Advantages of Combining Flow and Pressure Control
In a number of applications, both pressure and flow control play an important role in achieving system performance. One typical example of such an application is split/splitless injectors in gas chromatography (GC).
In gas chromatography, the choice between maintaining constant flow and maintaining constant pressure depends on a multitude of factors such as analytic type, sampling method and detector type. When maintaining pressure constant, flow rate can decline with increasing column temperature. This can lead to incompatibility issues with certain detector types, e.g. mass spectrometers and thermal conductivity detectors. When maintaining flow constant, higher pressures may need to be used, and this may fall out of the range of certain instruments.
Read Axetris’ application note on gas chromatography applications.
Keeping the many advantages and disadvantages of flow and pressure control in mind, one possible solution is to combine both. Axetris mass flow meters and controllers can be easily combined with pressure sensors to build compact and fast-reacting flow+pressure controllers. Due to the quick reaction time achievable with the Axetris MEMS-based thermal mass flow technology, they lend themselves to easy integration as the controlling element in a pressure control loop. Axetris application experts help OEMs worldwide optimally combine flow and pressure control to achieve maximum performance.