Endress+Hauser prolevel FMC 661, Operating Instructions Manual

Page: 33 / 56

Example: display in hl
display for p
zero
≠
0
Calculate the pressure in mbar acting at the sensor for the desired »empty« level and
the span (»full« - »empty«):
p
mbar
= 10 x
ρ
(kg/dm
3
) x g (m/s
2
) x
∆
h (m)
For 0.0 m water, display = 50 hl
For 10.0 m water, display = 2000 hl
Span (50
…
2000 = 1950) = 10 m
•
p
zero =
10 x 1.0 x 9.807 x 0.0 = 0.0 mbar
p
1950 =
p
span
= 10 x 1.0 x 9.807 x 10.00 = 980.7 mbar
•
Offset = p
zero
= = 0.0 mbar
Sensitivity = p
span
/span = 980.7/1950 = 0.5029 mbar/hl
Sensor calibration
# Matrix Entry Remarks
1 V0H2 e.g. 2000 Full level (100%)
2 - »E« Register entry
3 V3H1 0.0 Offset in mbar
4 - »E« Register entry
5 V3H2 e.g. .5029 Sensitivity mbar/hl
6 - »E« Register entry
The Prolevel now measures 0 at 0 mbar — a
negative level offset must be entered, p. 25
7 V3H4 e.g. -50 Level offset
8 - »E« Register entry
Next step
…
Set analogue outputs and relays in the units used for calibration, e.g. hl, see p. 30
…
33.
Density correction for
hydrostatic sensor If the product changes after calibration, the measurement can be corrected by entering
a density factor at V8H7:
Factor = old factor x new density
old density
The measured value is divided by the factor before display.
Note!
•
For an automatic density correction using an additional external limit switch see
»Calibration Correction« in Chapter 5
Note!
VH
0 0
VH
0 0
50
2000
»Empty« = 0.0 m
»Full« e.g. 10 m
p
empty
=
ρ
x g x 0.0
e.g. = 0 mbar
span =
2000 -
50 =
1950
=
e
.g.
10
m
BA142_35
negative level offset
sensor zero
point
display
Fig. 4.9:
Parameters for dry calibration, display in hl
Prolevel FMC 661 Chapter 4: Level Measurement
Hauser 29