Gas Chromatography Detectors - The Flame Ionization detector > The Design of the FID > Page 37


The Design of the FID

A detector is considered to be composed of a sensor and associated electronics and it is the sensor unit that is commonly referred to as the FID. A diagram of the FID sensor is shown in figure 16. The body and the cylindrical electrode are usually made of stainless steel and stainless steel fittings connect the detector to the appropriate gas supplies. The jet and the electrodes are insulated from the main body of the sensor with appropriate high temperature insulators. Care must be taken in selecting these insulators as many glasses (with the exception of fused quartz) and some ceramic materials become conducting at high temperatures (200-300oC) [14].


Figure 16. The FID Sensor