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مجلة النفط والتعاون العربي
161
العدد
- 2017
أربعون
المجلد الثالث و ال
2016
أوابك العلمية لعام
�
ص لبحوث العلمية الفائزة بجائزة
�
عدد خا
40
30
EU countries earlier. In any case, there is no escaping the fact that the world burns
five times the used oil that it re-refines.
Finally the re-refining of used oil to produce base oils is found to be much more
favourable environmentally than the production of virgin base oils
106
. Global
warming potential is 2 times less, nutrification is 3-4 times less, acidification and
fine particulates (PM 10) is more than 5 times less and carcinogenic risk is 10-20
times less
106
.
Quality, Groups and Drain Periods:
The purposes of lubricating oils are many
9
. They are expected to keep moving
parts apart thereby reducing wear, reduce friction and improve efficiency, transfer
heat, carry away contaminants and debris, transmit power in case of hydraulic
oils and prevent rust and corrosion.
In order to do so, lubricating oils must meet certain standard specification that
may have to be certified by an independent body with a well-equipped testing
laboratory especially for engine oils.
The US Society of Automotive Engineers was the first to classify lubricating oils
according to viscosity and consumers still see their symbol on lube containers to
indicate the viscosity class.
However, the more famous specifications now are those of the American
Petroleum Institute (API) and their comparative counterpart European
Automobile Manufacturers Association (ACEA) in addition to the original
equipment manufacturers (OEM) in some cases.
In the API system base oils are divided into five categories
1, 9, 21
according to
constituents and performance level as measured by the viscosity index.
The API Groups:
Group-I: Base stocks with less than 90% saturated constituents or greater than
0.03% sulpher and have a viscosity index greater than or equal to 80 and less than
120. They are generally prepared by solvent extraction processes.
Group-II: Base stocks contain greater than or equal to 90% saturated constituents
and less than or equal to 0.03% sulpher and have a viscosity index greater than or
equal to 80 and less than 120. They are manufactured by hydro-treating and
hydrocracking and either solvent or catalytic dewaxing to have better properties