What happens to fuel when it freezes???
Flying the polar routes from the USA, hence refuelled with Jet A, we have the ACTUAL fuel freeze temperature tested for the fuel uplift. This is done by analyising three samples. One at the start of refuelling, one half way through and one at the end. It cost a bundle I believe but the results are quite useful. The worst freeze temp I have been given for Jet A (generic FP -40C) was -45.6C.
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Icing.
So the stuff they spray into the Lear during refuelling is that for preventing an ice build up or prevent the gel from forming. The old Citation used the same procedure.
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Why you should use a fuel additive
All turbine aircraft fuels contain some dissolved water. It cannot be extracted because it does not exist as particulate water. When an aircraft rises to flight altitude, the fuel cools and its capacity to retain dissolved water is reduced. Some of the dissolved water separates out as discrete water that can form into ice crystals or remain as a supercooled liquid. When supercooled water strikes a tubing bend or a filter, it can freeze quickly and block a fuel line or filter. If suspended ice crystals are present, they can also block a filter. Prist Hi-Flash anti-icing aviation fuel additive controls icing in aircraft fuel by depressing the freezing point of water.
Controlling Fuel System Icing
Prist Hi-Flash additive has limited solubility in jet fuel, but is completely soluble in water. When dissolved water separates from the fuel, some amount of Prist Hi-Flash additive quickly leaves the fuel and preferentially dissolves in the water. This depresses the water's freezing point. As the fuel gets colder, and more water particles appear, more Prist Hi-Flash additive leaves the fuel and enters the water, and your aircraft's fuel lines stay clear.
All turbine aircraft fuels contain some dissolved water. It cannot be extracted because it does not exist as particulate water. When an aircraft rises to flight altitude, the fuel cools and its capacity to retain dissolved water is reduced. Some of the dissolved water separates out as discrete water that can form into ice crystals or remain as a supercooled liquid. When supercooled water strikes a tubing bend or a filter, it can freeze quickly and block a fuel line or filter. If suspended ice crystals are present, they can also block a filter. Prist Hi-Flash anti-icing aviation fuel additive controls icing in aircraft fuel by depressing the freezing point of water.
Controlling Fuel System Icing
Prist Hi-Flash additive has limited solubility in jet fuel, but is completely soluble in water. When dissolved water separates from the fuel, some amount of Prist Hi-Flash additive quickly leaves the fuel and preferentially dissolves in the water. This depresses the water's freezing point. As the fuel gets colder, and more water particles appear, more Prist Hi-Flash additive leaves the fuel and enters the water, and your aircraft's fuel lines stay clear.
This is a separate issue from the actual jet fuel freezing.
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Water Content.
Just looking at some Stats:
AVTUR – Freezing point -47C
Aviation Turbine Kerosene AVTUR- Freezing-50C
JET A- Freezing point -47C
I am told the fuel temp at high altitude drops to the minus 20’s, so why does one fuel need PRIST and the other not? Surely all fuels contain some dissolved water including JET A.
AVTUR – Freezing point -47C
Aviation Turbine Kerosene AVTUR- Freezing-50C
JET A- Freezing point -47C
I am told the fuel temp at high altitude drops to the minus 20’s, so why does one fuel need PRIST and the other not? Surely all fuels contain some dissolved water including JET A.
