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7.10 Flow measurement
Applies to DDA-FCM control variant.
The pump accurately measures the actual flow and
displays it. Via the 0/4-20 mA analog output, the
actual flow signal can easily be integrated into an
external process control without additional
measuring equipment. See section
.
The flow measurement is based on the indicator
diagram as described in section
The accumulated length of the discharge phase
multiplied by the stroke frequency produces the
displayed actual flow. Faults e.g. air bubbles or
backpressure that is too low result in a smaller or
larger actual flow. When the "
AutoFlowAdapt
"
function is activated (see section
), the pump compensates for
these influences by correction of the stroke
frequency.
Strokes which cannot be analysed (partial strokes,
pressure differential which is too low) are
provisionally calculated based on the setpoint value
and displayed.
7.11
AutoFlowAdapt
Applies to DDA-FCM control variant.
The "
AutoFlowAdapt
" function can be activated via
the "
Setup
" menu. It detects changes in various
parameters and responds accordingly in order to
keep the set target flow constant.
This function processes information from the
pressure sensor in the dosing head. The pump
responds immediately regardless of the operation
mode by adjusting the stroke frequency.
If the target flow cannot be achieved by the
adjustments, a warning is issued.
"
AutoFlowAdapt
" operates on the basis of the
following functions:
•
FlowControl
: malfunctions are identified. See
section
.
•
Pressure monitoring
: pressure fluctuations are
identified. See section
•
Flow measurement: deviations from the target
flow are identified. See section
.
Example of "
AutoFlowAdapt
"
Pressure fluctuations
The dosing volume decreases as backpressure
increases and conversely the dosing volume
increases as the backpressure decreases.
The "
AutoFlowAdapt
" function compensates
pressure fluctuations by adjusting the stroke
frequency. The actual flow is thus maintained at a
constant level.
7.12
Auto deaeration
Dosing degassing media can result in air
pockets in the dosing head during breaks in
dosing. This can result in no medium being dosed
when restarting the pump. The "
Setup
>
Auto
deaeration
" function performs pump deaeration
automatically at regular intervals.
Software-controlled diaphragm movements
encourage any bubbles to rise and gather at the
outlet valve so that they can be removed on the next
dosing stroke.
The function works:
•
when the pump is not in the "Stop" operating
state and no alarm is active
•
during breaks in dosing (e.g.
External stop
, no
incoming pulses, etc.).
The diaphragm movements can displace small
volumes into the outlet line. When dosing strongly
degassing media, this is however virtually
impossible.
7.13
Diaphragm leak. detect.
Applies to DDA-AR control variant.
This function is only available if the pump is
equipped with a special dosing head for leakage
detection. See section
The "
Diaphragm leak. detect.
" function can be
activated via the "
Setup
" menu. It detects diaphragm
leakages. When a leakage is detected, the pump
stops and an alarm is displayed.
See also sections:
•
1.6.1 Diaphragm leakage detection (optional)
•
7.2.4 Overview of display symbols
•
Dosing accuracy is increased when
"
AutoFlowAdapt
" is activated.
