Fig. 15: Adjustment flow measurement with V-notch
Select in the DTM window "Linearization" the option "Flow" and then
the used flume (in the above example V-notch).
Select in the DTM window "Scaling" under "Parameter" the option
"Flow". Finally the allocation of a value must be carried out, i.e. the flow
volume is assigned to the 0 and 100 % value. As the last step, select
the requested meas. unit. For above example: 0 % = 0 and 100 % =
400, meas. unit m³/h.
First of all decide if you want to use a relay and/or a current output. In
the DTM window "Outputs" you can use any of the three outputs as
long as these are not yet used for other tasks.
Finally select under "Mode" (relay) or "Output characteristics" (current
output) the option "Flow volume pulse" or "Sampling pulse". Enter
under "Pulse output all" the flow volume after which a pulse should be
outputted (e.g. 400 m³ corresponds to one pulse per hour with a flow
volume of 400 m³/h).
In mode "Sampling pulse" an additional pulse is outputted after a
defined time. This means that a timer is started after each pulse after
which another pulse is outputted. This applies only if already a pulse
was outputted after exceeding the flow volume.
Due to sludge at the bottom of the flume, it can happen that the min.
adjustment originally carried out can no longer be reached. Therefore
small quantities will continuously enter the flow volume detection
despite the "empty" flume. The option "Min. flow volume suppression"
offers the possibility to suppress measured flow volumes below a
certain percentage value for the flow volume detection.
If a flow measurement is set up, the flow value can also be summed up
and displayed as flow volume. The graph can be selected in the menu
item "Display". The following parameters must be adjusted for the
totalizer:
l Measuring unit: Selection of the unit by which the totalizer adds.
l Indicating format: Selection of the indicating format (number of
decimal positions of the counter)
Linearisation curve
Scaling
Outputs
Totalizer
VEGAMET 391 • 4 … 20 mA/HART signal conditioning instrument 49
8 Application examples
36032-EN-091116
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