LPG quantity calculation from liquid density
ADM003GVAE1005 305
Step 8
Liquid mass is calculated from liquid density at 15°C and corrected liquid volume
at 15°C. The units here are tonnes.
Step 9
Total tank volume is corrected for temperature and pressure using the overall
mean tank temperature. This is best calculated for the liquid volume, liquid
temperature and total volume and vapor temperature as:
The correction is then carried out as:
The correction for pressure is applied as in step 6 except that 3 replaces F in the
calculation of the correction factor. S is the previously calculated value.
Step 10
Vapor volume is calculated from corrected liquid volume at tank conditions (Step
5) and total tank volume corrected to measured conditions (Step 9) as:
Step 11
Vapor density may be calculated from liquid density, vapor temperature and vapor
space pressure as follows:
ML = VLC15 x DENL15 / 1000
Where ML = Liquid Mass
TAV = (TL x VLC + (VT - VLC) x TV) / VTC
TAV = Average overall tank temperature
TL = Temperature of liquid
TV = Temperature of vapor
VTC = Total tank volume
CORRT2 = 1 + 3 x αT x (TAV - 15)
Where αT = Coefficient of thermal expansion of the tank /°C
i.e. CORRP2 = 1 + 3 x S/YOUNG
VTC = VT x CORRT2 x CORRP2
Where VTC = Volume of tank corrected for temperature and pressure
W = VTC - VLC
Where VV = Vapor volume
VTC = Total tank volume
VLC = Corrected liquid volume
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