Syphoning fuel

Robisere

Jamie_Carter wrote: »

Apart from it damaging your fuel pump.

Remember diesel lubricates, but petrol can be used to remove oils. Diesel pumps are designed to be lubricated continuously.

Absolutely correct! Many years ago, the garage where I worked as foreman also had a Van Hire outlet. All vans & Mini buses, were Diesel and there were warnings about this printed across the dashboard (right in front of the driver) and around the filler caps (in very large, block cap's) This did not prevent 2 customers filling them with petrol, they were recovered and transported back to us and in both cases my Sundays were ruined when I was called in to rectify an idiot's mistake.

We removed the tank, filters and as much fuel line as we could, washed out and cleaned everything, blew out with (reduced pressure) compressed air, then refilled, started the engine and legged it until the dense white smoke cleared, which it did. A few 'hires' later, the fuel pump packed up, damaged by the petrol as you correctly state.

Forewarned by the first incident, we ordered and fitted a new pump for the second.

vaio

Jamie_Carter wrote: »

1.2 to 8% is actually quite a wide range.......

I suppose that depends on your definition of wide..... 7% where it will burn and 93% when it won't seems a narrow burn range to me

Jamie_Carter wrote: »

.......If the concentration was 100%, then it would be liquid. The vapours would be a mixture of petrol and air.

is 100% vapour actually liquid?

Imagine a fuel tank...petrol vapour is heavier than air so the air will tend to "float" on the petrol vapour and rise to the top of the tank and out through the filler pipe. Once all the air has done that then isn't what is left 100% petrol vapour?

Jamie_Carter

vaio wrote: »

I suppose that depends on your definition of wide..... 7% where it will burn and 93% when it won't seems a narrow burn range to me

It depends on what you are comparing it to. Butane is 1.4% to 9.3%, and propane is 1.7% to 10.9%, but you wouldn't risk striking a match in a cloud of either gas.

vaio wrote: »

is 100% vapour actually liquid?

I suppose that depends if petroleum can actually be a gas.

The way I understand it is that a vapour is air containing molecules of (in this case petrol). If this is the case then for it not to contain air would mean that only petrol molecules remain, and it would be a liquid.

vaio wrote: »

Imagine a fuel tank...petrol vapour is heavier than air so the air will tend to "float" on the petrol vapour and rise to the top of the tank and out through the filler pipe. Once all the air has done that then isn't what is left 100% petrol vapour?

Yes petrol vapour is heavier than air. So at the bottom of the vapour layer it would be above the UEL (upper explosive limit). However at some point where the two layers meet it would be at the IM (ideal mixture), and would therefore be highly explosive in this layer.

vaio

Jamie_Carter wrote: »

........I suppose that depends if petroleum can actually be a gas..........

petrolium can be a gas, I think pretty much anything can be a gas if the temp/pressure are right.

Jamie_Carter wrote: »

........The way I understand it is that a vapour is air containing molecules of (in this case petrol). If this is the case then for it not to contain air would mean that only petrol molecules remain, and it would be a liquid.........

Ahh, the way I understand it is a vapour is a gas containing petrol molecules. If air was present too then it would be a gas containing petrol, oxygen & nitrogen molecules. Over time the heavier petrol molecules would sink to the bottom and the lighter O & N would rise to the top and if there was an escape route (like a filler pipe) then they would escape completely leaving only petrol molecules.

Jamie_Carter wrote: »

.......Yes petrol vapour is heavier than air. So at the bottom of the vapour layer it would be above the UEL (upper explosive limit). However at some point where the two layers meet it would be at the IM (ideal mixture), and would therefore be highly explosive in this layer.

Yep, but in a fuel tank the IM point would be near the filler pipe mouth and well away from fuel pump/sender which I guess is why the news isn't full of "exploding car" stories. None of the pumps/senders I've looked at over the years have been explosion proof in the ATEX/EEx sense

Jamie_Carter

vaio wrote: »

petrolium can be a gas, I think pretty much anything can be a gas if the temp/pressure are right.

