RMA42
Appendix
Hauser
49
11
Appendix
The following tables show all the parameters available in the configuration menu. The values
configured at the factory are marked in bold.
11.1
Further explanations on the differential pressure
application at level measurement
At both universal inputs pressure sensors are connected.
With the following calculation steps the volume in the CV channels is finally calculated:
1
st
Calculation Step: Calculation of the filling level
Both pressure sensors provide the actual pressure at the installation point.From both pressures
(possibly adjusted for an offset; this has to be set in AI1 respectively AI2) a pressure difference (
Δ
p)
is determined. If the pressure difference is divided through the density of the medium multiplied
with the gravitational acceleration the measured height is gained..
Level h=
Δ
p/(
ρ
*g)
The following units form the basis of the calculation:
Density
ρ
: [kg/m]
Pressure p: [Pa] or [N/m
2
]
The gravitational acceleration is defined by a constant:
Gravitational acceleration g=9.81m/s
2
"
Caution!
If the calculation is to be carried through correctly the measured signal (e.g. in mbar) has to be
converted into the according unit Pascal (Pa).
This is achieved by a conversion factor. Conversion factors can be found in the table
Examples for the conversion:
Water: density
ρ=
1000kg/m
3
Pressure measurement: pressure1 (bottom): Scale 0…800mbar (0…80000 Pa);
Present value: 500mbar (50000 Pa)
Pressure measurement: pressure2 (top): Scale 0…800 mbar (0…80000 Pa);
Present value: 150mbar (15000 Pa)
When using Pascal:
When using mbar:
h = b *
Δ
p
Calculation of the correction factor b:
b = 1/(
ρ
*g)
for water: b = 1/(1000*9.81) = 0,00010194
Tables and examples for the conversion of application related units into the defined values kg/m
3
and Pa or N/m
2
:
• 1 bar = 0.1 N/mm
2
= 10
5
N/m
2
= 10
5
Pa
• 1 mbar = 1 hPa = 100 Pa
h =
1
* (50000-15000 Pa) = 3.57 m
1000 kg/m
3
*9.81 m/s
2
h =
1
* ((500-150 mbar)*(1,0000*10
2
))= 3.57 m
1000 kg/m
3
*9.81 m/s
2
