Forward injector pressure regulation

Figure 2.47 Injector forward pressure regulation. 1. Carrier gas inlet filter, 2. proportional control valve, 3. electronic pressure sensor, 4. septum purge on/off valve, 5.

The adaptation of external devices such as headspace, P T or thermal desorption is straightforward, with the pressure sensor installed close to the injector head which is generally the case with commercial forward-regulated GC instruments. If the pressure sensor is installed in the split line of the injector, it has to be moved close to the inlet to provide a short carrier gas regulation loop. Carrier gas flow and pressure in the external device is controlled by the EPC module of the GC. The position of the pressure sensor in the flow path of an inlet is important for accurate measurement of the inlet pressure to get rapid feedback control. 

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