E
ngl
ish (
G
B)
29
6.9 Flow measurement
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.
6.10 AutoFlowAdapt
FCM control variant.
The
’AutoFlowAdapt’
function is activated in 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. Errors detected
by the sensor are processed by the software. The
pump responds immediately regardless of the
operation mode by adjusting the stroke frequency or
where necessary compensating for the deviations
with a corresponding indicator diagram.
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
).
Examples of
’AutoFlowAdapt’
Pressure fluctuations
The dosing volume decreases as backpressure
increases and conversely the dosing volume
increases as the backpressure decreases.
The
’AutoFlowAdapt’
function identifies pressure
fluctuations and responds by adjusting the stroke
frequency. The actual flow is thus maintained at a
constant level.
Air bubbles
The
’AutoFlowAdapt’
function identifies air bubbles.
The pump responds with a special indicator diagram
due to which the air bubbles are removed as a top
priority (deaeration).
If the air bubbles have not been eliminated after a
maximum of 60 strokes, the pump switches to the
’Air bubble’
warning status and returns to the normal
indicator diagram.
6.11 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 discharge valve so
that they can be removed on the next dosing stroke.
The function works:
•
when the pump is not in the
’Stop’
mode
•
during breaks in dosing (e. g. External stop, no
incoming pulses, etc.).
Note
Strokes which cannot be analysed
(partial strokes, pressure differential
which is too low) are provisionally
calculated based on the setpoint value
and displayed.
Note
Dosing accuracy is increased when
’AutoFlowAdapt’ is activated.
Note
Low volumes can be displaced into the
discharge line by the diaphragm
movements. When dosing strongly
degassing media, this is however
virtually impossible.
Summary of Contents for SMART Digital DDA
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