Use the following procedure to evaluate the performance of your RTGA interface if you think there might be a leak or plug:

1) First, check the interface pressure displayed on the PDR2000*. With the interface exposed to ambient pressure (room air), the pressure should be in the range of ~80-120 mTorr (0.080 to 0.120 Torr). If the pressure is significantly higher than this, then you may have a leak in one of the interface fittings. If the pressure is significantly lower than this, then your sample orifice may be plugged. Proceed to the next steps to isolate and identify the problem.

*The capacitance manometer should be on for at least 4 hours before evaluating the pressure.

2) To check for leaks in the 5975 MSD, close the isolation valve on the RTGA interface, and then check the pressure on the front panel display on the MSD – press the “Menu” key until “MS parameters” is displayed and the “Item” key until “High Vacuum Pressure” is displayed. With the isolation valve closed and the 5975 MSD pumped down, the High Vacuum Pressure should be in the mid to low 10^-7 Torr range. If the pressure is significantly higher than this, then you may have a leak in the MSD or in the interface connection to the vacuum manifold.

To confirm a leak in the 5975 MSD, run an “Air and Water Check” from the 5975 Tune Window – make sure the isolation valve is closed and select “Air and Water Check” from the “Tune” menu of the 5975 Tune Window. Select “Yes” to adjust to standard values. At the bottom of the 597x Air and Water Check report, the 28/69 Nitrogen% should be <10%. If the Nitrogen% is significantly higher than 10%, then you may have a leak in the MSD.

3) To check for a leak in the RTGA interface, close the isolation valve, and plug both arms of the sample interface “Tee” with the 1/16″ caps provided in the RTGA ship kit. If your interface is configured without a tee, then plug the inlet with an appropriate fitting. Wait for the interface pressure on the PDR2000 to stabilize, which may take several minutes. With the isolation valve closed and the interface plugged, the interface pressure should be close to 0 Torr. If the pressure stabilizes significantly higher than 0 Torr, then you may have a leak in the interface.

To confirm a leak in the RTGA interface, run an “Air and Water Check” as described in step 2 with the isolation valve *open* and the sample inlet plugged. At the bottom of the 597x Air and Water Check report, the 28/69 Nitrogen% should be <10%. If the Nitrogen% is significantly higher than 10% then you may have a leak in one of the fittings connected to the RTGA interface.

4) To check for a plugged sample orifice, open one arm of the sample interface “Tee” to ambient (room) air. If the interface pressure displayed on the PDR2000 is significantly below 80 mTorr (0.08 Torr), then your sample orifice may be plugged.

To confirm a plugged sample orifice, with the isolation valve *open* and the sample interface tee open to ambient (room) air, run an “Air and Water Check” as described in step 2. At the bottom of the 597x Air and Water Check report, the 28/69 Nitrogen% should be >80%. If the Nitrogen% is significantly lower than 80% then you probably have a plugged sample orifice.