical standards, as well as JIS Japanese standards and ANSI American standards. Matching flanges to the corresponding standards are essential for easy installation.
When selecting a flow meter, the requirements for straight pipe sections, the rational layout of the process pipeline, and the installation method should be considered comprehensively. For example: the condition of the upstream and downstream straight pipe sections, whether there are elbows, expansion joints, tees, pumps, valves, etc.; understand the type of valve and whether it is used for flow regulation; whether the installation method is horizontal, vertical, fixed, or mobile; whether there is bidirectional flow and the frequency and pattern of flow direction changes; under the same principle and type of flow meter, generally, the more channels, the higher the measurement accuracy, and the shorter the required straight pipe section.
Power supply requirements. On-site power supply (AC or DC, battery), voltage range, controller interface requirements (number of wires, etc.).
