8. Technical notes for the product performance
8.1 Measurement principle
The products utilize the Company’s proprietary micro-machined
(MEMS) calorimetric sensing and data process technology. A thermal
signal generator with a pair of sensing elements at the up and
downstream of the microheater is precisely manufactured and
separated at predefined micrometer distances on a chip surface with
excellent thermal isolation. When a fluid is flowing through the sensing
chip, the fluid carries the thermal signal downstream. The sensing
elements register the temperature differences, further correlated to
the fluid mass flow rate via the calibration process.
The calorimetric sensing approach offers a large dynamic range with a
better performance against the environmental parameter alternations.
Please refer to the company's US patents and other publications made available to the public for
additional information.
8.2 Precautions for the best performance of the product
8.2.1. Comparison with a third party reference meter
It is very common that a user may compare the data from the product with a third-party reference
meter, and in many cases, there could be some discrepancies.
When performing such a comparison, please note that the reference meter should have a better-
specified accuracy (about 1/3 of the product), and pay special attention to the differences in the
reading accuracy and full-scale accuracy.
A full scale accuracy = reading accuracy x (full scale flow rate/ set point (current) flow rate)
Another key point to compare the different flow meter is that as long as the fluidic flow is a
continuous flow without pulsation, then the fluidic dynamic will have the system following the
Bernoulli equation:
where ρ is the fluid density; g is the acceleration due to gravity; P1 is the pressure of the reference
meter; P2 is the pressure at the test meter; v1 is the velocity of the reference meter, and v2 is the
velocity of the test meter. h1 and h2 are the corresponding height for the meters which in most cases
is the same in the system. Therefore, it would be very critical to have the system does not have a
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