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Quality Standard for Rapeseed Oil as a Fuel (RK-Qualitätsstandard)
Properties /Contents	Unit	Limiting Value		Testing Method
		min.	max.
Characteristic properties for Rapeseed 0il
Density (15ºC)	kg/m3	900	930	DIN EN ISO 3675 DIN EN ISO 12185
Flash Point by P.-M.	ºC	220	-	DIN EN 22719
Calorific Value	kJ/kg	35000	-	DIN 51900-3
Kinematic Viscosity (40ºC)	mm2/S	-	38	DIN EN ISO 3104
Low Temperature Behaviour	-	-	-	Rotational Viscometer (testing conditions will be developed)
Cetane Number	-	-	-	Testing method will be reviewed
Carbon Residue	Mass-%	-	0.40	DIN EN ISO 10370
Iodine Number	g/100 g	100	120	DIN 53241-1
Sulphur Content	mg/kg	-	20	ASTM D5453-93
Variable properties
Contamination	mg/kg	-	25	DIN EN 12662
Acid Value	mg KOH/g	-	2.0	DIN EN ISO 660
Oxidation Stability (110ºC)	h	5.0	-	IS0 6886
Phosphorus Content	mg/kg	-	15	ASTM D3231-99
Ash Content	Mass-%	-	0.01	DIN EN ISO 6245
Water Content	Mass-%	-	0.075	pr EN ISO 12937

Abteilung Technologie nachwachsender Rohstoffe
Arbeitsgruppe Pflanzenöle
Department of Technology, regenerating raw materials
Working Group On Vegetable Oils
Dr. Bernhard Widmann

LTV-Work-Session on Decentral Vegetable Oil Production, Weihenstephan
http://dec2.tec.agrar.tu-muenchen.de/pflanzoel/rkstandard_e.html

The vegetable oil standard

-- comments by Elsbett Technologie
http://www.elsbett.com/engl/vegoil.htm

Density
The kinds of vegetable oil do not differ too much in terms of density. On average density is about 10% higher.

Flash Point by P.-M.
Is much higher than with diesel fuel. Makes transportation and handling much more safe.

Calorific Value
Is nearly equal for all vegetable oils, but 10% less in comparison to diesel fuel. Because of higher density the volumetric content of heat value is about the same.

Kinematic Viscosity
For most vegetable oils higher than diesel fuel. Big differences between the different kinds of seeds. If too high, the oil can’t pass the fuel circuit. Heating is one of the measures to enable engines to run on vegetable oil.

Low temperature behaviour
No specification defined up to now. But the low temperature behaviour is of importance for engine cold start and low load. Viscosity is such an indicator for low temperature behaviour.

Cetane Number
No sufficient testing method existing, because the engines for the standardising tests are all conventional diesel engines. When measured with conventional method, Cetane number is worse, nevertheless practice shows, that ignition delay is shortened in comparison to diesel fuel.

Carbon Residue
There is a remarkable correlation to the residues in the combustion chamber, piston rings and valves, so carbon residue should be kept low.

Iodine Number
Is an indicator for double bindings in the molecular structure. It influences the long time stability of properties (important for storage).

Sulphur Content
Sulphur reduces the function of catalysts and causes SOx emissions like Diesel engines. Normally vegetable oil does not contain sulphur.

Contamination
That is the most important property. It blocks filters and nozzles and is abrasive all over the fuel circuit. Must be well controlled.

Acid Value
Shows the content of free fatty acids. Can effect the properties of lubrication oil if bigger quantities reach the oil sump.

Oxidation Stability
Describes the pre-ageing of the oil. With progressing age the viscosity is also increasing continuously. Can also influence the lubrication-oil.

Phosphorus Content
Is depending much on production method for the oil. Phosphorus is dangerous for the engine due to its abrasive function. When the oil is cold pressed or refined normally the content of phosphorus is within the limits.

Ash Content
Concerns the content of oxide- and raw-ash. Ash is abrasive.

Water Content
If emulgated, a higher water content is not disadvantageous (as long the emulgation remains stable, which is very difficult). Normally water will cause problems anywhere in the fuel system.

Practical experience
Shows that the characteristic properties can anyway not be influenced -- but the variable ones can. So a rough oil quality check should mainly be focussed on:

• Contamination
• Phosphorus Content
• Water Content

Back to: Straight vegetable oil as diesel fuel