Density experment, picnometer

1. Experiment N0. (1)
Measuring ⁰API gravity of Crude Oil
through measuring specific gravity by
(Pycnometer) ASTM D70

2. ⁰API: American petroleum Institute's inverted scale for denoting the 'lightness' or
'heaviness' of crude oils and other liquid hydrocarbons.
Calibrated in API degrees (or degrees API), it is used universally to expresses a
crude's relative density.
• Light crude oil has high ⁰API.
• Crude oil has low ⁰API heavy.
• Lighter crude higher its market value.
• Oil with API greater than 30º is termed light.
• Oil with API between 22º and 30º termed medium.
• Oil with API below 22º termed heavy.
• Oil with API below 10º termed extra heavy.
• Asphalt on average has an API gravity of 8°, Brent Crude of 35.5°, and gasoline
of 50°.

3. • Density is the mass of a unit volume of material
at a specified temperature and has the
dimensions of grams per cubic centimeter
(a close approximation to grams per milliliter).
• Specific gravity is the ratio of the mass of a
volume of the substance to the mass of the same
volume of water and is dependent on
temperatures.
• Specific gravity is the ratio of the density of
substance to the density of water and is
dependent on temperatures.

4. Pycnometer:
• The pycnometer is a glass flask with a close-fitting ground
glass stopper with a capillary hole through it. This fine hole
releases a spare liquid after closing a top-filled pycnometer
and allows for obtaining a given volume of measured and/or
working liquid with a high accuracy.
• It is give more security for determination the density and
depend on the comparison the mass of crude oil or derivative
petroleum at certain volume with mass the same volume of
distillate water at the same temp

6. Significance and Uses
1- Is necessary for the conversion of measured volumes
to volumes or masses, or both, at the standard reference
temperatures during custody transfer.
2- Gravity is a factor controlling the quality and pricing
of crude petroleum. However, this property of
petroleum is an uncertain indication of its quality unless
correlated with other properties.
3- Density is an important quality indicator for
automotive, aviation and marine fuels, where it affects
storage, handling and combustion.

7. Procedure:
1- Bring the samples (water and crude oil) and put
it in to cylinder then take the temperature by using
thermometer.
2- If the temperature for two samples are not equal
should making both temperature same by using
water bath (heating) or by using water container
(cooling).
3- Record the temperature.
4- Bring pycnometer dry and clean, then take mass
for the graduated cylinder in empty it will be m1.
5- Put specified volume of water in this
pycnometer then weight cylinder with water, it will
be m2.

8. 6- Put same volume of crude oil (petroleum
products) in same pycnometer then weight
cylinder with crude oil, it will be m3.
7- Calculate API Gravity of the petroleum.

9. Calculation
 To find specific gravity of crude oil at T (temperature) using
this Equation:
 To find specific gravity at temperature (15.6 ⁰C) using this
Equation:
• To find API degree using this Equation:

10. List of specific gravity and correction factors