#SRI-8690-2007

SRI GC DETECTORS-CCD-CATALYTIC CONDUCTIVITY DETECTOR

• Detects down to 500ppm
• Hydrocarbon and hydrogen selective
• Gasless operating capability - runs on air!
• Inexpensive and rugged with a built-in spare

The CCD is about as sensitive as a TCD detector but has the hydrocarbon selectivity of an FID while operating on air alone. The CCD needs no high pressure cylinder gases such as hydrogen or helium to operate, just ambient air, so it lends itself to use in SRI's unique Gas-less GCs where a built-in air compressor supplies the carrier gas. The CCD can also be used as a hydrocarbon monitor in non-chromatographic applications where the CCD senses the total hydrocarbon content of a flowing air stream, or as a hydrogen/hydrocarbon leak detector.

The Catalytic Combustion Detector (CCD) consists of a tiny coil of platinum wire embedded in a catalytic ceramic bead. A small electric current flows through the platinum coil heating the ceramic bead to about 500°C. The CCD is maintained in an oxidative environment typically by using air as the carrier gas. When hydrogen or a hydrocarbon molecule impacts the hot bead it combusts on the surface raising the temperature and resistance of the platinum wire. The resistance change causes the detector output signal to change thus producing a peak.

The CCD detector bead is very rugged and can be expected to last a long time. A second bead is included in the detector housing at no extra cost thus providing a built-in replacement in the event the first bead becomes inoperable. Replacement bead sets install in minutes with no tools and are very economical, making this detector a good choice for academic settings where detectors may be damaged by inexperienced operators. The brass detector housing is mounted on a stainless steel bulkhead fitting which is secured directly to the wall of the GC column oven.