Cold Soak Method
Update on CEN Methodology
COLD FILTRATION PROPERTIES OF FAME & BIO DIESEL BLENDS
Update on CEN and Canadian Cold Soak Test Methodology applying IP 387 & ASTM D2068 Filter Blocking Tendency Tests
As larger volumes of road transport diesel fuels contain ever increasing percentages of biodiesel, there is a growing need to check that both the biodiesel (FAME - fatty acid methyl ester as specified in EN 14214 and D6751) and the resulting blended fuel meet satisfactory operating criteria and specifications.
Biodiesel (B100/FAME) can contain some substances that are soluble or appear to be soluble at room temperature. These substances, upon cooling to temperatures above cloud point for extended times, can come out of solution and even with the elevation of temperature may not re-solubilise into the product or fuel. This can cause filter blocking when biodiesel, or blends of biodiesel (diesel fuel), are subjected to periods of low temperatures.
In an attempt to improve operability by providing an accelerated means of assessing the propensity of biodiesel or blends of biodiesel to plug filters, ASTM developed D7501. This method cold soaks the fuel and then requires the manual measurement of the time to filter, under vacuum, a volume of the sample.
In Europe the need for a similar, but more automated test method, resulted in the development by the Energy Institute of a cold soak test based on IP 387 Filter Blocking Tendency - published as IP PM-EA. Further work continues to be undertaken by CEN Working Groups to refine the procedures but retain the IP 387 test method as the quantitative finish to the test. Comprehensive European ruggedness trials are planned for August to September 2011.
In Canada the need for a suitable method was more urgent due to the normal extreme climatic conditions. A further cold soak method was developed and tested using ASTM D2068 Filter Blocking Tendency. It has been decided to adopt this cold soak method as a specification test using D2068 as the quantitative finish to the test.
IP 387 and D2068 Filter Blocking Tendency test methods were both recently re-developed in a joint Energy Institute and ASTM programme which resulted in a wider scope, including biofuels, new filters and new precision based on the automated Stanhope-Seta Multi Filtration Tester (MFT).
The Multi Filtration Tester is a unique and versatile automated instrument designed to test fuels including marine and automotive diesel, gas oil, gas turbine fuel, kerosenes and biodiesel. It fully conforms to the latest ‘cold soak’ filterability test requirements for biodiesel and bio diesel blends.