Metrohm 840 PC Control 5.0 / Touch Control - Manual (Page 228)

4.1 Titrations
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PC Control / Touch Control
4.1.4 STAT titrations (STAT)
Under Start conditions the parameters for the start volume of titrant
and for the measurement of the initial measured value are edited:
• Pause 1: Waiting time, e. g. for electrode equilibration, before a
start volume is added.
• Start volume: Volume which is added before the start of the titra-
tion. Under Dosing rate you can enter the rate at which the start
volume is added.
• Pause 2: 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: Drift, i.e. alteration in the measured value per min-
ute, which has to be reached before the measured value will be ac-
cepted.
• Waiting time min.: 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 impor-
tant for drift-controlled measurements.
• Waiting time max.: 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 the control point:
• Control point at: Measured value for the control point.
• Titration rate: Three predefined sets of parameters can be se-
lected for the titration rate (see Table on following page). If individ-
ual 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: The dynamics defines the measured value range (control
range) before the preset control point. In the control range dosing is
controlled by the Minimum rate. The closer the control point, 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: Rate at which dosing is carried out outside the con-
trol range. The maximum dosing rate depends on the cylinder vol-
ume of the exchange or dosing unit used (see Section 3.8.6).
Rule of thumb for the maximum rate:
L/min in reaction of rate expected 0.005 L/min m in rate Max. μ ⋅ =
• Minimum rate: This parameter determines the minimum 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 behavior at the
control point. The minimum rate also has a decisive influence on
how exactly the control point can be kept constant. The smaller the