Although the physical concept of the sensor is simple, there are various considerations to make the measurement precise
and reliable. For instance, errors due to non-laminar gas flow, in particular at the inner and outer orifices lead to non-linear effects, which should be taken into account. The effect of temperature is also important in the sensing process and
should be excluded.
In an MFC, in addition to a sensor, some controlling systems exist to regulate the gas flow rate. At the center of this system, there is a precise solenoid valve which is capable of adjusting the inlet aperture so that the flow of the gas is equivalent to the flow set by the user.
In IRASOL MFCs, we employ specific technologies which make the exact and repeatable adjustment in the valve. The
gas flow control circuit instructs the solenoid valve to regulate its opening in order that the gas flow becomes equal to
the set flow.
Function diagram of the device is illustrated in Figure 2. The control circuit is connected to the LCD and control keys and
reads the pressure and temperature values of the sensors and orders to the solenoid valve.
The calculated or regulated flow is displayed on the monitor and in addition, the control circuit can be used to display
and transfer of the data from/to a computer. By means of a user interface, it is possible to identify all the connected MFCs
automatically and control them simultaneously using a flow pattern adjusted by the user.