WWII aviation gasoline

Grittis said:

Q: what was the 'British grey pool'? A civilian or military transport service? The US also supplied road tankers for fuel delivery. I can only imagine a 19 yr. old airman with a 45 ft tanker negotiating the country roads at night in E. Anglia...

Geoffrey Sinclair said:

Freeman does not specify where the term grey pool came from, the assumption is civil vehicles painted grey. They were the standard supply method but at times US tankers were needed as well, later came direct pipelines. When it comes to the UK pipelines they were for fuel, not just aviation fuel. The 100/150 fuel was dyed purple, I think 100/130 dyed green as aids to identification.

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I suspect the term came from here:

At midnight on 3/4 September 1939, all the oil companies joined together to form the Petroleum Board. Every petrol station, depot or office, became a Petroleum Board establishment. Around 18,500 staff and every road tanker, barge or rail tanker wagon came under the Board. All the different grades of petrol were done away with and there was one 'pool' grade.

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It would not surprise me if all the road, barge, or rail tankers were repainted a neutral grey to eliminate individual company markings.

Luft.4 said:

I must say likewise, I was talking about iso-octane (explicit once I expanded that thought). Pure toluene is a different chemical so naturally it will have a different rating than iso-octane on the octane scale. "one may not have a fuel that is over 100% iso-octane molecularly. An iso-octane molecule cannot be greater than 100% of itself." Totally agreed that Toluene has a different octane rating than pure iso-ocatane. It is a different chemical after all.

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I commented on your original statement:

Luft.4 said:

A bit of a backgrounder (from a publication I am working on):

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As correctly stated above, there is no 100+ octane fuel moleculary, rather a fuel which performs X% better than pure iso-octance under certain conditions (usually rich mixture).

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Then you changed that into : "one may not have a fuel that is over 100% iso-octane molecularly" which means nothing as that applies to any mixture of any components because in any mixture a single component can never be more than 100 %.

Note also that real gasoline is not simply a mixture of iso-octane and n-heptane. In fact n-heptane is normally not be present at all in gasoline, and it is very well possible to make gasoline without any iso-octane (224TMP) in it.

I showed with a simple calculation example how one can determine the octane number for any component X even when that MON is 100+, but you simply ignore that. BTW: in the same way one can calculate that for some components the MON is below zero.
And once again: that has nothing to do with PN.

Luft.4 said:

Left column, half way into the second last paragraph. "Experiments involving measurements...".
One may not have high temperatures without high pressures. That is why in an engine it is both and why Calumn put an emphasis on both.

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No. Increasing compression ratio in a piston engine automatically means increasing temperature ratio which causes "... drastic overheating, which melted the fragile piston", to finish Calum's sentence which you started.
It's the temperature increase that matters, not the pressure increase. If temperature increases without pressure increase then there will also be risk of detonation if the gasoline MON is too low.

Luft.4 said:

Absolutely, I agree with you there. Compression in a cylinder leads to more pressure which increase the temperature, hence why it is both temperature and pressure. If there were no pressure present in an engine cylinder the burning fuel would never be as reactive if pressure was also present, no matter how high the octane rating is.
All the best,
Dan.

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No, it is as I already mentioned:
A high temperature alone, without a high pressure, will cause auto-ignition.
A high pressure alone, without a high temperature, will not cause auto-ignition.

If in a piston engine the compression would be isothermal (no temperature rise due to extensive cooling) then there would be no risk of detonation.
Note also what don4331 wrote.

FWIW don't know how much this applies to answering the OP question, but re

Q: what was the 'British grey pool'?

from the history of the 'Cornwall Austin Seven Club':

"When WWII was declared the Government introduced petrol supply control under the Pooled Petrol Regulations to be implemented by the Petroleum (Pool) Board. The Board came into being on the 3 September 1939 and became an executive body working under Government direction. Each company's fuel assets, working capital and manpower in the UK was pooled, and each supplier received remuneration, and depreciation, on the assets contributed at agreed rates; whilst the prices, quantity and quality of petroleum products came under Government control. The competitive marketing between the suppliers was stopped and products were supplied by each company in proportion to their pre-war deliveries. All fuels, except lubricants, were sold under a Pool description, the selling price of each Pool product was subject to Government control. Hence, we have the term 'Pool Petrol' which had an approx 74 octane rating."

