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Discussion on operating conditions and performance of several flow meters

The operating conditions or operating conditions of flow meters directly affect their metering performance, and the most direct effect of operating pressure or temperature change on the flow meter is the change of the measurement chamber.

The indirect effect of electromagnetic flowmeter is the change of physical parameters such as viscosity and density of the medium, but the indirect effect can be considered when modifying the physical property. Due to the complexity of flow meter and the discretization of machining assembly, it is almost impossible to use the method of calculation to correct the change of the cavity with the operating condition, and it is impossible to fit the empirical formula to meet the accuracy requirement according to the test data.

Turbine flowmeter for Volumetric flowmeter, in the flow meter type identification, prototype test or quality inspection, natural getter engine was converted into a booster engine, whether the use of exhaust gas turbocharger or mechanical supercharger, turbine flowmeter will encounter the problem of high inlet temperature.

Vortex flowmeter because the compressed air temperature is certainly higher than the uncompressed. Natural suction engine air inlet temperature regardless of the engine in what state there is no big change, whether it is installed in the air flowmeter, or from the throttle valve not far from the intake manifold or wind compartment, are not quite the difference.

For the speed-type turbine flowmeter, the change of operating condition will cause the change of the flow area, which leads to the change of the instrument coefficient. If the operating conditions of the flow meter are the same or close to the actual use, then the off-line verification can satisfy the requirement. However, due to the complexity and variability of operating conditions, off-line verification is often unable to reproduce the actual operating conditions, only online real-flow verification can solve the problem of high accuracy flow measurement, otherwise we should consider additional error.

In a broad sense, the uniformity of the measured medium, the amount of gas (liquid), impurity content and other flow conditions, also belong to the scope of operating conditions of flowmeter, but its impact on the performance of flow meters more complex, and sometimes online real-time verification is difficult to solve.