6.3 Dry calibration
Dry calibration is a theoretical calibration which can be carried out even though the
Cerabar S is not mounted and with a vessel filled to any height. The "empty" calibration
point is usually at the mounting point of the measuring cell. If measurement starts at
another level, then this must be included in the calculation. The requirements for a dry
calibration are:
•
The heights of the calibration points "empty" and "full" are known.
•
The density factor is known.
•
The pressure for "empty" and "full" has been calculated (p =
ρ
gh)
Selecting the operating mode enables two vessel shapes to be chosen
•
vertical – "level linear" and
•
horizontal – "level cylindrical horizontal".
Calibration
#
Matrix Path through the
menus
Entry
1
Set the display to "0" by entering a known
bias pressure
(position-dependent pressure).
V0H5
➤
Sets
bias pressure
e.g. 0.1 bar
Confirm
2
Enter the theoretical pressure for the lower
range-value (empty)
V0H1
➤
Sets 4 mA
e.g. 0.1 bar
Confirm
3
Enter the theoretical pressure for the upper
range-value (full)
V0H2
➤
Sets 20 mA
e.g. 0.3 bar
Confirm
#
Change of product?
see "Density Correction" page 32
Main group: Linearisation
4
Select operating mode
V3H0
Operation
mode
➤
Level linear
or
➤
Level
cylindrical
horizontal
Confirm
Confirm
5
Enter the level or volume at minimum level
V3H1
➤
Display at
4 mA
e.g. 0 hl
Confirm
6
Enter the level or volume at maximum level
V3H2
➤
Display at
20 mA
e.g. 100 hl
Confirm
7
Select the level or volume units
(Select unit from the tables on page 32)
V3H3
➤
Unit after
linearisation
e.g. hl
Confirm
Note!
For step 1, you can also carry out a zero correction according to the procedure described
in Chapter 5.1, page 27.
Checking after mounting
After a dry calibration, the first filling of the vessel should always be carried out under
supervision in order to identify any errors or inaccuracies which may occur.
1m
3m
0,3 bar
0,1 bar
V0H2
V3H2
V0H1
V3H1
BA187Y55
Operating mode "Level linear"
Calibration point
"empty" above
the mounting point
for the Cerabar S
V0H3
V3H1
V0H4
V3H2
2m
Full
100 hl
Empty
0 hl
BA187Y54
Operating mode "Level horizontal cylinder"
Calibration point "empty" at the
same height as the mounting
point for the Cerabar S
Note!
Cerabar S
6 Level Measurement
Hauser
35
Содержание Cerabar S PMC 731
Страница 6: ...6 Endress Hauser...
