Commissioning Proline Promass 83 PROFIBUS DP/PA
112 Endress+Hauser
6.9 Adjust
6.9.1 Zero point adjustment
All Promass 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. → Page 151 ff.
Consequently, the zero point adjustment is generally not necessary for Promass!
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 or very high
viscosity fluids,
Preconditions for a zero point adjustment
Note the following before you perform a zero point adjustment:
• A zero point adjustment can be performed only with fluids that contain 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 shut-off 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
F06-xxxxxxxx-11-00-00-xx-001
Fig. 50: Zero point adjustment and shut-off valves
"
Caution!
• If the fluid is very difficult to measure (e.g. containing entrained solids or gas) it may prove
impossible to obtain a stable zero point despite repeated zero point adjustments. In instances of
this nature, please contact your E+H service center.
• You can view the currently valid zero point value using the “ZERO POINT” function (see the
“Description of Device Functions” manual).
1
2
To Next Page
Loading...
