Application-Specific Commissioning; Zero Point Adjustment - Endress+Hauser PROline prosonic flow 93 Operating Instructions Manual

PROline Prosonic Flow 93 PROFIBUS-DP/-PA
"
Endress+Hauser
6.5

Application-specific commissioning

6.5.1

Zero point adjustment

A zero point adjustment is generally not necessary.
Experience shows that the zero point adjustment is advisable only in special cases:
x To achieve highest measuring accuracy with very low flow rates.
x 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:
x A zero point adjustment can be performed only with fluids that contain no gas or solid
contents.
x 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 shut-off valves upstream and/or
downstream of the sensor or by using existing valves and gates (Fig. 69).
– Standard operation o Valves 1 and 2 open
– Zero point adjustment with pump pressure o Valve 1 open / valve 2 closed
– Zero point adjustment without pump pressure o Valve 1 closed / valve 2 open
Caution!
x 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 centre.
x You can view the zero point value currently valid using the "ZERO POINT" function
(see the "Description of Device Functions" manual).
– PROFIBUS interface / configuration program: manufacturer-specific Transducer
Block (PROSONIC 93 PBUS) o Matrix "Sensor data" o ZERO POINT CH1 (V4H1)
/ CH2 (V7H1)
– Local display: HOME o F o R o BASIC FUNCTIONS o F o R o SENSOR
DATA o F o R o CALIBRATION DATA o
Fig. 69: Zero point adjustment and shut-off valves
N
2
1
6 Commissioning
o ZERO POINT
113