UNIVERSITY OF ZAKHO

Faculty of Engineering

School of Petroleum Engineering

Practical Petroleum Properties Lab.

2nd Year Level

Name of student : Bilal Mohammed Taha Class: A Name of Experiment: Measurement of Density, S.G, and API gravity for petroleum fraction. No. of Experiment: 2 Date: 13/12/2015

Experiment No. -2-

Measurement of Density, Specific Gravity, and API Gravity

Objective:

Determination of Specific Gravity, and API Gravity for petroleum products

Introduction:

Determining the density, specific gravity and API gravity of the fliud is very important to classify the fuil. 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 priducts 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:

ü Hydrometer: ü Pyconmeter: ü Graduated cylinder: ü Scientific balance:

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 hygrometer it should (move) floats easily in the cylinder.

So, we fill the cylinder with the sample (in our experiment we just used diesel for this method). After filling the cylinder with the diesel 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 (M1). Then we filled the pyconmeter with the sample that we wanted and weigh it again (M2). (To yield the weight of the sample we subtract M2 from M1.)

The volume of the pyconmeter that we used for kerosene was 5.305 ml and for diesel was 4.928ml.

After those steps we measure the 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:

Ø API gravity > 40 paraffinic (or light) based crude oil Ø API gravity = 33-40 mixed (or intermediate) based crude oil Ø API gravity < 33 napthenic ( asphaltic or heavy)based crude oil

Calculations:

Hydrometer method

The specific gravity of diesel is 0.832

API gravity = � � � .

. - 131.5 èAPI gravity =

� � � .. � � �

– 131.5 = 38.572

(we didn’t measured the S.G of kerosene by hydrometer)

Pycnometer method

Kerosene

M1 of empty pycnometer = 14.723 g M2 of filled pycnometer = 18.882 g

Volume of pycnometer = 5.305 ml

M= M2-M1 =èM= 18.882- 14.723= 4.159g

k= = . � � �. � � �

= 0.784

S.G = kw = . � � � = 0.784

API gravity = � � � .

. - 131.5

= � � � .

. � � � - 131.5 = 48.8

Deisel

M1 of empty pycnometer = 15.295 g M2 of filled pycnometer = 19.357 g

Volume of pycnometer = 4.928 ml

M= M2-M1 =èM= 19.357- 15.295= 4.062g

d= =4.062

4.928 = 0.82427

S.G = dw = . � � � � � = 0.82427

API gravity = � � � .

. - 131.5

= � � � .. � � � � �

- 131.5 = 40.167

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

Discussion: In the lab we we measured the API and S.G of kerosene and Diesel . we measured the API of diesel by hydrometer and pycnometer(but we didn’t measured the S.G of kerosene via Hydrometer ), on hydrometer method the API value of diesel sample was 38.57 but in pycnometer method API was 40.167. 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:

Ø temperature that causes the change in density Ø carbon dioxide Ø 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 .

References:

www.wikipedia.org

http://whatis.techtarget.com

http://study.com