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What are the verification methods for mass flowmeters - focus on microfluidic control technology

Mass flowmeters are generally used only for the measurement of liquid flow. Verification of it is usually done in the laboratory (flow standard equipment) and its specific conditions. This is what we commonly call offline verification. We know that the purpose of the mass flow meter verification is to determine the metering performance of the meter when it is actually used. Laboratory verification has the following problems:

1 The verification medium is different from the actual measured medium, and its physical properties are different.
2 The test conditions such as temperature and pressure are inconsistent with the application conditions of the flowmeter;
3 The flow meter installation pattern is also very different from the site.

The above description shows that the verification or performance evaluation of the mass flow meter in the laboratory is different from the actual performance of the flow meter, which is far from the goal of accurate measurement. For example, when mass flow meters are used in custody transfer measurement, this difference is likely to be the source of disputes between buyers and sellers and must be eliminated.

Under the current technical conditions, it is very difficult to correct the verification conditions of the flowmeter to the application conditions. Typical, such as viscosity correction, there is no corrective method, let alone some unpredictable factors (such as installation, flow state Corrections, etc.) Therefore, the best way to solve this problem is to perform on-line verification of the mass flowmeter.

The on-line verification of the mass flow meter is a kind of real-liquid verification. Compared with the laboratory verification, it has many special characteristics or requirements. The main points are summed up as follows:

(1) There must be a fixed or movable flow standard device for the verification of mass flowmeters. In addition to the accuracy of the device, the device's operating temperature range, pressure rating, and media compatibility must also meet the online verification requirements. If it is a mobile traffic standard, the device is also required to be light and flexible;
(2) During the verification process, the fluid must be in a confined state to ensure that the verification conditions do not change, but also to ensure the safety of the verification site;
(3) It is not allowed to interrupt the fluid during the verification process;
(4) If the flow meter to be inspected is tested with a moving standard device, the flow meter shall have a corresponding interface, valves, and supporting recovery cleaning facilities, site, and power supply.

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