Cold Soak Session Powerpoint

COLD SOAK FILTRATION TEST ASTM D6751-08

Mandatory Annex

ASTM D6751-08 Mandatory Annex

• Cold Soak Filtration became part of the Biodiesel Fuel Blend Stock (B100) specifications effective October 13,2008.

History of the Method • Cloud point (CP) has been determined to be an accurate if not conservative indicator of a fuels Estimated Minimum Operating Temperature (EMOT)

• During winter months in cold climates, Diesel fuel is formulated to have a lower cloud point.

History of the Method • Biodiesel typically has cloud points ranging from -5C to 20C depending on feedstock

• The blending of B100 into Diesel fuel will typically raise the CP.

• Final blend CP should still be an indicator of the Estimated Minimum Operating Temperature.

History of the Method • During the winter of 2005/2006 there were a

significant amount of fuel filter plugging issues for consumers using Biodiesel blends.

• During the winter of 2006/2007, a version of the Cold Soak Filtration test was implemented in Minnesota, which seemed to identify B100 that can affect low temperature operability.

Why was the Method Developed? • Some B100 can form precipitate at temperatures above CP

• The search was on for a test that could identify B100, that in blends up to B20, shows precipitation and fuel filter plugging above the CP

Why was the Method Developed?

Watch Video

What Are Industry Concerns? • What were the impurities that were the cause of the filter plugging?

• Potential culprits:

– Monoglycerides – Soap – Water – Sterol Glucosides (plant sterols) ADM study seems to show a combination effect

• Both the National Biodiesel Board (NBB) and National Renewable Energy Laboratory (NREL) have indicated that the, “typical sample will either pass, or fail miserably.”

• They have further indicated that this largely depends on the manufacturing processes.

Method Concerns • Published interim precision:

200s 360s 61.0 – Repeatability 34.0 – Reproducibility 115.9 208.1

• Lab-to-lab reproducibility will become the focus of critical attention.

• The following points refer to sections of the method and require consideration:

• A1.6.1.1 • Funnel and Filter Base with a stainless steel filter support. The sintered glass support has been shown to give much higher filtration times and should not be used. USE ONLY THE SS FILTER SUPPORT!

• A1.6.2.4 • Glass Fiber Filters, plain, 47mm diameter, nominal pore size 0.7um.

Intertek uses a standardized filter in an attempt to reduce variables: Whatman GFF 47mm Circles, Part No 1825-047, Fisher 09-874-71

• Sampling A1.9 • DO NOT skip over the "Sampling" section assuming it contains nothing of importance from a laboratory perspective! It does!

Sample Container A1.9.1 to A1.9.3 • Recommended sample container for this test is a 500ml bottle. Use of this container might not be logistically possible, so other container sizes are permissible. • Sample size must be at least 300ml. An individual sample for CSFT should be obtained. Samples must be protected from sunlight, amber bottles are preferred. This test may require sample preparation prior to withdrawing any portion from the bottle. Typically, other tests are performed on the product, so additional samples should be available. For example, if a D6751 or EN14214 slate is requested, typically four individual amber quart/litre boston round bottle samples will be obtained. If U,M,L level samples are required to be composited, an additional set should be taken for the cold soak sample preparation.

A1.9.3.1 • It should be known that performing the CSFT

preparation on the sample portion designated for additional analysis may alter parameters such as Oxidation Stability, Cetane Number, Methanol content, Flash point and others.

• If the sample may have been <20C, “thermal memory removal” must be performed before transfering any portion of sample.

A1.9.4 through A1.9.5 These sections may be considered confusing and possibly out of sequence.

• Only in warmer climates or the middle of summer

will it be safe to acknowledge that the sample has never been exposed to temperatures below 20°C, (assuming sample is of local origin.). It is also unlikely that the lab will receive 300ml of sample in a 500ml bottle.

A1.9.4.1 Sample Preparation • Heat the designated CSFT sample to 40°C for at

least 3 hours under an inert atmosphere to erase any thermal history and to dissolve any solids that might have precipitated during transit. This preparation is not necessary if it can be clearly demonstrated that the sample has never been exposed to temperatures below 20°C. If this is verified then the test can proceed directly to A1.9.5.

A1.9.4.2 • After heating for the required time, allow the

sample to sit for at least 24 hrs at a temperature no lower than 20°C. The 24 hrs is a significant change to this method. If using ambient air, assure your lab temperature does not fall below 20°C during the cooling period.

A1.9.5 • Shake the sample vigorously for 1 minute, measure

300ml and transfer to a clean fresh 500ml bottle. A clear bottle is recommended at this point so that the sample can be easily inspected for the presence of visual solids. It is mandatory to pour off 300ml to a fresh 500ml bottle at this point, regardless of how the sample was handled in previous steps. The actual analysis is performed on this 300ml sample portion in a 500ml bottle.

A1.11.2 • After the16hs cold soak is completed, allow the sample

to come back to room temperature (20-22°C) on its own without external heating. Filter the sample within 1hr after reaching 20-22°C.

• The NBB stated, "no external heating above room

temperature, can be interpreted to mean a room temp water bath".

A1.11.4 • This section contains sequence errors. Applying vacuum to a dry filter paper will not allow the operator to set the pressure. Start the vacuum and set target conditions to achieve 21-25 in. Hg below atmospheric pressure when the sample is introduced. The adjustment and recording of vacuum pressure is handled in A1.11.6.

A1.11.6 •

Immediately after swirling, pour the entire contents of the sample container into the filtration funnel and simultaneously start the timer. Start the timer immediately the B100 contacts the filter under vacuum. The vacuum pressure shall be between 21-25 in. Hg below atmospheric pressure, if not make adjustments. After one minute, record the vacuum pressure. 21-25 in. Hg below atmospheric pressure is a fairly wide range. Higher vacuum pressure could decrease filtration time. In order to provide process standardization, set the vacuum pressure in the middle range, ~23 in. Hg below atmospheric pressure, and maintain using a needle valve for the duration of the timing.

Results • Record the Filtration Time (FT) from the point where the sample hits the filter until the point that the filter is visibly free of liquid sitting on top of it.

• If FT is >720s (12min), record final pressure, stop the test, and record sample amount that had been filtered.

Test Demonstration