An
illustrated concept of cloud point in biodiesel and how it's determined using ASTM Standard D 2500. In
low temperatures, biodiesel fuels can gel or crystallize, causing fuel filters to plug and fuel lines to clog, which can stop engines.
During low temperature operation, petroleum-based diesel gels at low temperatures, some as low as negative 28 degrees Celsius
whereas biodiesel gels at warmer temperatures like these four hundred times magnified coconut biodiesel crystals growing at 20 degrees Celsius
The Cloud point is the temperature of the fuel at which small solid crystals can be observed as a fuel cools
Feedstocks used to produce the biodiesel affect the cloud point temperature
Soybean Oil Feedstock produces a biodiesel that has a cloud point around one degree Celsius
visible crystals show up in Biodiesel made from Canola oil around zero degrees Celsius
biodiesel made from Jatropha oil begins to crystallize around 8 degrees Celsius
Palm Oil with its high saturated palmitic acid content begins to cloud around 17 degrees Celsius
Biodiesel made from tallow and animal fat can cloud anywhere between 12 and 17 degrees Celsius
Impurities such as free glycerin and monoglycerides and
feedstocks with high fraction of saturates crystallize at higher temperatures and can serve as clouds seed, making the overall cloud point higher
Once the cloud seed is present it is easy for other molecules to agglomerate
Because the molecules go to a lower state of free energy by doing so. This causes visible crystals to form a cloudy appearance
Here it is showing the visible cloud point in biodiesels of various Feedstocks
Blending biodiesel with petroleum diesel and using cold flow additives can improve or reduce the Cloud point by inhibiting
crystal growth by shielding chemical forces
This is the standard testing method for cloud point of petroleum products. Please refer to the ASTM D
2500 before performing tests
Bring sample above 14 degrees Centigrade above expected Cloud point
remove any moisture present by a method such as
filtration through a dry lintless filter paper until the oil is perfectly clear as stated in the standard.
Remove any moisture from testing device
Pour the sample into the test jar to the level mark
Close the test jar tightly by the core carrying the test thermometer
Ensure the thermometer bulb is resting on the bottom of the test jar as stated in the standard
place cork disc in the bottom of the jacket
Place the gasket around the test jar 25 millimeters from the bottom
Place jacket and disc 10 minutes prior to inserting test jar
Maintain the temperature of the cooling bath at zero plus or minus 1.5 degrees Centigrade
this table shows bath and sample temperature ranges
Insert the test jar into the jacket. Never place a jar directly into the cooling medium
At each test thermometer reading that is a multiple of one degree Centigrade
remove the test jar from the Jacket quickly
but without disturbing the specimen
Inspect for cloud and replace in the jacket if the oil does not show a cloud at nine Degrees Centigrade
Transfer the test jar to a jacket in a second bath maintained at negative 18 plus or minus 1.5 degrees Centigrade
Report the cloud point to the nearest 1 degrees centigrade at which any cloud is observed at the bottom of the test jar which is
confirmed by continued cooling
visit our website at www.biodieseleducation.org for more information
The biodiesel education program is sponsored in part by a USDA Grant