KROHNE Summit 8800 Vol 2 - Manual (Page 29)

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08/2013 - MA SUMMIT 8800 Vol2 R02 en
SUMMIT 8800 METERING PRINCIPLES 03
3 .6 Liquid normalisation
As with gas also oil flow is measured by meters using a variety of different measurement prin-
ciples, most based on volume flow, some based on mass flow. Examples are turbine meters,
orifice meters, Coriolis meters and ultrasonic meters. In all cases the line flow is measured.
The problem with this is that two measurements in the same pipe cannot be compared, due to
difference in temperature, (to a lesser extend) pressure and possibly the type of product. This
also means that billing of the oil will not be possible as no fixed tariff can be applied.
For this reason a flow computer is used to “normalize” the oil flow to standard (or base) condi-
tions, such as:
Temperature 15 or 20 oC or 60 oF
Pressure 1.01325 bar or 14.73 psi
So from the input density, the standard density is calculated by correcting for pressure and
density. Then, from the standard density, the meter density is calculated, by again correcting for
pressure and density.
Figure 11 Density calculations for oil