Water in Fuel

[Skipsta]

Skipsta just answered your questions, the portable tank filler was left loose and covered in plastic to simulate the worst available conditions in a breathable or unsealed tank. Nobody leaves their sealed tanks undone when stored - it was done for demonstration purposes.

Water can come from other sources, I agree, but this should answer your questions of how / why / when condensation forms in unsealed tanks.

I hope this gives you enough technical backup to prove why condensation can be a problem with unsealed tanks.

Regards

Pete

I appreciate the tech stuff Pete

But I think you'll find I always agreed with this theory and my previous post was trying to (very roughly) explain to others why the experiment was done the way it was and how this relates to built in tanks in our boats.

Skipsta

[Mantaray]

skipsta; i don't think there has been any argument that some water is from condensation just that some have the volume of water from this source as all up the creek. if you have large amounts of water all the time then it is more than condensation, if a good filter can't hande it then it is more than condensation

[seatime]

Grand_Marlin,
I'm no chemist and I'm not wanting to correct you but I think you mean boiling off and not evaporating. Some petrols, benzene etc (highly flammable) will start vaporising somewhere around -14 C (not sure but well below 0 C) depending on additives. It is this chemical process which keeps the fuel cool not evaporation.
As you will know diesel requires heating to get to this state.
The end result of water in your fuel is the same still. regards Steve

[Grand_Marlin]

Hey Skipsta....
'tis all cool.... you just interpreted what I said a bit wrong...

More precisely it should have read "Mantaray, Skipsta has answered your questions on the portable tank experiment.........."

You had answered his questions precisely. I made reference to you in my post, as there was no need to add what you had already said to my post.

Cheers

Pete

[Grand_Marlin]

Hi Gelsec,
Unleaded fuel has aditives to stop it from boiling off at STP. Otherwise we would literally have " a tank of gas"
You are correct with the majority of benzene ring based compounds and most hydrocarbons boil off at well below zero degrees - before additives.

Maybe I should have quoted the cooling effect experienced when hydrocarbon based products change state from liquid to gas, instead of evaporation or boiling off.
I chose evaporation to liken it to the cooling of a meat safe for demonstration purposes....
diesel and petrol, will both change state at STP .... but yes, with diesel it happens at a higher temperature.
Diesel needs heating to combust at STP not to change state.
Hence why diesel is less volatile at STP, and requires 3 times more pressure than petrol to combust in a motor.

I answered a question for Mantaray and others as to how and why condensation in a tank occurs, and in particular how the cooling effect works and how dew point is reached. I wasn't exactly providing a chemistry lesson.

I am not picking at you either, but if you disagree with my findings, then please say so.

In theory, diesel should condensate less than unleaded fuel - that I dont have an answer to.

[impulse492f]

[smiley=oops.gif] my oh my oh my impluse you might not have any further comments but i got one for you somebody has just pointed out where you got the above from

http://www.yachtsurvey.com/myth_of_c...fuel_tanks.htm

so why didn't you put the infomation forward impluse [smiley=leer.gif] what not the right outcome

funny I thought that’s where you do your research other peoples websites……, I didn't say I did/did not plagiarise the material.

I drag you in each time, that time you took the rod reel and my arm.

[finga64]

Hey Sahara,

To see if there is a leak or broken seal or somewhere else the water can get in the tank, disconnect the breather hose from the breather and SUCK. When you've sucked all you can slip your tongue on the end of the breather pipe to hold the vacuum. If the vacuum goes there's a leak somewhere if the vacuum stays after about a minute or two it's condensation (your sealing the system with your tongue and negative pressure is evident within the tank by SUCKING). You will not suck up petrol as the breather should be in the top of the tank in the area that should be occupied by vapour alone.

Put a moisture trap of some description in the breather pipe if the vacuum holds. If the vacuum doesn't hold fix the leak.

Personally I couldn't care less about the technical mumbo jumbo and get back to basic analytical thinking and sort the problem out.

My breather is placed in the cowl and I don't seem to have a problem with moisture.

