Metrohm 840 PC Control 5.0 / Touch Control - Manual (Page 218)

4.1 Titrations
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PC Control / Touch Control
4.1.2 Endpoint titrations (SET)
Under Start conditions the parameters for the start volume of titrant
and for the measurement of the initial measured value are edited:
• Pause 1 (d): Waiting time, e. g. for electrode equilibration, before a
start volume is added.
• Start volume (d): Volume which is added before the start of the ti-
tration. Under Dosing rate (d) you can enter the rate at which the
start volume is added.
• Pause 2 (d): Waiting time which is allowed to elapse before the start
of the titration after the start volume has been added.
Parameters for the Initial measured value:
• Signal drift (d): Drift, i.e. alteration in the measured value per
minute, which has to be reached before the measured value will be
accepted.
• Waiting time min. (d): The measured value is not accepted until
the minimum waiting time has elapsed, even if the measured value
drift has already been reached. The minimum waiting time is only
important for drift-controlled measurements.
• Waiting time max. (d): If the signal drift is switched off or has not
yet been reached then the measured value will be accepted after
the maximum waiting time has elapsed.
Editing the Control parameters for endpoint 1 and endpoint 2:
• EP1 at (d): Measured value for the first endpoint.
• Titration rate (d): Three predefined sets of parameters can be
selected for the titration rate (see Table on following page). If indi-
vidual titration parameters need to be adapted you should select
the setting User and edit the individual titration parameters under
User-defined Parameters .
Editing the User-defined Parameters:
• Dynamics (d): The dynamics defines the measured value range
(control range) before the preset endpoint. In the control range dos-
ing is controlled by the Minimum rate. The closer the endpoint, the
slower the dosing until the Minimum rate has been reached. The
larger the control range, the slower the titration. Outside the control
range dosing is carried out continuously at the Maximum rate.
• Maximum rate (d): Rate at which dosing is carried out outside the
control range. The maximum dosing rate depends on the cylinder
volume of the exchange or dosing unit used (see Section 3.8.6).
• Minimum rate (d): This parameter determines the dosing rate right
at the start of the titration and in the Dynamic range at the end of the
titration. It has a decisive influence on the titration rate and therefore
on the accuracy. The smaller the selected minimum rate, the slower
the titration.