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『Verification Regulations for Ultrasonic Flowmeters』Related information(flow rotameter|digital flow meter|balo meter|hydraulic flow meter|volumetric meter|positive displacement meter|pitot tube flow meter|displacement meter|cfm meter|variable area flow meter|inline flow meter|differential pressure flow meter|calibrated flow meter|velocity meter|paddle wheel flow meter|oval gear flow meter|anemometer hvac|multiphase flow meter|doppler flow meter|thorpe tube flowmeter|heat flow meter)
What is the allowable error range of ultrasonic flowmeter?
The theoretical error of gas ultrasonic flowmeter can reach over 0.3%, but due to the limitations of domestic calibration devices, the working level accuracy is mostly 0.25%. According to JJG1030-2007 Ultrasonic flowmeter calibration regulations, the error between the tested meter and the standard meter cannot be less than three times.. That is to say, a standard positive coarse gauge of 0.25 can only verify a gauge of 0.75 level at most. Therefore, currently domestic testing institutions can only issue Level 1 certificates at most. When you are designing, as long as the manufacturer issues a Level 1 certificate, you can clear the documents.
2. The relationship between the minimum flow rate and the range ratio of 1:400 for ultrasonic flow meters
The core conclusion of the relationship between the minimum flow rate and the range ratio of 1:400 for ultrasonic flow meters is that the range ratio of 1:400 means that the minimum measurable flow rate is 1/400 of the full-scale flow rate, which directly reflects the lower limit and sensitivity of the instruments measurement range.
. 1. Rangeability is defined as the ratio of maximum flow rate to minimum flow rate. 1: 400 indicates that the minimum measurable flow_600x400.jpg)
2. Factors affecting minimum flow rate • Sensor sensitivity: High frequency ultrasonic probes (usually above 1MHz) can detect lower flow rate signals. Signal processing algorithm: using FFT or cross-correlation algorithm to enhance small signal recognition ability. Pipeline conditions: The length of the straight pipe section should be ≥ 10D (D is the pipe diameter) to ensure a stable flow field. three Technical Implementation Key Parameters | Parameter Items | Typical Requirements | | -------------------------------------------------------------------------------------------------------- Selection precautions: The actual minimum flow rate should be greater than the nominal minimum flow rate of the instrument by 20% to avoid measurement distortion. When the gas content of the medium is greater than 5%, a Doppler ultrasonic flowmeter should be selected. The installation position should avoid distances above 3D (where D represents the pipe diameter) of the pump valve. Data basis: JJG 1030-2022 "Ultrasonic Flow Meter Calibration Regulations" and Emerson 2023 Flow Meter Technical Manual.