Marine Diesel Oil (MDO) is a type of

fuel oil Fuel oil is any of various fractions obtained from the distillation of petroleum (crude oil). Such oils include distillates (the lighter fractions) and residues (the heavier fractions). Fuel oils include heavy fuel oil, marine fuel oil (MFO), b ...

and is a blend of

gasoil Fuel oil is any of various fractions obtained from the distillation of petroleum (crude oil). Such oils include distillates (the lighter fractions) and residues (the heavier fractions). Fuel oils include heavy fuel oil, marine fuel oil (MFO), b ...

and

heavy fuel oil Heavy Fuel Oil (HFO) is a category of fuel oils of a tar-like consistency. Also known as bunker fuel, or residual fuel oil, HFO is the result or remnant from the distillation and cracking process of petroleum. For this reason, HFO is contaminate ...

, with more gasoil than intermediate fuel oil used in the

maritime Maritime may refer to: Geography * Maritime Alps, a mountain range in the southwestern part of the Alps * Maritime Region, a region in Togo * Maritime Southeast Asia * The Maritimes, the Canadian provinces of Nova Scotia, New Brunswick, and Pri ...

field. Marine Diesel Oil is also called "Distillate Marine Diesel". MDO is widely used by medium speed and medium/high speed marine diesel engines. It is also used in the larger low speed and medium speed propulsion engine which normally burn residual fuel. Those fuels result from a catalytic cracking and

visbreaking A visbreaker is a processing unit in an oil refinery whose purpose is to reduce the quantity of residual oil produced in the distillation of crude oil and to increase the yield of more valuable middle distillates ( heating oil and diesel) by the r ...

refinery. Marine diesel oil has been condemned for its nimiety of sulfur, so many countries and organizations established regulations and laws on MDO use. Due to its lower price compared to more refined fuel, MDO is favored particularly by

shipping industry Maritime transport (or ocean transport) and hydraulic effluvial transport, or more generally waterborne transport, is the transport of people ( passengers) or goods (cargo) via waterways. Freight transport by sea has been widely used thro ...

Specification

ISO 8217 of the

International Standards Organization The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Art ...

(ISO) is the primary standard of MDO. Marine fuels range in

viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the int ...

from less than one centistoke (cSt) to about 700 cSt at 50°C (122°F). (1 cSt = 1 mm2/s.) And higher viscosity grades are preheated during use to bring their viscosity into the range suitable for

fuel injection Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines. All com ...

(8 to 27 cSt). But MDO does not need to be preheated before using. According to Chevron, MDO has a sulfur limit varies from 1 to 4.5 percent by mass for different grades and Sulfur Emission Control Areas (SECAs).

Manufacturing procedure

MDO is made from a catalytic cracking and

refinery. The catalytic cracking operation breaks large molecules into small molecules. It happens in high temperature and with appropriate

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

Visbreaking A visbreaker is a processing unit in an oil refinery whose purpose is to reduce the quantity of residual oil produced in the distillation of crude oil and to increase the yield of more valuable middle distillates ( heating oil and diesel) by the r ...

is a process that turn the bottom product of the vacuum unit, which has extremely high

, into lower

, marketable product. In visbreaking, a relatively mild thermal cracking operation is performed. And the amount of cracking is limited by the overruling requirement to safeguard the heavy fuel stability.

Use

The market of MDO is much smaller than on-highway diesel. According to the a 2004 U.S. Diesel Fuel Sales statistics from U.S. Department of Energy, Energy Information Administration, Marine shipping only takes 3.7% of total diesel market. On the other hand, On-highway diesel takes up 59.5% of diesel fuel sales. This small sales share of MDO is due to the high proportion of petroleum resid that made it can be used on large marine engines. According to Chevron, petroleum resid, or inorganic salts, in the fuel result in injector tip deposits that prevent the injector from creating the desired fuel spray pattern. But those low-speed, large marine diesel engines are appropriate for using fuel containing large amounts of petroleum resid.

Regulations and restrictions

The

International Maritime Organization The International Maritime Organization (IMO, French: ''Organisation maritime internationale'') is a specialised agency of the United Nations responsible for regulating shipping. The IMO was established following agreement at a UN conference ...

(IMO) develops regulations for marine shipping. Among those regulations, MARPOL (the International Convention for the Prevention of Pollution from Ships) is the most widely adopted one. MARPOL is the main international convention covering the prevention of operational or accidental pollution of the marine environment by ships. Inside IMO, there is a committee called MEPC(Marine Environment Protection Committee). MEPC has meetings periodically and discuss resolutions to current

marine pollution Marine pollution occurs when substances used or spread by humans, such as industrial, agricultural and residential waste, particles, noise, excess carbon dioxide or invasive organisms enter the ocean and cause harmful effects there. The major ...

by adding amendments to its official documents.

References

Liquid fuels Diesel fuel {{energy-stub