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Amount of FSII in fuel

Asked by: 2176 views Aircraft Systems

Fuel system icing inhibitor (FSII) is added to aviation jet fuel to prevent the formation of ice.  I've read that the amount of FSII has been revised from 0.10 % - 0.15 %, down to 0.07 % - 0.10 % by volume.  Regardless, what are the implications if the amount of FSII exceeds the stipulated amount (0.10 % or 0.15 %)?

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1 Answers



  1. Jeffrey A. Baylor on Jan 19, 2014

    What is the proper mixing ratio of PRIST® Hi-Flash™ to AvGas and Jet turbine fuels and why is this important?
    PRIST® Hi-Flash™ Fuel Additive should be mixed properly at the correct ratio of 0.10-0.15% by volume or 1000-1500 PPM. Proper mixing of PRIST® Hi-Flash™ Fuel Additive in to AvGas and turbine Jet fuels is critical to its effectiveness at preventing freezing of suspended water in jet fuel.
    PRIST® Hi-Flash™ Fuel Additive cannot simply be poured or dumped into fuel, as it will coagulate and sink to the bottom. This means the fuel being “splash blended” will have a low concentration and the water in the bottom of the tank will have a high concentration of DiEthylene glycol Monomethyl ether (DiEGME). This may even cause microbial growth to accelerate.

    Improper mixing can also lead to early separation of PRIST® Hi-Flash™ Fuel Additive from suspension in aviation fuels. This can be worsened when an aircraft is stored outside in direct sunlight. The condensation as the tank heats in daylight and cools at night leads to water formation via condensation. The PRIST® Hi-Flash™ Fuel Additive will separate out and settle in the bottom of the tank leaving a very high concentration of PRIST® Hi-Flash™ Fuel Additive in the low points over a period of time.

    The main ingredient in PRIST® Hi-Flash™ Fuel Additive, DiEthylene glycol Monomethyl ether (DiEGME), a strong solvent that can damage fuel bladders and filters in high concentrations. For this reason, we do not recommend

    It may also damage integral tanks and sealants.

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