Application-Specific Commissioning; Zero Point Adjustment - Endress+Hauser Proline Prosonic Flow 93T Portable Operating Instructions Manual

Commissioning
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6.4

Application-specific commissioning

6.4.1

Zero point adjustment

Zero point adjustment is generally not necessary!
Experience shows that the zero point adjustment is advisable only in special cases:
• To achieve highest measuring accuracy with very low 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 have no gas or solid contents.
• Zero point adjustment is performed with the measuring tube 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 measuring range or by using existing valves and gates ( ä 44).
– Standard 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
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 Endress+Hauser service center.
• You can view the currently valid zero point value using the ZERO POINT function.
Fig. 43: Zero point adjustment and shutoff valves
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Proline Prosonic Flow 93T Portable
Endress+Hauser
A0011585