Syphoning fuel

vaio

Jamie_Carter wrote: »

I know exactly what intrinsically safe means......

Obviously not otherwise you wouldn't be suggesting that a pump which can consume 10A at 12V (so 120W) could ever comply with the allowable power that IS mandates (typically an absolute maximum of 1.2W).

You aren't going to pump anything with only 1.2W of power

Jamie_Carter wrote: »

.....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.

Fuel pumps used to be diaphragm because they were cheap and simple to make, particularly when mechanically driven, nothing to do with IS and I don't ever remember seeing a diaphragm "in tank" pump. EFI needs much higher pressures than diaphragm pumps can produce hence the move to vane/gear pumps.

As for there being no connections within the tank, all I can do is refer you to the links given in my previous post

vaio wrote: »

.......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: »

Obviously not otherwise you wouldn't be suggesting that a pump which can consume 10A at 12V (so 120W) could ever comply with the allowable power that IS mandates (typically an absolute maximum of 1.2W).

You really don't understand limits of flammability, and the requirement for intrinsically safe components do you?

Do you really think that petrol pumps in filling stations, or oil refineries only operate on 1.2W do you?

If what you said was true, then a petrol tank with only a small amount of fuel, at very low temperatures would have an atmosphere within the limits of flammability. And there would be loads of cars bursting into flames.

Due to insulation making all internal fuel tank components intrinsically safe, the only source of ignition would be when there is a failure in the insulation. But under normal circumstances there are no components within a petrol tank that can cause ignition.

vaio

Jamie_Carter wrote: »

You really don't understand limits of flammability, and the requirement for intrinsically safe components do you?.....

LEL & UEL aren't rocket science and whilst I only occasionally work with IS components in my dayjob I do know the definition of intrinsically safe......“a type of protection based on the restriction of electrical energy within apparatus and of interconnecting wiring exposed to the potentially explosive atmosphere to a level below that which can cause ignition by either sparking or heating effects”

I also know that the maximum available power is <1.2W rather than the 120W that a pump can draw.

Jamie_Carter wrote: »

.....Do you really think that petrol pumps in filling stations, or oil refineries only operate on 1.2W do you?....

Nope, but then those pumps aren't intrinsically safe, they would be ATEX EEXd explosion proof or similar.

Jamie_Carter wrote: »

.....If what you said was true, then a petrol tank with only a small amount of fuel, at very low temperatures would have an atmosphere within the limits of flammability. And there would be loads of cars bursting into flames......

Temperature or amount of fuel (as long as there was enough to fill the tank with vapour) doesn't affect the relative molecular weight of petrol vapour & oxygen molecules which is what keeps the inside of a tank well above the UEL

Jamie_Carter wrote: »

.....Due to insulation making all internal fuel tank components intrinsically safe, the only source of ignition would be when there is a failure in the insulation. But under normal circumstances there are no components within a petrol tank that can cause ignition.

As above, IS is nothing to do with insulation, it's to do with limiting energy. Short IS wires together and the spark produced isn't strong enough to ignite anything (or pump anything).

But really it matters not because automotive fuel pumps aren’t IS, neither are the in tank connectors and the reason cars don't explode on a daily basis when pumps spark or connectors burn is that the atmosphere in the tank is above the UEL and no amount of gum flapping from me or you is going to change that.

If you still disagree and choose to carry on ignoring the links showing burnt out in tank connectors etc than I guess there is nothing else I can do so I’ll leave you to it

Avoriaz

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.

I doubt that fuel pumps would be affected.

Diesel with a few percent added petrol will still lubricate the fuel pump etc. Any solvent effect of the petrol will be absorbed or masked by the diesel.

Years ago some drivers put up to 15% petrol in diesel tanks to aid cold weather starting, and in some colder parts truck drivers put a little in to stop the diesel solidifying. That is less necessary now as modern diesel is developed to be less prone to waxing or solidifying.

Maybe modern cars might be more prone to being damaged by petrol in diesel but it is all a bit academic. As I wrote above, I wouldn't bother with all the effort for a small saving.

westwood68

Avoriaz wrote: »

I doubt that fuel pumps would be affected.

