NT216C GB1
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1-2: Sound velocity in petroleum products
– Relation with density :
The sound velocity in any fluid can be related to some other physical characteristics such
as density but also fluid pressure (P) and temperature (T) , mixture ratio if two or many
products …and another data which presents a good analogy for liquids : the compressibility.
For most of the refined products, experiences show a linear proportional relationship
between density and sound velocity at given P and T. We name them
“Aligned Products“
by opposition to some which present some divergence and are named “Petrol non-aligned
products” as we can observe when gasoline includes additives (old leaded gasoline, Grade
95 or 98 Premium Super
with MTBE…), which influence compressibility.
The addition of alcohol in gasoline or vegetal origin oil in diesel does some slight deviation,
but with no consequence for interface detection capability.
Sometimes such a divergence becomes an advantage and permits to detect a change that
is called interface, between two successive products that have the same density.
Meanwhile, end user must take care about a possible confusion between two successive
products having a very closed density.
Other products that
don’t belong to the same family can be not aligned.
Here below, we give a list of usual products with their approximate density and sound
velocity characteristic at 1 bar pressure (but propane & butane ) and 15/20 °C temperature.
Product Name
Density ( kg / m
3 )
Sound Velocity ( m/s )
Liquid *Propane
500
810
Liquid Butane
580
920
Light Naphta
670
1100
JP4
– Jet petroleum
760
1240
Jet A1
795
1290
Spirdane
770
1260
Tetramere
775
1270
Kerosene HT
800
1310
Diesel
820
1340
Domestic Fuel
840
1370
Petrol
750
1230
Leaded Gasoline Normal
745
1190
Leaded Gasoline Premium 745
1170
Eurosuper 95
775
1220
Crude Oils
850
–900
1340
– 1430
Xylene
860
860
Benzene
870
870
Methanol
790
1155
Ethanol
785
1195
Ethyl alcohol
825
1205
Water
1000
1480
Aligned
Products
Not aligned
Or other
Products
