Proline Prosonic Flow 91 Commissioning
Endress+Hauser 43
6.4 Application specific commissioning
6.4.1 Zero point adjustment
Consequently, 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 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 performing 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 pipe 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 (→ å 32).
– 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 (→ ä 95).
a0005820
Fig. 32: Zero point adjustment and shutoff valves
Performing a zero point adjustment
1. Operate the system until normal operating conditions resume.
2. Stop the flow (v = 0 m/s).
3. Check the shutoff valves for leaks.
4. Check that operating pressure is correct.
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