Metrohm 894 Professional CVS - Manual (Page 39)

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3 Installation
894 Professional CVS
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Sealing unused PTFE capillaries of the fourfold micro dos-
ing tip
To prevent accidental aspiration of solution from the measuring vessel,
unused PTFE capillaries must be sealed. Proceed as follows:
1 Screw a coupling (6.1808.000) to each unused PTFE capillary.
2 Screw a threaded stopper (6.1446.040) to each coupling
(6.1808.000).
6.1808.000 6.1446.040
Figure 21 Sealing the PTFE capillary of a fourfold micro dosing tip
3.3.2 Installing capillaries
You can add the samples from a Sample Processor in an automated way
by using capillaries. The capillaries are connected to the peristaltic pump
installed on the Sample Processor and/or a dosing unit (see figures in
Chapter 5.3.2, page 64). Several pressure screws (e.g. 6.2744.010) are
required to attach the capillaries.
In order to obtain optimum analysis results, the capillary connections have
to be as tight as possible and free of dead volume. Dead volume occurs if
two capillary ends connected to each other do not fit exactly, thus allow-
ing liquid to escape. There are two possible causes for this:
￭ The capillary ends do not have exactly flat edges.
￭ The two capillary ends do not completely meet.
We recommend using the capillary cutter (6.2621.080) to obtain exactly
flat edges of capillaries.
Installing the capillary in the RDE measuring head
We recommend using a PEEK capillary (e.g. 6.1831.020) in the measuring
head. Proceed as follows: