BUCHI DuMaster D-480 - Manual (Page 173)

Operation Manual D-480 ©BÜCH Labortechnik AG
8 - Maintaining the instrument 173
 Baking out tubes to remove moisture and contaminations from the tube fillings. The following are
baked out:
 Combustion tube.
 Reduction tube.
 Post combustion tube.
Flushing tubes
Requirements:
 A new tube has been installed.
 The analyzer is in "Replace part" status.
 The tube ends are closed.
Safety instruction
Strictly observe the safety instruction "Gas pressure" under Warning notes during operation (on
page 24).
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 carrier gas for five minutes.
 Decide:
If the operating software status view displays...
 ... approximately the same flow and pressure values as prior to maintenance work are
displayed: The instrument is ready to measure again. Go to the next step.
 ... 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). Only move
on to the next step once the leak test is successful.
 Performing blank value determinations. See Determining blank values (on page 144). Allocate
the method "Blank with O2" to the samples.
 Only stop blank value determination when the N blank value is stable and small. See "Measure of
gas-tightness" in Types of blank value determination and their settings (on page 143). The
instrument is then ready to measure again.
Conditioning combustion, post combustion and reduction tube
The following tables explains conditioning rules for the various modes:
Mode Reaction tube Conditioning rule
N
 Combustion tube
 Post combustion tube
 Reduction tube
Bake out at working temperature for 15 minutes.
Baking out combustion, post combustion and reduction tube
Requirements:
 A new combustion tube and/or reduction tube has been installed.
 The analyzer is in "Replace part" status.
 The tube ends must be open. For this,...
 ... the quartz glass bridge must not be attached to the end of the combustion tube.
 ... the ground joint is not clipped onto the end of the reduction tube.
 ... the ground joint must not be clipped onto the end of the post combustion tube.