Metrohm 930 Compact IC Flex ChS/Deg - Manual (Page 89)

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5 Operation and maintenance
930 Compact IC Flex ChS/Deg (2.930.1260)
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5.12 Servicing the detector
Follow the maintenance instructions in the the detector's manual.
5.13 Rinsing the sample path
Before a new sample is measured, the sample path has to be rinsed with it
long enough to prevent the measuring result from being falsified by the
previous sample (sample carry-over).
The time required to rinse the sample path with the new sample is called
the rinsing time. The rinsing time depends on the transfer time.
The transfer time corresponds to the time the sample needs to flow from
the sample vessel to the end of the sample loop. The transfer time
depends on the following factors:
￭ The pump capacity of the peristaltic pump or Dosino
￭ The total capillary volume
￭ The volume of the gas removed from the sample by the sample degas-
ser
The transfer time can be determined as follows:
Determining the transfer time
1 Emptying the sample path
Pump air through the sample path (pump tubing, tubing connec-
tions, capillary in the degasser, sample loop) for several minutes until
all liquid is displaced by the air.
2 Aspirating the sample and measuring the time
Aspirate a sample typical for the later application and use a stop-
watch to measure the time the sample needs to go from the sample
vessel to the end of the sample loop.
The time upon stopping the watch corresponds to the "transfer
time".
If the sample is injected automatically, the rinsing time has to be at least
three times the transfer time.