Tube Replacement for the SCD
The Burner has two combustion tubes that require replacement: the upper ceramic tube and the Large Ceramic Tube. Generally the tubes should be replaced only if sensitivity decreases. The “Troubleshooting” chapter provides additional information to assist in determining whether tube replacement may be necessary. Refer to Figure 1 on page 26 for proper part nomenclature. Follow the instructions below for tube replacement.
1Turn off power to the GC and the Controller and let the system cool down under vacuum.
2Turn off power to the vacuum pump.
3Lift the Burner out of the shroud. It is recommended to remove the coil, noting the position of the ferrule. In some instances, if the coil can be uncoiled, it may be convenient to leave it attached to the Burner.
4Disconnect the hydrogen and oxidant lines.
5Disconnect the power connector that leads to the GC, if necessary.
6Tilt the Burner at an angle, so that when loosening the union fitting the upper ceramic tube does not slide down into the large ceramic tube.
7Loosen and disconnect the union fitting, and pull the splitter fitting and upper ceramic tube out of the Burner.
8Slide the upper ceramic tube out of the splitter fitting.
9Slide the upper ceramic tube into the splitter fitting, so that approximately 4 mm of the tube extends beyond the top of the fitting. Then, slide the double taper ferrule onto the tube (see Figure 37 and Figure 38 for proper positioning). Gently holding these parts so that neither the ferrule nor the upper ceramic tube slip out of position,
Figure 37 Orientation of the Double Taper Ferrule
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