BUCHI DuMaster D-480 - Manual (Page 172)

Operation Manual D-480 ©BÜCH Labortechnik AG
8 - Maintaining the instrument 172
Safety instruction
Strictly observe the safety instruction "Gas pressure" under Warning notes during operation (on
page 24).
"Preparing the instrument: Gas pressure"
Proceed as follows:
 Shut off gas supply. Open the "Replace part" dialog in the operating software by selecting
Options > Maintenance > Replace Part.
 Wait for pressure drop without pressing any buttons until the message "Part can now be
replaced." is displayed and the Finish button becomes accessible.
 Pressure has been reduced when the following displays show "0" on screen:
 "MFC CO2".
 "Flow CO2".
 "Pressure".
 The instrument is now ready for replacement of the part.
Follow-up instrument preparation: Gas pressure / gas-tightness
Proceed as follows:
 Close the "Replace part" dialog in the operating software. To do so, click Finish in the "Replace
part" dialog. This automatically switches on the gas again and the atmospheric nitrogen is
removed by flushing with CO
2
.
 Decide:
If...
 ... approximately the same flow and pressure values as prior to maintenance work are
displayed: The instrument is ready to measure again.
 ... distinctly different flow and pressure values to those displayed prior to maintenance work
are displayed: Perform a leak test. See Performing a leak test (on page 242). The
instrument is only ready to measure when the leak test is successful.
Conditioning newly installed tubes
Purpose of conditioning
Newly installed tubes must be conditioned:
 to remove nitrogen from air inclusions in the filling material.
 to remove moisture from the tube fillings.
 to remove contaminations.
Without conditioning, analysis results would be distorted.
Types of conditioning
There are the following types of conditioning new tubes:
 Flushing tubes to remove nitrogen from air inclusions in the filling material. The following are
flushed:
 Large drying tube.
 Small drying tube.