What are the calibration procedures for flow meters?

『Flow meter calibration』Related information(clamp on meter|electromagnetic meter|venturi meterrotameter|orifice meter|ultrasonic flow meter|mass flow meter|coriolis mass flow meter|coriolis flow meter|magnetic flow meter|magmeter flow meter|magflow flow meter|mag meter flow meter|electromagnetic flow meter|vortex flow meter|turbine flow meter|thermal mass flow meter|thermal flow meter|rotameter flow meter)

1. JJG 640-2016 Calibration Regulations for Differential Pressure Flowmeters JJG 640-2016 "Calibration Regulations for Differential Pressure Flowmeters" was officially implemented on May 30, 2017, replacing the 1994 version. Its core lies in the addition of indication error detection and disturbance accompanying measurement method, and the improvement of technical specifications for five accuracy levels from 0.5 to 2.5. 1. Scope of application: Applicable to the initial calibration, subsequent calibration, and in-service inspection of standard throttling components and differential pressure devices for integrated differential pressure flow meters and split differential pressure flow meters.

2. Main technical updates: According to GB 2624-2006, technical parameters such as diameter ratio and uncertainty of outflow coefficient of standard throttling components have been adjusted, and certificate internal page format specifications for three calibration methods have been added.

3. Metrological performance core refers to the slow beam stupid standard. 3.1 Geometric detection method: applicable to standard throttling components, with outflow coefficient C as the core parameter and uncertainty requirements of 0.5% -2.0%.

3.2 Coefficient detection method: applicable to differential pressure devices, with flow coefficient alpha as the core parameter and uncertainty requirements.

Requirement is ± 0.5% - ± 2.5%

3.3 Indication error method: applicable to the entire system, the core parameter is flow indication, and its uncertainty requirement is ± 0.5% - ± 2.5%

4. Key technical requirements for standard throttling components 4.1 Standard orifice plate: upstream end face flatness requirement hA<0

.0025 (D-D); Edge arc radius rk ≤ 0.0004d

4.2 ISA 1932 nozzle: throat diameter deviation ≤± 0.05% average value; Surface roughness Ra ≤ 10-4d

5. Key points for verification implementation: Differential pressure transmitters should be equipped with at least 2 units of different ranges; Each traffic point is detected at least 3 times; The verification flow point should include 5 characteristic points such as Qmax and 0.75Qmax; The fluid needs to circulate thoroughly for at least 10 minutes to eliminate bubbles. For the classic Venturi tube, it is recommended to prioritize the use of a mechanically processed contraction section (with an uncertainty of 1%); When D<200mm, special attention should be paid to the tolerance of ≤ 0.2mm when detecting the thickness E of the orifice plate; High precision calibration (level 0.5) requires controlling environmental temperature fluctuations to be ≤ ± 2 ℃.

2. Verification Regulations for Differential Pressure Flowmeters hj640-2016

Core Conclusion: JJG 640-2016 "Verification Regulations for Differential Pressure Flowmeters" is an authoritative technical specification for the metrological performance of differential pressure flow meters in China, applicable to initial verification, subsequent verification, and inspection during use.

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