Nivus OCM F, Инструкция по эксплуатации

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Parameter Setting
OCM F - rev. 05 / 06.04.2018 page 77
Zero point drift.
Due to physical reasons the pressure measurement cell is subject to zero point drift. It is
recommended to adjust the pressure sensor to the zero point regularly (recommended
interval: 6 months).
Required values have to be investigated with the sensor being removed if possible or if the
water level is as low as possible. The correct filling level has to be investigated as accurate
as possible before adjusting by using another suitable measurement method (value = 0 if
the sensor has been removed from the medium). Enter the investigated value as reference.
Measurement error
Investigating the zero point of the pressure measurement cell is often carried out by meas-
uring the current filling level with a yardstick, a ruler or similar without removing the sensor.
After the ruler or similar has been held into the medium, the respective reading is entered
as reference value.
If this procedure is performed in flowing water the turbulence emerging on the ruler may
lead to measurement errors. This is why the filling level for reference measurement pur-
poses has to be measured always from top down (see Fig. 27-1).
25.2 CAL submenu “Flow Velocity”
Fig. 25-3 Submenu flow velocity
>min. velocity<
Defines the minimum flow velocity range measured and evaluated by
the transmitter.
Default setting: -4 m/s
The minimum velocity can be set to “0” as soon as it is not desired to
measure the negative flow direction.
>max. velocity< Defines the maximum flow velocity range measured and evaluated
by the transmitter.
Default setting: 4 m/s
Positive and negative velocities are not measured
If the maximum value is set to “0” it is not possible to measure and to issue the positive
velocity!
If the minimum value is set to “0” it is not possible to measure and to issue the negative
velocity!