Cheers Scott

[Mantaray]

[quote author=Mantaray link=1139021238/120#133 date=1139810106]

[smiley=oops.gif] my oh my oh my impluse you might not have any further comments but i got one for you somebody has just pointed out where you got the above from

http://www.yachtsurvey.com/myth_of_c...fuel_tanks.htm

so why didn't you put the infomation forward impluse [smiley=leer.gif] what not the right outcome

funny I thought that’s where you do your research other peoples websites……, I didn't say I did/did not plagiarise the material. :-
I drag you in each time, that time you took the rod reel and my arm.
[/quote]


plagarise? what's that got to do with anything?

so why didn't YOU post the infomation?

looks extremely relevent to the discussion, don't you think

[Mantaray]

out of curiosity? does everybody draw from the top of the tank or out through a bottom fitting?

[HarryO]

Holy H20, Batman...

Yes....I had a lovely weekend,.... Thanks for asking.

Harry...

[finga64]

out of curiosity? does everybody draw from the top of the tank or out through a bottom fitting?

Does it really matter. All the difference is if it's from the bottom you have troubles all the time and if it's drawn from the top you have troubles when the tank gets down a bit. That's usually towards the end of the day when everyones tired and cranky.

There's 10 pages trying to fix a relatively simple problem and it's turned into a debate on technicalities and who can do a Google search the best. Poor bugger is probably very confused by now and if my memory serves correct THIS THREAD HAS PUT A BLOKE OFF BUYING A BOAT ALL TOGETHER. That's pretty bad in my books.

The problem is water in the fuel:- (a) find where the water is getting in.
(b) stop the water getting in.
(c) if there are intermittent /slight problems with water in fuel bung a water seperator/filter on. Who cares which one is better then the other. If I was looking for a filter i'd ask what it did compared to the rest and how much a replacement element is. Simple.

Flow rates-who cares. The majority of engines used on the oridinary run of the mill boats that most of us will use DO NOT use 60l/hour. Simple. Huge flow rates are not required. There, saved another 2or3 pages on this thread.

How about trying to help this poor bugger not mudslinging or trying to show who knows more??

[seatime]

Hey Grand_Marlin
No not picking, just a friendly tech correction before you got an unfriendly one. It would be good to solve the water issue though, as it is a common problem, insulating might work, a smaller diameter and longer breather pipe maybe, water trap intank, sophisticated water/fuel interface equipment (water finding paste on a stick). cheers

[Mr__Bean]

.

if you have large amounts of water all the time then it is more than condensation

Well, get ready for it everyone.........



Here it comes..........



Mantaray, I agree with you on this bit. I don't think "large" amounts of water regularly pulled from tanks is due to condensation.


Phew.... wasn't as hard as I thought...........

I don't discount that condensation is an issue for many of us however, and I do feel strongly that it needs to be managed.

Be aware where your breather is in relation to humidity sources, is it sucking air from beneath a cover or is it out in the clear air when stored, is the boat being stored wet, or let to dry before storing in the closed shed.

These conditions are worthy of our attention I believe in our defence against water induction to the fuel.

Anyway, after a couple of days of interesting jousting, that's my last 2 bobs worth.

Take it or leave it...... but please consider it.

- Darren

[Mantaray]

[quote author=Mantaray link=1139021238/135#143 date=1139821924]out of curiosity? does everybody draw from the top of the tank or out through a bottom fitting?

Does it really matter. All the difference is if it's from the bottom you have troubles all the time and if it's drawn from the top you have troubles when the tank gets down a bit. That's usually towards the end of the day when everyones tired and cranky.
[/quote]

what i was trying to say finga was that i have seen many many underfloor tanks where people have put the outlet right in the bottom/side of the tank instead of one of those fitting things which does not go all the way to the bottom fro the top so would it matter if it was first up or at the end of the day any water is still on the bottom and any that gets stired up is handled by the filter/separator? any outlet direct from the bottom of the tank simply has to feed any water in one foul gulp?

in any case you still have to get the water from somewhere and this i suppose is what all this is about, the myth or the magic

so yes i do think it matters where the outlet is!

[Mantaray]

bean we crossed paths there.

yes every little bit counts and i do believe that people should take specific notice of a lot of things, breathers, fillers, take off points, fuel senders, what else? must be something? maybe keep the kids away from the wash down hose. hey dad? what's this 2 eyed thing i'm spraying the hose in

my last comment also i think the point's been made, more than condensation