Proline Promass 80H, 83H
18
Hauser
Zero point adjustment
All measuring devices are calibrated to state-of-the-art technology. The zero point determined in this way is
imprinted on the nameplate.
Calibration takes place under reference conditions.
→
Page 12 ff.
Therefore, a zero point adjustment is generally
not
required!
Experience shows that the zero point adjustment is advisable only in special cases:
• When the highest measuring accuracy is required and the flow rates are very low.
• Under extreme process or operating conditions (e.g. very high process temperatures or very high viscosity
fluids).
Please note the following before carrying out the adjustment:
• The adjustment can only be performed with fluids that have no gas or solid contents.
• Zero point adjustment is performed with the measuring tubes completely filled and at zero flow (v = 0 m/s).
This can be achieved, for example, with shutoff valves upstream and/or downstream of the sensor or by
using existing valves and gates.
– Normal operation
→
valves 1 and 2 open
– Zero point adjustment
with
pump pressure
→
valve 1 open / valve 2 closed
– Zero point adjustment
without
pump pressure
→
valve 1 closed / valve 2 open
a0003601
Zero point adjustment and shutoff valves
Inlet and outlet runs
There are no installation requirements regarding inlet and outlet runs.
Length of connecting cable
Max. 20 meters (remote version)
System pressure
It is important to ensure that cavitation does not occur, because it would influence the oscillation of the
measuring tube. No special measures need to be taken for fluids which have properties similar to water under
normal conditions.
In the case of liquids with a low boiling point (hydrocarbons, solvents, liquefied gases) or in suction lines, it is
important to ensure that pressure does not drop below the vapor pressure and that the liquid does not start to
boil. It is also important to ensure that the gases that occur naturally in many liquids do not outgas. Such effects
can be prevented when system pressure is sufficiently high.
Therefore, the following locations should be preferred for installation:
• Downstream from pumps (no danger of vacuum)
• At the lowest point in a vertical pipe
1
2
