HYDAC HMG 3000 - Manual (Page 19)

HMG 3000 Page 19
Edition 11/2007 - V02 R01-S02 Stock no.: 669712
A drop-down list is also provided for
selecting the Unit (of measurement). You
also have the option of defining your “other
unit”
(uppermost line of the drop-down list).
The cursor then jumps to the input box and
a small triangular arrow appears as the
insertion point
. Enter the new unit using
the combination keypad, e.g. ”kPa” for
kilopascal.
To enter additional characters, move the
triangle insertion point to the desired
position and enter the characters. Conclude
your entry via OK so that your unit of
measurement is stored.
Decimal format
: Here you can specify how
many decimal places are to be used when
recording and displaying the measured
values.
In addition to the settings described above,
Channel B
has two further measurement
options. In the Mode drop-down menu you
now also have the menu options Pressure
difference dP
and Orifice measurement
Q=f(dP) . With Pressure difference dP the
HMG 3000 gives you the opportunity to
display the difference in pressure between
channel A – channel B with a very high
degree of accuracy. This can be used, for
example, to determine if a filter is clogged,
by measuring the pressure differential.
The function Orifice measurement Q=f(dP) enables you to carry out a flow rate
measurement by measuring the differential pressure at a flow rate measurement orifice (e.g.
HYDAC EVS 1000). For both these modes HYDAC HSI pressure transmitters with the same
measurement range must be connected to channel A and channel B. The differential
measurement range is produced automatically, being
± 10% of the measurement range of
the pressure transmitters connected. The accuracy of the HSI pressure transmitters is
≤±0.5%FS. This means that one 100 bar pressure transmitter might measure 50 bar
pressure as being 49.5 bar, and another might measure it as 50.5 bar. These pressure
transmitter errors can be compensated for by recording a correction curve. After correctly
recording a curve, the accuracy for differential measurement is
≤±0.1% of the differential
measurement range.