Diesel with a few percent added petrol will still lubricate the fuel pump etc. Any solvent effect of the petrol will be absorbed or masked by the diesel.

Years ago some drivers put up to 15% petrol in diesel tanks to aid cold weather starting, and in some colder parts truck drivers put a little in to stop the diesel solidifying. That is less necessary now as modern diesel is developed to be less prone to waxing or solidifying.

Maybe modern cars might be more prone to being damaged by petrol in diesel but it is all a bit academic. As I wrote above, I wouldn't bother with all the effort for a small saving.

Perfectly correct for older pumps. I regularly hit 15% petrol mixed with veg oil during the very depths of winter. 11,000 miles in this car and about 30,000 in other cars. All powered by older mechanical Bosch fuel pumps which are unbelievably robust. I wouldn't expect a newer pump to last at the same percentages.

Indeed, the W124 handbook for my old Merc actually advised adding up to 20% petrol in winter to prevent gelling.

Jamie_Carter

vaio wrote: »

LEL & UEL aren't rocket science and whilst I only occasionally work with IS components in my dayjob I do know the definition of intrinsically safe......“a type of protection based on the restriction of electrical energy within apparatus and of interconnecting wiring exposed to the potentially explosive atmosphere to a level below that which can cause ignition by either sparking or heating effects”

I also know that the maximum available power is <1.2W rather than the 120W that a pump can draw.



Nope, but then those pumps aren't intrinsically safe, they would be ATEX EEXd explosion proof or similar.



Temperature or amount of fuel (as long as there was enough to fill the tank with vapour) doesn't affect the relative molecular weight of petrol vapour & oxygen molecules which is what keeps the inside of a tank well above the UEL



As above, IS is nothing to do with insulation, it's to do with limiting energy. Short IS wires together and the spark produced isn't strong enough to ignite anything (or pump anything).

But really it matters not because automotive fuel pumps aren’t IS, neither are the in tank connectors and the reason cars don't explode on a daily basis when pumps spark or connectors burn is that the atmosphere in the tank is above the UEL and no amount of gum flapping from me or you is going to change that.

If you still disagree and choose to carry on ignoring the links showing burnt out in tank connectors etc than I guess there is nothing else I can do so I’ll leave you to it

What a load of rubbish.

I also use intrinsically safe equipment in my profession. And as an example the two way radios are not regarded as intrinsically safe if any of the insulation is damaged in any way.

Jamie_Carter

Avoriaz wrote: »

I doubt that fuel pumps would be affected.

Diesel with a few percent added petrol will still lubricate the fuel pump etc. Any solvent effect of the petrol will be absorbed or masked by the diesel.

Years ago some drivers put up to 15% petrol in diesel tanks to aid cold weather starting, and in some colder parts truck drivers put a little in to stop the diesel solidifying. That is less necessary now as modern diesel is developed to be less prone to waxing or solidifying.

Maybe modern cars might be more prone to being damaged by petrol in diesel but it is all a bit academic. As I wrote above, I wouldn't bother with all the effort for a small saving.

Modern diesel pumps run at much higher pressures, and are damaged by even 15% petrol.

vaio

Interesting picture of the connectors on a Jeep in tank pump where the connection had been arcing so badly and for so long it had burnt away half the terminal.

http://www.jeepforum.com/forum/f12/spark-gas-tank-1337953/

Jamie_Carter

vaio wrote: »

Interesting picture of the connectors on a Jeep in tank pump where the connection had been arcing so badly and for so long it had burnt away half the terminal.

http://www.jeepforum.com/forum/f12/spark-gas-tank-1337953/

And are those terminals internal or external to the fuel tank?

vaio

I know you aren't a great one for following links so I'll quote the relevant bit from the jeepforum thread

....This is the negative lead to the fuel pump which has obviously been arcing for a long long time to get this much decay on the terminal.

It scares me to think that there has been sparking in the gas tank. Holly crap!

Obviously it hasn't caused an explosion or anything but it makes me wonder if there is really a danger or not.....

I'm guessing that the bit about being scared because of "the sparking in the fuel tank" tells you the damaged terminal is inside the tank (as they are on many (most?) cars