CAST is a stand alone soot generating unit. In autonomous mode it works with its internal flow controller and allows the generation of soot particle with high accuracy, excellent stability and repeatability. Nevertherless there are applications that need better flow control, e.g. mass flow control, in order to arrive higher precision and reproducibility. Some models of miniCAST series 5200 are equiped with gas connectors for external flow control.
Following image shows the mass flow control unit PMF-52 from JING