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Anonymous Poster #1

Water Solubility in Fuel Conversion

08/17/2012 12:14 AM

Sir,

Could you tell me how to read the below graph of water solubility Vs temperature of fuel (Jet A1). I want the value for, in 1 m3 of fuel how much water can be there in dissolved form. And for a temperature reduction of 10°C how much water (in m3) will come out from a fuel of 1 m3 volume.

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#1

Re: water solubility in fuel-conversion

08/17/2012 1:29 AM

Use the graph to find the water solubility at the two temperatures.
Multiply the solubility by the total volume in each case, to get the water volume.
Subtract.

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Re: Water Solubility in Fuel Conversion

08/17/2012 10:18 AM

Jet A1 is a mixture of two hydrocarbon liquids distilled from crude oil. These liquids or "cuts" are kerosene and naphtha. There are slight differences in these cuts depending on the temperatures of the distillation process and the crudes used. The cuts are within a specific range and therfore are not one fixed density. Jet A1 is therefore not a fixed density either but within an allowable range. In summer Jet A1 is a 50/50 mix of these two liquids and in winter the naphtha proportion is increased by about 5% to allow for the lower temperatures encountered. ASTM Jet A1 Specification. ... we also used to add anti static and an anti icing additives. These are very small amounts and will have little impact on the overall SG. If there is any water present, which there should not be, the Jet A1 will be a "milky white" colour. If the Jet A1 is sold as heating oil it is known as paraffin oil. This product has a dye added to it to distinguish it from Aviation quality Jet A1. The dye is usually pink or blue depending on the company selling it. (e.g. In the UK these products were sold as Aladin Pink or Esso Blue paraffin oil.) Other than the colour paraffin oil is Jet A1. .. the result is that there is not a simple constant you can apply to temperature to give you density...

"It is very important that jet fuel be free from water contamination. During flight, the temperature of the fuel in the tanks decreases, due to the low temperatures in the upper atmosphere. This causes precipitation of the dissolved water from the fuel. The separated water then drops to the bottom of the tank, because it is denser than the fuel. From this time on, as the water is no longer in solution, it can freeze, blocking fuel inlet pipes. This was the cause of the British Airways Flight 38 accident. Removing all water from fuel is impractical, therefore fuel heaters are usually used on commercial aircraft to prevent water in fuel from freezing.

There are several methods for detecting water in jet fuel. A visual check may detect high concentrations of suspended water, as this will cause the fuel to become hazy in appearance. An industry standard chemical test for the detection of free water in jet fuel uses a water-sensitive filter pad that turns green if the fuel exceeds the specification limit of 30ppm (parts per million) free water."

http://www.pprune.org/tech-log/348739-temperature-vs-fuel-density.html

http://en.wikipedia.org/wiki/Jet_fuel#Water_in_jet_fuel

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