What should the mass flow controller pay attention to

What should the mass flow controller pay attention to? The mass flow controller adopts a dot-matrix liquid crystal display with backlight and wide temperature. It has many functions and is applicable. The mass flow controller does not need to be preheated and has the remarkable characteristics of instant start, so that the mass flow controller can be turned on to control the flow of the vacuum coating step system in just one second, and measure and detect mass flow, volume flow, pressure and temperature parameters in real time. The flow parameters will be fully filled with temperature and pressure. The gas module program is directly displayed on the screen of the mass flow controller, and the gas type can be switched directly through the screen button operation. The mass flow controller can be used for both gas flow measurement and process control. The mass flow controller is produced by introducing foreign technology, without temperature and pressure compensation, and can directly measure the mass flow of the fluid. The outstanding features of mass flow controllers are: no moving parts; small pressure loss; wide range ratio; high precision; high reliability; simple installation and convenient operation. When using mass flow controllers for operations, combined with our mass flow controller experience and test conditions, there are several aspects that we should pay attention to: When the working conditions of the instrument change, the zero position of the instrument should be readjusted . At the same time, the conduit of the instrument must be installed horizontally and calibrated with a level. Otherwise, the influence of the change of working conditions on the zero drift will be increased. The frame should not vibrate or sway, so it is not suitable for use on ships. A large number of test data within the flow range are correlated, and the linear regression equation is calculated using the principle of the least square method. The correlation coefficientλThe values ​​are all in the range of 0.999 to 0.9999, which proves that the instrument has good linearity. However, there is a difference between linearity and range, the greater the flow rate, the more serious the nonlinearity, so the range is generally limited to 0-4 standard liters per hour to ensure good linearity. In order to measure a large flow rate while ensuring linearity, the mass flow controller can use the shunt principle to expand the measuring range of the instrument. If the bypass tube, Venturi tube, orifice plate are used together, the measuring range can be expanded to tens, hundreds, thousands of standard liters per hour, up to tens of thousands of standard cubic meters. Although the specific heat of a real gas varies with the pressure, and even some gases have relatively large fluctuations, the measurement accuracy of the mass flow controller can still be maintained within a certain range. In the selection of conduit material, in addition to considering corrosion resistance, it is better to choose materials with better thermal conductivity. As mass flow controllers and other instruments must work normally when the specific heat of the gas is relatively stable, the specific heat value is very low when the gas composition is unstable, there is fog in the center of the gas, and the working conditions are close to the critical area of ​​liquefaction of the gas. Unstable, should not use this instrument.