Proline Promass 83E/F/O Operation Manual - FMC Technologies

Proline Promass 83Commissioning6.5 Adjustment6.5.1 Zero point adjustmentAll measuring devices are calibrated with state-of-the-art technology. The zero point obtained inthis way is printed on the nameplate. Calibration takes place under reference operating conditions ä 108Consequently, the 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 at very small flow rates.• Under extreme process or operating conditions (e.g. very high process temperatures or very highviscosity fluids).Preconditions for a zero point adjustmentNote 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 shutoff valves upstream and/or downstreamof 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 open21Fig. 45:Zero point adjustment and shutoff valves"Caution!• If the fluid is very difficult to measure (e.g. containing entrained solids or gas) it may proveimpossible to obtain a stable zero point despite repeated zero point adjustments. In instances ofthis 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).Issue/Rev. 0.2 (12/12) MN0M022 • Page 77