ALS Tribology eSource
November 2010

Fuel ImageNew Automated CFPP Instrument Now Used at ALS Tribology's Sparks, Nevada, Laboratory
by Ambrose Hughey, OMA I, Laboratory Manager
Sparks, Nevada, and Portland, Oregon

ALS Tribology expands its fuel testing services with the addition of a new, automated cold filter plugging point (CFPP) instrument at our Sparks, Nevada, laboratory. The recently purchased instrument uses rapid cooling conditions during which 20 milliliters of fuel is drawn through a 45-micron screen and then is allowed to flow back through the screen again for further cooling. This process is continued every 1°C until either the 20 milliliters of fuel fails to be drawn through the screen (plugs the filter) in 60 seconds or it fails to return through the screen in 60 seconds.

The CFPP provides an indication of the low temperature operability of fuel. Low temperature operability is an issue with middle distillate fuels because they contain straight and branched chain hydrocarbons (paraffin waxes) that precipitate, causing wax formation at cooler temperatures. Wax formation can also be exacerbated by blends of biodiesel fuel with conventional diesel fuel. Wax may plug the fuel filter or completely gel the fuel, making it impossible for the fuel system to deliver fuel to the engine.

Generally, additives used to improve low temperature operability do not mitigate the formation of wax; however, the additives employed modify the wax's size, shape, and/or degree of agglomeration—resulting in improved low temperature operability. Use of CFPP analysis aid in estimating the low temperature operability of the fuel and in monitoring the performance of any cold flow improver additives.

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