BUCHI DuMaster D-480 - Manual (Page 179)

Operation Manual D-480 ©BÜCH Labortechnik AG
8 - Maintaining the instrument 179
 Set oxygen dosing parameters (method) for conditioning and calibration samples according to
the following list:
Weight 2 - 20 mg:
 O
2
dosing time 110 sec.
 O
2
flow = 50 ml/min.
 O
2
cut-off threshold = 30 %.
Weight 20 - 100 mg:
 O
2
dosing time 110 sec.
 O
2
flow = 100 ml/min.
 O
2
cut-off threshold = 30 %.
Weight 100 - 200 mg:
 O
2
dosing time 120 sec.
 O
2
flow = 150 ml/min.
 O
2
cut-off threshold = 30 %.
Weight 200 - 300 mg:
 O
2
dosing time 120 sec.
 O
2
flow = 200 ml/min.
 O
2
cut-off threshold = 30 %.
Weight 300 - 400 mg:
 O
2
dosing time 120 sec.
 O
2
flow = 250 ml/min.
 O
2
cut-off threshold = 30 %.
Weight 400 - 500 mg:
 O
2
dosing time 120 sec.
 O
2
flow = 300 ml/min.
 O
2
cut-off threshold = 30 %.
 Start the analysis process by selecting System > Auto run.
 Check whether the field "MFC O2" on the screen displays the expected setpoint value during the
combustion time. See Values for oxygen dosing (on page 137).
 Observe the measuring results. If the N blank value is not below 50 after stabilization: Stop
continuous analysis via System > Single. Find out the reason of the increased blank value and
correct it. Cf. Types of blank value determination and their settings (on page 143).
 Save the original values. See Data backup and printing (on page 158).
Phase 2: Ascertaining appropriate calculation methods
Proceed as follows:
 Execute the following command: Math. > Calibration. If sequential blank value determination is
activated a message window opens showing the corresponding information.
 Click Yes to continue. The "Configure calibration" dialog appears.
 Define the following settings:
 Check the box next to "Two calibration ranges".
 Enter 1 as the polynomial degree for the lower and upper range. This corresponds to linear
calculation.