Note the Austin Seven was a model of car built in the UK from 1923 to 1939. It is considered to be one of the first 'economy' cars built in any numbers in the UK. Apparently, it was popular among motoring clubs due to its simplicity and fuel economy.

I have also been finding mention of the road 'tankers' being painted grey without individual company markings, instead of their normal commercial colours. Various historical models of WWII tanker trucks can be found in the war-time grey livery.

According to one of the BP histories, their tanker trucks in the 1930s were painted green and red, but were overpainted grey during WWII. The petrol rationing and grey paint schemes lasted until sometime in 1950.


From a model railroad history site re the war-time pool petrol tank cars ". . . they were a sort of battleship grey all over with the word Pool in white capital letters at either end of the tank above a red stripe on the centre line."

ThomasP said:

Hence, we have the term 'Pool Petrol' which had an approx 74 octane rating."

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I thought pool petrol was 68 octane? Or is the difference due to the average octane in the pool vs the minimum engines were designed for? Or different measurement protocol? Or do I remember incorrectly?

I have also been finding mention of the road 'tankers' being painted grey without individual company markings, instead of their normal commercial colours. Various historical models of WWII tanker trucks can be found in the war-time grey livery.

According to one of the BP histories, their tanker trucks in the 1930s were painted green and red, but were overpainted grey during WWII. The petrol rationing and grey paint schemes lasted until sometime in 1950.
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From a model railroad history site re the war-time pool petrol tank cars ". . . they were a sort of battleship grey all over with the word Pool in white capital letters at either end of the tank above a red stripe on the centre line."

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Any particular reason why grey was chosen? Was grey paint cheaper at the time, or? Considering there was a war going on, wouldn't it have made sense to paint them green or such to make them harder to spot from the air?

I can not say what the war-time civilian pool petrol ON was. Of note, however, were the many pre-war grades/types of fuel in use in the UK - including a couple types of what we call gasohol today. Before the war the 3 'standard' commercial grades were 68, 75 No. 1, and 80.

The grey colour was selected to eliminate any vestiges of appearance of competition from the fuel parent companies for attracting sales. i think it can be described as psychological in nature, and was to show that everyone was on the same page as far as the war effort goes.

Daggerr said:

as that applies to any mixture of any components because in any mixture a single component can never be more than 100 %.

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So then we both agree with this statement of mine. Why are we talking past each other? I spent 2 posts making this point exactly. Why did I make this point: because there is still some confusion out there (not in this thread) with thinking that a 130 octane fuel is 130% iso-octane. It is not, it simply means a fuel that performs 30% better against knocking than pure iso-octane under certian conditions and measured by certain methods.

Daggerr said:

I showed with a simple calculation example

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And I did not disagree with that statement. Nor did I ignore it. I am in agreement with you here. In fact I wrote this:

Luft.4 said:

Blend a fuel with other fuels (ex add toluene), you are bound to create a new octane rating.

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Daggerr said:

to finish Calum's sentence which you started.

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BTW, glad you found the section! We could also try to take the full sentence in its full context. The word pressure is in the sentence. Pressure assists knocking. Lets not misinterpret Calumn's work here or drop words. That is why in my post #18 I wrote he put an emphasis on both. That is also why in my post # 14 I said I will use both temperature and pressure (should you care to read what I posted).
Let this be the 2nd or 3rd time I explicitly agree with you that temperature is a factor in knocking (again, should you care to read what I posted).
Should you be so caught up with pressure, I would suggest contacting Calumn to mull over his page 25. There is a reason the DVL test method also measures pressure, and that reason is because it has an affect on the fuel's performance.

A lot of times fuel varied. It was too much trouble to blend exactly to 68, or 75 or 80 octane. If they had a batch of fuel that tested to 70 octane do they try to cut it with something to knock it back to 68 or do they try to soup it up to hit 75 or do they just label it as 68 and pour it into the tanks for shipment? And move on to the next batch of 10s of thousands of gallons.

