HYDAC HMG 3000 - Manual (Page 21)

HMG 3000 Page 21
Edition 11/2007 - V02 R01-S02 Stock no.: 669712
Connect the pressure transmitter
hydraulically so that the two instruments are
subjected to the same pressure. The ideal
for recording curves is connecting to a test
rig on which you can increase the pressure
slowly from 0 bar to the full measurement
range of the pressure transmitter and back
again.
However, the minimum requirement is to
record the curves/measured values in the
pressure range in which the differential
measurement is to take place later.
In the example above (to measure the filter
contamination level) both pressure
transmitters might be fitted to the inlet side of
the filter, e.g. using T-fittings and then, with
the machine running, the curve could be
recorded.
When these pre-conditions are in place,
select Record characteristic curve. This
brings up a display showing 0 to 100% of the
whole measurement range. If you increase
the pressure you will see from the blue bar
that measured values are being recorded in
this pressure range.
If the measured values remain under the red
line, this means that not enough values have
been recorded in this range. To achieve
maximum accuracy for differential
measurement, the recorded measured
values should at least be in the area
between the red and the green line. After
this, select Stop recording and you can quit
the menu. The curve is now automatically
taken into account for the differential
measurement using these two pressure
transmitters.