Servomex NanoTrace DF-760E, Instruction Manual

Page: 134 / 182

130 DF-760E Service
Extreme caution must be used when loosening and tightening the
fittings on the purifier. In particular, care must be taken to avoid
contacting the delicate electrical connections on the side of the
oxygen sensor with the wrenches.
9.3.7.3 Gas Purifier Installation/Replacement Procedure
NOTE
The gas purifier is designed to operate with low ppb (<50 ppb) inlet
gas. Exposure to ambient air can seriously reduce the useful life of
the purifier.
1. Shut off the vacuum source and wait 5 minutes for the pressure to equalize. In
order to minimize the possibility of an ambient intrusion it is critical that the pump
not be running.
2. Using the moisture gas valve control screen (see page 49) start the gas flow through
the zero purifier.
3. Write the installation date on the gas purifier label.
4. Install new gaskets and retainers on the purifier. Gently replace the cap nuts on the
purifier to minimize exposure to ambient air.
5. Open the door and locate the purifier position. See page 21.
6. If installing a new purifier at initial startup, remove the VCR plugs installed in the
plumbing system allowing gas to escape from the lower plug.
7. If replacing a spent purifier, remove the purifier allowing gas to escape from the
lower fitting.
8. Remove both VCR-type cap nuts from the new purifier and quickly install the
purifier
with the arrow pointing up . It may be necessary to slightly spring the
calibration system plumbing to insert the gas purifier. Be sure not to scratch the
gasket surfaces.
9. Screw the fitting nuts at both ends finger-tight allowing gas to escape for two
minutes.
10. Using a backup wrench tighten the nut at the bottom of the purifier 1/4 turn beyond
finger-tight and allow the gas to escape from only the top fitting for an additional
two minutes. Then tighten the top fitting 1/4 turn beyond finger-tight.
11. Continue to allow the gas to flow through the purifier for 24 hours or until the
original analyzer reading is achieved.
After installation is complete, low ppb process gas must be allowed to flow through the gas
purifier to purge ambient gas from the gas lines and valves. Effective purging of the
system can be accomplished by repeatedly opening and closing the valves in the process
and zero legs to start and stop the flow of gas. To automate this purge process see the
purifier purge routine found in the diagnostics menu (see page 68).