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Flowmeter accuracy factory parameters introduction

The flowmeter must be verified according to the verification procedure before leaving the factory. Some types of flowmeters, such as vortex flowmeters, electromagnetic flowmeters, turbine flowmeters, Coriolis mass flowmeters, etc., must also pass the calibration fluid in the flow standard device to perform calibration on a checklist. Calibration is sometimes referred to as calibrating the scale. However, after the factory-qualified flowmeter is installed at the use site, it usually has to pass the practice test of the use link to be truly “qualified”. This link is the on-site verification of the accuracy of the flowmeter indication during the acceptance check. This work is called "validation" because it is different from the verification. The term “certification” is defined in the national standard as “a procedure for ascertaining or confirming the compliance of a measuring instrument with statutory requirements, which includes inspection, marking and/or issuing a certificate of verification” [4]. Obviously, for a flow meter, the verification is the work performed on an appliance. When a flowmeter is installed at the use site, it is often matched with other related instruments (such as a secondary meter), together with the measured object to form a flow measurement system, and operate in a specific use environment. Each measuring instrument included in a flow measuring system may be all qualified, but it may not be qualified to form a flow measuring system because the appliance is improperly selected, the range is not properly selected, the matching between the appliances is not suitable, and the installation is unreasonable. If the environment is so bad that the appliance cannot be adapted, and the measurement object is too high for the measuring range of the appliance, the system error will be too large. Therefore, the verification described here is for a measurement system that operates in a specific environment for a specific object. A flow meter may not be "qualified" in a particular environment, and an environment may be "qualified." Services that cover an object may not be "qualified", and may be "qualified" as another object service. Therefore, verification cannot be separated from specific systems, specific objects, and specific environments.
The term “alignment” is defined in the “Metrics Dictionary” as “comparing the magnitudes of similar benchmarks, standards, or work measuring instruments of the same accuracy level under specified conditions” [5]. It seems that it is not entirely appropriate to use the comparison to represent the on-site verification work, because some of the on-site verifications are compared between measurement systems of the same accuracy level, while others are not. The term “verification” is defined in GBlT 6583 1 994 as “approved classes that pass the inspection and provide objective evidence that the specified requirements have been met.” 6 Although this is a term in quality management and quality assurance standards, it is borrowed from the measurement system. The quality management is basically also used together.
But no matter what the name is, this work must be done, and it is a very important thing. At the time of verification, the supplier may put forward a lot of data and reasons to prove that the measurement system is accurate enough, and the owner unit accepts the inspection; it may also be the installation and commissioning unit to deliver the work, and the construction unit or the supervision unit appointed by the construction unit to accept; In the same unit, it may be the metering equipment department, and the inspection department will accept it.

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