Commissioning
CNGmass DCI
52
Hauser
6.5
Adjustment
6.5.1
Zero point adjustment
All measuring devices are calibrated with state-of-the-art technology.
The zero point obtained in this way is printed on the nameplate.
Calibration takes place under reference operating conditions
Consequently zero point adjustment is generally
not
necessary for CNGmass DCI!
Experience shows that the zero point adjustment is advisable only in special cases:
• To achieve highest measuring accuracy also with very small flow rates.
• Under extreme process or operating conditions (e.g. very high process temperatures).
Preconditions for a zero point adjustment
Note the following before you perform a zero point adjustment:
• Adjustment can only be performed on homogeneous fluids.
• Zero point adjustment is performed 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
Fig. 30:
Zero point adjustment and shutoff valves
"
Caution!
• The currently valid zero point value can be viewed using the "ZEROPOINT" function
(
È
"Description of Device Parameters" manual).
1
2
