Advanced gas mass flow controller work test report

Release time：

09 Jun,2022

Summary

MFC controls gas flow based on the operation of a flow meter and proportional valve under a PID control algorithm. The PID algorithm used by MFC generally has a dynamic adjustment function, dynamically adjusting according to different operating conditions to achieve rapid flow switching (generally response time <1s) and stable output of the set flow.

Advanced gas mass flow controller work test report

MFC Stable Flow Control Technology: MFC Gas flow control is achieved based on the flow meter and proportional valve PID control algorithm. MFC The adopted PID algorithm generally has a dynamic adjustment function, dynamically adjusting according to different operating conditions to achieve fast flow switching (generally response time < 1s ) and stable output of the set flow rate. The following figure shows 10L MFC maximum flow point multi-stability comparison, for example, 10SLM For example, the fluctuation of this product is ± 13sccm , and the three competing products are ± 13sccm , ± 116sccm , ± 19.5sccm。( Data recorded by a third party MFM , the yellow line represents our company's product

Figure 1.2 Three 10L MFC Fluctuation comparison at the full-scale point
Temperature Compensation Technology Research: Temperature compensation ( Temperature compensation) , large temperature changes will have a slight impact on key components such as the internal resistance of the sensor, the density of the gas to be measured, and the gas path structure, which will ultimately lead to 3% reading error (temperature drift error), as shown by the orange line in the figure below. In the design of flow meters and controllers, the full-range temperature method (testing and temperature compensation one by one at different flow rates and temperatures) is used for precise temperature compensation to ensure that the temperature drift error within the full range is controlled within 0.5% or 1% , as shown by the blue line in the figure below.

Figure 1.3 MFC-E 10L Temperature compensation effect test data under flow rate

Thermal capillary principle similar MFC products do not have this temperature compensation production process, and multiple layers of filter screens need to be added to the inlet of the flow path for processing, MEMS Advanced gas flow measurement and control technology has added a temperature compensation process in production, greatly improving product stability and accuracy.

Flow meter pressure drop research: Flow meter pressure drop ( Pressure loss ) is one of the key indicators of the flow meter, which is used to indicate the pressure difference between the input and output ends of the flow meter, and is also the minimum pressure difference to ensure the normal operation of the flow meter. The flow meter pressure drop generally increases with the increase of flow rate, and is also affected by the solution. Based on MEMS (Microelectromechanical Systems), the pressure drop of the flow meter is much smaller than that of vortex flow meters and differential pressure flow meters.

Figure 1.4 Flow meter pressure drop test data

Research on the influence of working pressure on fluctuation: MFC Although changes in pressure at both ends during use will not cause accuracy deviation (mass flow rate is not affected), they will affect the stability of the gas path. When the working pressure increases, MFC fluctuation will increase significantly, as shown in the figure below. When the pressure is 0-0.3MPa , the fluctuation value is less than 0.2% , and in most cases less than 0.1% . When the pressure is greater than 0.4MPa , the fluctuation can reach 0.6% or more. Therefore, MFC it is recommended to control the pressure difference between the front and rear ends within 0.3MPa .

Figure 1.5 MFC-UT 100ml Fluctuation under different working pressures

Using the company's independently developed industrial-grade advanced flow sensor chip, combined with low-pressure loss gas path structure and high-precision digital control circuit and algorithm, high-precision, high-stability, and wide-range ratio control are realized within a wide temperature range. This product is equipped with an on-site debugging screen and an independent power supply interface, perfectly adapting to the semiconductor industry.