Agilent Technologies 5975C TAD VL MSD Troubleshooting And Maintenance Manual page 62

3
CI Troubleshooting
3
4
Do not loosen the nuts on any VCR fittings unless you intend to replace the gaskets.
CA UT IO N
Otherwise, you will create an air leak.
5
6
If you use argon or other introduced gas to find air leaks, this does not work
well for the reagent gas flow system. It takes as long as 15 minutes for the peak
to reach the ion source if the leak is at the inlet to the flow module.
62
•
If you just replaced the reagent gas bottle or gas purifier, check the
fittings you just opened and refastened.
Check for tightness of seals at GC inlet and interface column nuts. Ferrules
for capillary columns often loosen after several heat cycles. Do not
overtighten the interface nut.
If any of the fittings inside the flow module (VCR fittings) were loosened
and then retightened, the gasket must be replaced. These gaskets are good
for one use only.
Remember that most small air leaks visible in CI mode are located in either
the carrier gas or reagent gas flow paths. Leaks into the analyzer chamber
are not likely to be seen in CI because of the higher pressure inside the
ionization chamber.
Half-split the system.
•
Close valves starting at the gas select valves (Gas A , then Gas B), then
close the shutoff valve. See
•
Cool and vent the MSD, remove the GC column, and cap off the interface.
Figure 3 and
5975 Series MSD Troubleshooting and Maintenance Manual
Table 6.