Endress+Hauser Waterpilot FMX21 - Page 44

Commissioning Waterpilot FMX21
44 Endress+Hauser
9.10.2 Overview of level measurement
Measuring task Level
selection
Measured variable
options
Description Measured value
display
Calibration is
performed by
entering two
pressure-level value
pairs.
"In
pressure"
Via the "Output unit"
parameter :
%, level, volume or
mass units
• Calibration with
reference pressure
(wet calibration)
→  46
• Calibration without
reference pressure (dry
calibration) →  44
The measured value
display and the "Level
before lin" parameter
display the measured
value.
Calibration is
performed by
entering the density
and two height-level
value pairs.
"In height" • Calibration with
reference pressure
(wet calibration)
→  51
• Calibration without
reference pressure (dry
calibration) →  48
9.10.3 "In pressure" level selection Calibration without reference
pressure (dry calibration)
Example:
In this example, the volume in a tank should be measured in liters. The maximum volume
of 1 000 l (264 gal) corresponds to a pressure of 400 mbar (6 psi).
The minimum volume of 0 liters corresponds to a pressure of 0 mbar since the process
isolating diaphragm of the probe is at the start of the level measuring range.
Prerequisite:
• The measured variable is in direct proportion to the pressure.
• This is a theoretical calibration i.e. the pressure and volume values for the lower and
upper calibration point must be known.
• The values entered for "Empty calib./Full calib.", "Empty pressure/Full pressure" and
"Set LRV/Set URV" must be at least 1% apart. The value will be rejected, and a
warning message displayed, if the values are too close together. Further limit values
are not checked, i.e. the values entered must be appropriate for the sensor module
and the measuring task for the device to be able to measure correctly.
• Due to the orientation of the device, there may be pressure shifts in the measured
value, i.e. when the vessel is empty or partly filled, the measured value is not zero.
For information on how to perform a position adjustment, see →  40.
Description
1 Select the "Level" measuring mode via the
"Measuring mode" parameter.
Menu path: Setup → Measuring mode
L
WARNING
Changing the measuring mode affects the
span (URV)
This situation can result in product overflow.
‣
If the measuring mode is changed, the
setting for the span (URV) must be
checked in the "Setup" operating menu and
readjusted if necessary.
1000 l
0 l
400 mbar
r = 1
g
cm
3
A0018818
2 Select a pressure unit via the "Press. eng. unit"
parameter, here "mbar" for example.
Menu path: Setup → Press. eng. unit