Potential Problems of High Efficiency Fuel Filtration and Cold Flow Improver Additives

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IASH 2015, 14th International Symposium on Stability, Handling and Use of Liquid Fuels

Donaldson Company, Inc. | October 2015

Study demonstrating that under certain conditions, cold flow improvers formulated with poly(ethylene-co-vinyl acetate can directly lead to premature fuel filter plugging, and that the use of high efficiency filtration systems exacerbates the problem

  • Cold flow improvers are additives designed to modify the size, shape, and number of wax crystals that form in fuels below their cloud point – additives precipitate at temperatures above fuel’s cloud point and serve as nucleation centers and wax particle growth arresters
  • Study shows that under certain conditions, current commercial cold flow improvers formulated with poly(ethylene-co¬-vinyl acetate)(EVA) can directly lead to premature fuel filter plugging and it is exacerbated by use of high efficiency filtration systems (which capture wax particles that would have passed through older more open filters)
  • 3 major changes in past 15 years have led to adaptations to mechanical and chemical technologies: (1) Increased emissions regulations – dealt with by high-pressure common rail fuel system and exhaust treatment technologies; (2) biodiesel mandates; and (3) ultralow sulfur diesel
    • Fuel injectors in high-pressure common rail engines have significantly tighter clearances compared to previous designs, requiring fuel to be filtered to levels of efficiency never before encountered in fuel applications
      • Typical cleanliness demands for fuel injectors is in range of 12/9/6 per ISO 4406; for an incoming fuel of code 18/16/13, this means fuel filtration must remove up to 99.2% (β=125) of particles ≥4 μm
    • Increased use of biodiesel has added several new chemicals to the fuel (majority are fatty acid methyl esters (FAMEs) and limited amounts of glycerin, alkyl glycerides, sterol glucosides, and fatty acids
    • Hydrotreatment of diesel feedstocks to remove sulfur and other heteroatoms changes combustion, emissions, and lubricity properties of the fuel
  • Combination of unintended precipitation of fuel and additive components along with necessity of high efficiency filtration has led to “perfect storm” causing high occurrence of premature fuel filter plugging
  • Donaldson scientists analyzed hundreds of fuel filters (from all manufacturers, with array of efficiencies and fiber chemistries) that plugged prematurely and found that a few unique chemistries were repetitively identified as the sole reason for an individual acute filter plugging event – this study details the chemistry of how CFI (poly EVA) can precipitate from ULSD and cause premature plugging of high efficiency fuel filters

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