Calculated parameters 7828 Density Transmitter Technical Manual
B-2 78285000_AA
B.2 BASE DENSITY REFERRAL
Base density is the density of the fluid at a specified base (or referral) temperature which
is different to the line (i.e., the actual) temperature of the fluid. Base density can be
calculated by either a Matrix referral method or by the API Referral method.
B.2.1 MATRIX DENSITY REFERRAL.
The Matrix Density Referral method uses a process of interpolation and extrapolation
between a matrix of known density and temperature reference points to determine the
liquid density at a specified base temperature different to the line temperature. A typical
referral matrix is shown below.
Temperature
Density
T
5
T
4
T
3
T
2
T
1
D
1
D
2
D
3
D
4
Line Temperature
(measured)
Line Density ρ
(measured)
Base (Referred)
Density ρ
B
(calculated)
The lines D
1
to D
4
plot the density of four product types for which the density is known at
five different reference temperatures, T
1
to T
5
. Using this information, and the measured
line density and temperature, the 7828 calculates the base density at the base
temperature.
The information required for the referral is:
• Five reference temperatures
• The density for each of four product types at the five reference temperatures(20
reference points in all)
• The base temperature, which must be one of the five reference temperatures.
All 20 reference points must be specified, otherwise 7828 cannot calculate the base
density. If you do not have all the relevant data, enter a sensible estimate for the missing
reference points.
The easiest way of entering these values is by using the Board Configuration facility of
ADView. Section 4 tells you how to do this.
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