Fuel system icing inhibitor (FSII) is an additive to aviation fuels that prevents the formation of ice in fuel lines. FSII is sometimes referred to by the registered, genericized trademarkPrist. Jet fuel can contain a small amount of dissolved water that does not appear in droplet form. As an aircraft gains altitude, the temperature drops and the fuel's capacity to hold water is diminished. Dissolved water can separate out and could become a serious problem if it freezes in fuel lines or filters, blocking the flow of fuel and shutting down an engine.
Prior to 1994, Prist was regulated under the MIL-I-27686E standard, which specified use of EGMME, but subsequently came under the MIL-DTL-85470B, with use of less hazardous DEGMME with higher flash point.[2]
FSII was thought to retard the growth of microorganisms eventually present in the fuel, mostly Cladosporium resinae fungi and Pseudomonas aeruginosa bacteria, known as "hydrocarbon utilizing microorganisms" or "HUM bugs", which live in the water-fuel interface of the water droplets, form dark, gel-like mats, and cause microbial corrosion to plastic and rubber parts. But has since been removed from labeling.
EGMME had been certified as a pesticide by the EPA, but as the requirement changes raised the certification costs, DEGMME has no official pesticide certification. DEGMME is a potent solvent, and at high concentrations can damage fuel bladders and filters. Long-term storage of FSII-fuel mixtures is therefore not recommended.
FSII is an agent that is mixed with jet fuel as it is pumped into the aircraft. The mixture of FSII must be between 0.10% and 0.15% by volume for the additive to work correctly, and the FSII must be distributed evenly throughout the fuel. Simply adding FSII after the fuel has been pumped is therefore not sufficient. As aircraft climbs after takeoff, the temperature drops, and any dissolved water will separate out from the fuel. FSII dissolves itself in water preferentially over the jet fuel, where it then serves to depress the freezing point of water to -43 °C. Since the freezing point of jet fuel itself is usually in this region, the formation of ice is now a minimal concern.
Large aircraft do not require FSII as they are usually equipped with electric fuel line heaters or fuel/oil intercoolers that keep the fuel at an appropriate temperature to prevent icing. However, if the fuel heaters are inoperable, the aircraft may be still be declared fit to fly, if FSII is added to the fuel.
Storage and dispensingEdit
It is extremely important to store FSII properly. Drums containing FSII must be kept clean and dry, since the additive is hygroscopic and can absorb water directly from moisture in the air. Since some brands of FSII are highly toxic, a crew member must wear gloves when handling it undiluted. Many FBOs allow FSII injection to be turned on or off so that one fuel truck can service planes that do require FSII as well as planes that don't. Line crew, however, must be able to deliver FSII when it is needed.
fuel, system, icing, inhibitor, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspapers, books, scholar, js. This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Fuel system icing inhibitor news newspapers books scholar JSTOR November 2016 Learn how and when to remove this template message Fuel system icing inhibitor FSII is an additive to aviation fuels that prevents the formation of ice in fuel lines FSII is sometimes referred to by the registered genericized trademark Prist Jet fuel can contain a small amount of dissolved water that does not appear in droplet form As an aircraft gains altitude the temperature drops and the fuel s capacity to hold water is diminished Dissolved water can separate out and could become a serious problem if it freezes in fuel lines or filters blocking the flow of fuel and shutting down an engine Contents 1 Chemical composition 2 Purpose 3 Storage and dispensing 4 ReferencesChemical composition EditChemically FSII is an almost pure 99 9 ethylene glycol monomethyl ether EGMME 2 methoxy ethanol APISOLVE 76 CAS number 109 86 4 or since 1994 diethylene glycol monomethyl ether DEGMME 2 2 methoxy ethoxy ethanol APITOL 120 methyl carbitol CAS number 111 77 3 1 Prior to 1994 Prist was regulated under the MIL I 27686E standard which specified use of EGMME but subsequently came under the MIL DTL 85470B with use of less hazardous DEGMME with higher flash point 2 FSII was thought to retard the growth of microorganisms eventually present in the fuel mostly Cladosporium resinae fungi and Pseudomonas aeruginosa bacteria known as hydrocarbon utilizing microorganisms or HUM bugs which live in the water fuel interface of the water droplets form dark gel like mats and cause microbial corrosion to plastic and rubber parts But has since been removed from labeling EGMME had been certified as a pesticide by the EPA but as the requirement changes raised the certification costs DEGMME has no official pesticide certification DEGMME is a potent solvent and at high concentrations can damage fuel bladders and filters Long term storage of FSII fuel mixtures is therefore not recommended Anhydrous isopropyl alcohol is sometimes used as an alternative Purpose EditFSII is an agent that is mixed with jet fuel as it is pumped into the aircraft The mixture of FSII must be between 0 10 and 0 15 by volume for the additive to work correctly and the FSII must be distributed evenly throughout the fuel Simply adding FSII after the fuel has been pumped is therefore not sufficient As aircraft climbs after takeoff the temperature drops and any dissolved water will separate out from the fuel FSII dissolves itself in water preferentially over the jet fuel where it then serves to depress the freezing point of water to 43 C Since the freezing point of jet fuel itself is usually in this region the formation of ice is now a minimal concern Large aircraft do not require FSII as they are usually equipped with electric fuel line heaters or fuel oil intercoolers that keep the fuel at an appropriate temperature to prevent icing However if the fuel heaters are inoperable the aircraft may be still be declared fit to fly if FSII is added to the fuel Storage and dispensing EditIt is extremely important to store FSII properly Drums containing FSII must be kept clean and dry since the additive is hygroscopic and can absorb water directly from moisture in the air Since some brands of FSII are highly toxic a crew member must wear gloves when handling it undiluted Many FBOs allow FSII injection to be turned on or off so that one fuel truck can service planes that do require FSII as well as planes that don t Line crew however must be able to deliver FSII when it is needed References Edit Advance Petro dead link Professional Grade Paint Products Commercial Paint Thinner Manufacturers Startex Chemicals Retrieved from https en wikipedia org w index php title Fuel system icing inhibitor amp oldid 1152769752, wikipedia, wiki, book, books, library,
