Fuel differences (Split from the Oxford Incident thread)

[EGBKFLYER]

Why is that wrong? Avgas is considerably more inflammable than petrol - hence the extra precautions when refuelling. It has a lower flashpoint and autoignition point than car petrol. We were warned of its especially hazardous nature compared with Diesel, petrol and Avtur/ Jet A1 when doing our airfield firefighting course.

[bar shaker]

Why is that wrong? Avgas is considerably more inflammable than petrol - hence the extra precautions when refuelling. It has a lower flashpoint and autoignition point than car petrol. We were warned of its especially hazardous nature compared with Diesel, petrol and Avtur/ Jet A1 when doing our airfield firefighting course.

Then you were taught by someone who knows nothing about fuels. Your instructor probably thought that the higher the octane, the more volatile the fuel. The opposite is actually true.

AvGas vapourises at a higher temp and has a higher flash point. Diesel and AvTur have even higher octane ratings... and guess what ;)

For the purposes of firefighting, I would treat AvGas as the same as Mogas but its no worse.

[EGBKFLYER]

:\ Interesting bar shaker - I shall pass on your comments to the Station Officer when I see him on Sunday. If he has further justification for his view, I'll post it here.

[smarthawke]

2dmoon

I don't want to hijack this thread into a different direction but who mentioned JetA1?!

The fireman claimed that Avgas was much more inflammable than petrol.

[EGBKFLYER]

Thread drift alert! However, our friend on the report makes at least 3 firemen I know of who believe avgas to be more flammable than petrol. Might post a question on Tech Log to see if anyone can come up with a definitive answer... my research so far the morning has confused me, with some saying it's more dangerous and others the opposite! :confused:

[possel]

Why is that wrong? Avgas is considerably more inflammable than petrol - hence the extra precautions when refuelling. It has a lower flashpoint and autoignition point than car petrol. We were warned of its especially hazardous nature compared with Diesel, petrol and Avtur/ Jet A1 when doing our airfield firefighting course.

It is misleading to compare Avgas to petrol, diesel and Avtur in one go - Avgas and petrol are both far more likely to ignite than diesel or avtur.

I think it was Freddie Laker many years ago who challenged someone to stand in a pool of JP4 while Freddie stood in a pool of avtur, and start lighting matches!

[lc_aerobatics]

Re the fuel differences, I have to agree with EGBKFLYER I was always taught that avgas is far more potent/dangerous than Jet A1 (however where Unleaded 95 fits between them all, not too sure)

From another site....

A major problem with gasoline is that it has what is known as a low "flashpoint." This is the temperature at which it produces fumes that can be ignited by an open flame. Gasoline has a flashpoint of around 30 degrees Fahrenheit (-1 degree Celsius). Volatility is a measure of a fuel's ability to evaporate under varying conditions.

The temperature range at which fuel vapor concentrations can be explosive (at ground level in an equilibrium state) are approximately:
1. Avgas 10 to 40 degrees Celsius;
2. Kerosene’s (Avtur, Jet A-1) +38 to +80 degrees Celsius.
3. Wide-cut fuels (JP-4) 20 to +10 degrees Celsius.

Implying easier/more dangerous with Avgas than Jet A1

and if you are mad about fuel, a google search brought this up... Fuel Technologies (http://www.centennialofflight.gov/essay/Evolution_of_Technology/fuel/Tech21.htm)




Ocantan applies to pertol and Avgas
The octane rating is a measure of the autoignition resistance of gasoline (petrol) and other fuels used in spark-ignition internal combustion engines
Higher octane number = higher ingition resistance, so Avgas is harder to ignite then petrol.
.
Lesson ;-

Centan applies to Diesel and Jet A1
What is the Cetane Number...?
The Cetane Number is a measure of the ignition quality of a diesel fuel.
It is often mistaken as a measure of fuel quality.
The Cetane number is actually a measure of a fuel's ignition delay.
This is the time period between the start of injection and start of combustion (ignition) of the fuel.
In a particular diesel engine, higher cetane fuels will have shorter ignition delay periods than lower cetane fuels.
Cetane number should not be considered alone when evaluating diesel fuel quality.
API gravity, BTU content, distillation range, sulfur content, stability and flash point are also very important.
In colder weather, cloud point and low temperature filter plugging point may be critical factors.

[ormus55]

ive thrown lit matches into buckets of diesel (derv) and paraffin. neither set alight.
not tried petrol!

[foxmoth]

ive thrown lit matches into buckets of diesel (derv) and paraffin. neither set alight.
not tried petrol!

Don't try it!

[eyeinthesky]

When I did my fire training for CPL at Redhill, the only easy way to get the Jet A1 to light was to pour avgas on the top of it in a tray (lower SpG) and light that. It ignited straight away, and in time raised the temperature of the Jet A1 enough for it to ignite as well after much fizzing and bubbling. The heat given off by the Jet A1 when it got going seemed far more intense than the Avgas did.

[Mariner9]

:ugh: :ugh:

Take it from me that these are correct:

The flashpoint of Avgas is around -35C
The flashpoint of Mogas is around -40C
The flashpoint of Jet is minimum +38C and typically +38 to +43C
The flashpoint of Motor Diesel is minimum +60C, and typically +65 to +80C
Octane rating and cetane rating have no direct relationship to flashpoint

For all intents and purposes, there is no real difference in the "safety" of Avgas and Mogas, as both readily ignite at normal ambient temperatures:=

[EGBKFLYER]

Cool - another piece of knowledge corrected.

So why do we earth aircraft when refuelling and not cars?

[Mariner9]

So why do we earth aircraft when refuelling and not cars?

Basically, for the same reason we dont have to wear high vis jackets when refuelling cars :E :E

[airborne_artist]

So why do we earth aircraft when refuelling and not cars?

Mogas delivery tankers are earth-bonded before they start to deliver at filling stations.

My guess would be that the amount of static build-up on aircraft is potentially far greater than on cars.

[Sir George Cayley]

Would everyone purleeeeze stop using the word INFLAMMABLE:mad:

The correct form is Flammable = it will burn and
Non flammable = it will not burn.

Think about the prefix in-

inoperative
inadmissable
inaccurate

these all infer the negative which is opposite in the (incorrect) use of that word up there in bold.:ugh:

Rant over:D Feel better:ok:

Carry on chaps I'll fetch me coat

Sir George Cayley

[Final 3 Greens]

Sir George Cayley

You are wrong.

Flammable and Inflammable have the same meaning.

If you don't believe me, try the Oxford Dictionary, see below for extract.....
inflammable

· adj. easily set on fire.
· n. a substance which is easily set on fire.
– DERIVATIVES inflammability n. inflammableness n. inflammably adv.
– USAGE The words inflammable and flammable both mean ‘easily set on fire’. Inflammable is formed using the Latin prefix in- which has the meaning ‘into’ (rather than the more common use of in- to indicate negation), and here has the effect of intensifying the meaning of the word in English.

Are you by any chance one of the people whose recent success in GCSEs (or whatever they are called this year) we are told we need to celebrate? :}

[tangovictor]

ive thrown lit matches into buckets of diesel (derv) and paraffin. neither set alight.
not tried petrol!

some years back I saw a Fire Officer, put a small fire out, during a demo, with diesel, I think it needs very high temps to ignite, or high compression as per in an engine