Basic HTML Version
Appendix B
5/20/2009
33
open the in-line valve and increase the oxygen gas pressure
to 5 psig. [HIT RETURN WHEN DONE].
17.4.7.7.Wait one minute. A tone will sound. A clock on the screen
counts down the time. When the tone sounds, the screen
displays the message “I’m finished purging the oxygen
scrubber. [HIT RETURN TO ACKNOWLEDGE]
17.4.7.8.Tighten the top nut on the oxygen scrubber. Increase the
pressure to normal. [HIT RETURN WHEN DONE]
17.4.7.9.The instrument should be conditioned after replacing the
oxygen scrubber by running two blanks before proceeding to
a sample run.
17.4.7.10.
The procedure for replacing the oxygen scrubber is
identical to that of the helium scrubber. The only difference
is the omission of the 5 minute purge.
17.4.8.
Carbon Dioxide Trap Replacement
17.4.8.1.Replace the carbon dioxide trap. Tighten the lower nut only.
[HIT RETURN WHEN DONE]
17.4.8.2.Be sure to orient the trap correctly, with the Ascarite portion
toward the top.
17.4.8.3.Check the o-rings and re-grease lightly, also check the
effluent filters at this time.
17.4.8.4.Wait 1 minute. A tone will sound. A clock counts down the
time on the screen and then displays “I’m finished purging
the carbon dioxide trap”. [HIT RETURN TO
ACKNOWLEDGE]
17.4.8.5.Tighten the top nut on the carbon dioxide trap. Increase the
pressure to normal. [HIT RETURN WHEN DONE] (Ignore
the instructions regarding pressure).
17.4.8.6.When completed, the Tube Replacement Menu for the CHN
analysis mode will be displayed.
17.5.
Important Factors for Proper 440 Operation
17.5.1.
Pack the scrubber tubes loosely.
17.5.2.
Vibrate or tap down the combustion tube packing chemicals while
packing to assure a fairly tight tube. DO NOT over-tighten.
17.5.3.
Oxygen pressure should be at ≈ 20 psig.
17.5.4.
Helium pressure should be at ≈ 18 psig and the fill time (FT) for a
run should be between 20 and 40 seconds.
17.5.5.
When greasing o-rings or gaskets, it is recommended to use Krytox
(R) by Dupont.
17.5.6.
The furnace temperatures reach set temperature very quickly. Do
not set the furnaces to anything but the temperature for analysis.
17.5.7.
Never set the combustion temperature above 1100 °C.
17.5.8.
Never set the reduction temperature above 900 °C.
17.5.9.
All valves are “Normally Closed” type.