Endress+Hauser NXA820 - Page 32

Calculations Tankvision
32 Endress+Hauser
Typical table example: 54B (1980)
L00-NXA82xxx-16-00-00-xx-046
Special corrections
VCF Chemical 1
L00-NXA82xxx-16-00-00-xx-049
with:
•D
Ref
= Reference density
•T
Obs
= Actual or observed temperature
•T
Ref
= Reference Temperature
• A-E = Configurable coefficients
TCF Method
L00-NXA82xxx-16-00-00-xx-050
with:
•K
0
, K
1
, K
2
, K
3
, K
4
= Customer coefficients
• t = Actual product temperature
•T
Ref
= Reference Temperature
For the VCF we can write:
L00-NXA82xxx-16-00-00-xx-051
With the TCF method the p
Ref
can be calculated with p
Obs
/ VCF (when manual p
Obs
is
provided) and an actual p
Obs
can be calculated with p
Ref
x VCF, when p
Ref
is known and
no actual p
Obs
is available.
The range of application:
Density, kg/m³ Temperature, °C
653.0 to 778.5 -18.0 to 90.0
779.0 to 824.0 -18.0 to 125.0
824.5 to 1075.0 -18.0 to 150.0
VCF = EXP [- t(1.0+0.8t)]aD aD
15 15
K = 346.4228
0
K = 0.4388
1
where:
+
Dt = DEGC - 15.0
a
15
=
K
0
K
1
p
15
p
15
2
VCF = {D - A 10E3 (T -T) - B 10E3 (T - T)
- C 10E3 (T -T) - D 10E3 (T -T)
- E 10E3 (T -T) } / D
Ref Obs Ref obs Ref
Obs Ref Obs Ref
Obs Ref Ref
´´ ´´
´´ ´´
´´
2
3 4
5
TCF = K0 + K1t + K2´ D ´ D ´ D ´ Dt + K3t + K4 t
234
Dt = t - T
Ref
TCF = 1 - TCF (T - T)´
Obs Ref