Specific Gravity, and API Gravity for petroleum products

1. Department of Petrochemical
College of Technical Engineering
Duhok Polytechnic University


Practical Petroleum Properties lab.
??????
��
Year Level


Name of student: Muhammad Akram Muhammad

Group: A

Name of experiment: Determination of Specific Gravity, and API Gravity for
petroleum products

No. of experiment: 2

Date: 18/4/2016

2. Objective:
Determination of Specific Gravity, and API Gravity for petroleum products
Introduction:
Determining the density, specific gravity and API gravity of the fluid is very
important to classify the fuel. This experiment will shows us how to
determine API and S.G via two method. Density is mass per unit volume or
Density is a characteristic property of a substance. The density of a substance
is the relationship between the mass of the substance and how much space it
takes up (volume). Specific gravity the ratio of the density of any substance
to the density of some other substance taken as standard, water being the
standard for liquids and solids, and hydrogen. API gravity is used to quantify
the quality of petroleum products and it has ranges that measures the quality.
And it depends on specific gravity , the higher S.G the lower API gravity.

Apparatus and material:
 Hydrometer:
Pykonmeter 50 ml:
Graduated cylinder:
Scientific balance:

3. Procedure:

Hydrometer method:
At first we take a suitable graduated cylinder 500 ml and it should be clean. The
cylinder should be big enough because when we put the hydrometer it should
(move) floats easily in the cylinder. So, we fill the cylinder with the sample (in
our experiment we just used kerosene for this method). After filling the cylinder
with the kerosene we allowed sufficient time for the hydro meter to come to rest.
And when the hydrometer is flowed freely we took the scale reading. And at the
end we brought out the hydrometer and cleaned it.

Pycnometer method:

At first we took the emptied pyconmeter and weigh it (??????
0). Then we filled the
pyconmeter with the sample that we wanted and weigh it again (??????
1). (To yield the
weight of the sample we subtract ??????
1 from ??????
0.) The volume of the pyconmeter
that we used for kerosene and also gasoline was 5.340 ml and for kerosene was
5.340ml. After those steps we measure the density of fluid and API gravity and
Specific Gravity according to what we did in the lab.


API gravity = 141.5/S.G(at 15.6 °C) – 131.5

Note:
 API gravity > 40 paraffinic (or light) based crude oil
API gravity = 33-40 mixed (or intermediate) based crude oil
API gravity < 33 naphthenic ( asphaltic or heavy)based crude oil

4. Calculations:

Hydrometer method
The specific gravity of kerosene is 0.790
API gravity =
141.5
0.790
- 131.5 →API gravity = 179.1 – 131.5 = 47.61

Hydrometer method
The specific gravity of gasoline is 0.820
API gravity =
141.5
0.820
– 131.5 → API gravity = 172.5 – 131.5 = 41.06

Pycnometer method

Kerosene

??????
0 of empty pycnometer = 14.70 g
??????
1 of filled pycnometer = 18.85 g
Volume of pycnometer = 5.340 ml
M= ??????
1-??????
0 =→M= 18.85- 14.70= 4.15 g

D=
&#3627408448;
1−??????0
&#3627408483;&#3627408476;&#3627408473;&#3627408482;&#3627408474;&#3627408466; &#3627408476;&#3627408467; &#3627408477;??????&#3627408464;&#3627408475;&#3627408476;&#3627408474;&#3627408466;&#3627408481;&#3627408466;&#3627408479;
=→
4.15
5.340
= 0.777

S.G =
&#3627408439;&#3627408440;&#3627408449;&#3627408454;??????&#3627408455;??????
&#3627408465;&#3627408466;&#3627408475;&#3627408480;??????&#3627408481;?????? &#3627408476;&#3627408467; &#3627408484;??????&#3627408481;&#3627408466;&#3627408479;
→
0.777
0.999
= 0.777

API gravity =
141.5
0.777
- 131.5 = 181.6 - 131.5= 50.6

5. Gasoline
??????
0 of empty pycnometer = 14.70 g
??????
1 of filled pycnometer = 19.00 g
Volume of pycnometer = 5.340 ml

M= ??????
1-??????
0=→M= 19.00- 14.70= 4.3g

D =
&#3627408448;1− ??????0
&#3627408483;&#3627408476;&#3627408473;&#3627408482;&#3627408474;&#3627408466; &#3627408476;&#3627408467; &#3627408477;??????&#3627408464;&#3627408475;&#3627408476;&#3627408474;&#3627408466;&#3627408481;&#3627408466;&#3627408479;
= →
4.3
5.340
= 0.805

S.G =
&#3627408439;&#3627408440;&#3627408449;&#3627408454;??????&#3627408455;??????
&#3627408465;&#3627408466;&#3627408475;&#3627408480;??????&#3627408481;?????? &#3627408476;&#3627408467; &#3627408484;??????&#3627408481;&#3627408466;&#3627408479;


S.G =
0.805
0.999
= 0.805

API gravity =
141.5
0.805
- 131.5

= 175.34−131.5=44.27


We can classify them according to the ranges of API, that have been wrote after
procedure

6. Discussion:

In the lab we we measured the API and S.G of kerosene and gasoline . we measured
the API of kerosene and gasoline by hydrometer and pycnometer, on hydrometer
method the API value of gasoline sample was 41.06 but in pycnometer method API
was 44.27. The pycnometer method is more accurate because hydrometer is affected
by many things that makes reading not accurate

1- Explain which method is much accurate?

Method two (pycnometer is more accurate than the hydrometer and the reasons
belongs to those factors that affect the hydrometer like temperature, carbon
dioxide, and presence of alcohol..

2- What are factor effecting on the hydrometer?

The factors that effects the hydrometer are:
 temperature that causes the change in density
 carbon dioxide
 presence of alcohol

3- What are the advantages of API value?

The more API gravity value of crude oil is more expensive and more effectual
because its contain more gasoline and it is the most wanted product at the whole
world. The other advantage of API gravity value that we can determine the
sulphur contain in crude oil , the higher value if API gravity means the less
contain of sulfur , the high levels of sulfur contains can be toxic and dangerous
and can cause breathing hazards .