But in a non sealed or pressurised container??

vaio wrote: »

Ahh, the way I understand it is a vapour is a gas containing petrol molecules. If air was present too then it would be a gas containing petrol, oxygen & nitrogen molecules. Over time the heavier petrol molecules would sink to the bottom and the lighter O & N would rise to the top and if there was an escape route (like a filler pipe) then they would escape completely leaving only petrol molecules.

That would probably depend on how full the fuel tank is, as well as the temperature.

vaio wrote: »

Yep, but in a fuel tank the IM point would be near the filler pipe mouth and well away from fuel pump/sender which I guess is why the news isn't full of "exploding car" stories. None of the pumps/senders I've looked at over the years have been explosion proof in the ATEX/EEx sense

You have no way of knowing that for sure, and it would depend on a number of factors anyway.

Fuel pumps and senders are intrinsically safe, and won't create a spark in any place that could come into contact with the fuel.

Cars do catch fire due to fuel system faults.

vaio

vaio wrote: »

.......Yep, but in a fuel tank the IM point would be near the filler pipe mouth and well away from fuel pump/sender which I guess is why the news isn't full of "exploding car" stories. None of the pumps/senders I've looked at over the years have been explosion proof in the ATEX/EEx sense

Jamie_Carter wrote: »

........
You have no way of knowing that for sure, and it would depend on a number of factors anyway.

Fuel pumps and senders are intrinsically safe, and won't create a spark in any place that could come into contact with the fuel.

Cars do catch fire due to fuel system faults.

No, pumps and senders aren't intrinsically safe, they are ordinary automotive motors and connectors that wouldn't be allowed anywhere near an intrinsically safe installation.

http://www.carterfueldelivery.com/fuelpumps/_pdfs/support/TEC1608.pdf shows burnt out connectors that live inside the tank and http://www.deatschwerks.com/products/fuel-pumps/dw200-detail shows an in tank pump where the connectors are standard spade connectors on the back of the pump.

Jamie_Carter

vaio wrote: »

No, pumps and senders aren't intrinsically safe, they are ordinary automotive motors and connectors that wouldn't be allowed anywhere near an intrinsically safe installation.

http://www.carterfueldelivery.com/fuelpumps/_pdfs/support/TEC1608.pdf shows burnt out connectors that live inside the tank and http://www.deatschwerks.com/products/fuel-pumps/dw200-detail shows an in tank pump where the connectors are standard spade connectors on the back of the pump.

I don't think you understand what I mean. The parts that are inside the tank are intrinsically safe.

vaio

I don't think you understand what "intrinsically safe" is. http://en.wikipedia.org/wiki/Intrinsic_safety

In tank fuel pumps and their connectors are not intrinsically safe, they can spark and get hot and the reason they don't explode is because the atmosphere in a fuel tank is way way above the explosive/flammable range

Jamie_Carter

vaio wrote: »

I don't think you understand what "intrinsically safe" is. http://en.wikipedia.org/wiki/Intrinsic_safety

In tank fuel pumps and their connectors are not intrinsically safe, they can spark and get hot and the reason they don't explode is because the atmosphere in a fuel tank is way way above the explosive/flammable range

I know exactly what intrinsically safe means.

I know that the connectors aren't intrinsically safe, but these are external to the tank. Any non intrinsically safe parts of the pump are insulated from the inside of the tank. This is why fuel pumps used to all be diaphragm pumps, because they were easiest to separate non intrinsically safe parts from the fuel/vapours.

fivetide

vaio wrote: »

petrolium can be a gas, I think pretty much anything can be a gas if the temp/pressure are right.

Just as an aside, I thought turning petrol into a gas was an essential part of refining oil. Isn't the process called "cracking" as you break the hydrocarbons apart to get the various different products out of it?

Not totally sure. Carry on chaps.