For aviation fuel the specs often said what the upper limits of some things, like lead, could be. Like 4.6cc per US gallon was an upper limit. If refinery X hit the 100/130 performance limits with a batch of fuel that only needed 4.1CCs fine. mix up the batch, retest and ship it and see what the next batch needs.

You don't get exactly the same crude oil even out of adjacent wells in some oil fields. Very close but not exact, now pump a number of wells into one holding tank, repump into tank cars or pipelines, then put it into ships and so one before you even get to the refinery.

As far as the octane 'scale' goes. It stops at 100. there is no 102 or 108 or other number this is despite what gasoline company X says on their pumps/advertising. You can say 100+ or 100 plus or 100>. You compare test fuel to 100 octane reference fuel. if the test fuel will tolerate higher compression in the test engine than the 100 octane reference fuel you can say the fuel being tested is greater than 100 octane. You can not say how much better unless you have a known reference fuel to test against, in the same engine on the same day (or in standard air).
Turned out that the octane scale is not liner. The difference between 99 and 100 is a lot different than the difference between 89 and 90 and both are different than the difference between 79 and 80.

Anybody who wants to argue this can argue with Sam Heron, the inventor/developer of the PN scale and since he died a long time ago........................................

Next problem is trying to figure out how to measure above 100 octane. Some people tried using 100 octane plus 1.0 cc lead and then 2 ccs lead and higher. Trouble is that you get different results from each additional CC of lead (diminishing returns) and you get different results from the same amount of lead in different types/batches of fuel. Cat cracked gas reacts much differently to lead than straight run gas. Two different slopes that actually cross over.
Same with some of the stuff used to boost the knock ratings. It may or may not act in liner fashion. It also may react differently with different base stocks. There can be up to 400 different compounds in gasoline, the vast majority it trace amounts.
But since the Allies allowed up to 20% aromatics in different amounts, in fact the British wanted at least 20% in 1939-40 things get complicated real quick. They knew what they wanted (rich mixture response) but they didn't know how to measure it/specify it. Just specifying equal to reference fuel 100 octane (lab grade) plus 4 CCs of lead wasn't going to actually work.

They had to come up with test procedures for rich mixture response and then get a number of standardized engines (made by Waukesha? ) sent to the test labs in both the refineries, and purchasing agencies and research labs and engine companies so everybody was testing the same thing/s. Not just something close.

^ an excellent point! German C3 was officially 95 octane but most aircraft had 96 painted in the fuel triangle, some even 100!

Luft.4 said:

So then we both agree with this statement of mine. Why are we talking past each other? I spent 2 posts making this point exactly. ........................................ thinking that a 130 octane fuel is 130% iso-octane ...........................

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Your talking about 100 % is irrelevant. Even a child knows that any component in any mixture cannot be more than 100 %.
And I doubt that anybody in the whole world believes that 130 octane fuel is 130% iso-octane.

Luft.4 said:

BTW, glad you found the section! We could also try to take the full sentence in its full context. The word pressure is in the sentence. ...................

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Only that it is measured. That part could have been left out of this sentence as it is not relevant. The subsequently mentioned overheating is caused by temperature.

Luft.4 said:

There is a reason the DVL test method also measures pressure ................

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In every test method anything that can be measured will be measured. It would be foolish not to do so.

Luft.4 said:

Let this be the 2nd or 3rd time I explicitly agree with you that temperature is a factor in knocking (again, should you care to read what I posted).
Should you be so caught up with pressure .............

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Temperature is not just a factor, it is the major factor.
I am definitely not caught up with pressure, it seems you are.

The only reason I commented on your posts is because you mentioned that you are working on a publication.
It seems to me you best put that on hold and spend time on further study of the subject.

Ok Daggerr , we will have to let this one be.

Persistently you fail to read my posts #14, 18, 26 to see that I agree that temperature is a factor as well as pressure, and needed assistance to find the section of interest on page 25 of Calumn's book. It might be best if you read people's comments before replying to them, especially if these have been pointed out multiple times.
I even state I am including temperature in my WIP text (but if one fails to read the post then it is little wonder they cannot recall this).

Thanks for taking to time to write.