Diesel Fuel Additives ???

[Ross]

Moonsailor, If the temperature of the fuel in

the tank is lower than the dew point all of the moisture in the air will condense on the fuel. More moisture will migrate into the tank via the vent. This process will continue until the latent heat of vaporization warms the fuel to the dew point and the ambient air warms it above the dew point.
The ice box on my boat is quite tight but I have a condensate drain in the bottom and I have been getting copious condensate in the box particularly on the ice jugs. I stoppered the drain with a paper towel wad and reduced the amount of condensate by 80 percent (best guess) and the ice lasts longer. Atmospheric moisture always migrates from the warm side to the cold side. It is very hard to get perfectly dry air. We used to check the dew points for the heat treating furnaces with dry ice and acetone. Dew points of minus 75 degrees F. were about the lowest we could get.

 

[sailaway78]

I have a hard time

with the statements that there is a very small amount of water in saturated air. I have seen too much condensation, in too many different places,virtually running down surfaces to agree with this. I have also had water in the seperator, when the tank has not been touched for a while and it hasn't rained. I realize this isn't very scientific, but it's enough for me to believe you can get condensation in a fuel tank.

 

[Maine Sail]

Experiment..

So I stuck my wifes olive oil dispensing bottle, with vent/ pour spout, into the freezer then after it was chilled to freezer temp stuck it on my deck. Within an hour I had visible condensation on the upper neck of the inside of the bottle..

 

[Big Windy]

Fuel Is Fuel

Fuel is fuel...gas, diesel, jet A...makes no difference if a boat, car airplane, tractor, etc, is sitting in the sun with a partially empty tank, condensation will be there. Bob, Ross, Maine Sail, Nice N Easy, et al are correct...MoonSailer, you sir don't have a clue, get back on your meds!

 

[MoonSailer]

Open versus a closed system

The inside of a fuel tank is connected to the outside by a long thin vent tube. Not much diffusion and the only exchange with outside air is due to small volume changes due to temperature shifts. When a cold object is placed in warm humid air of course there is condensation but this is not a closed system. The air close to the surface is cooled leaves some of it's mositure and is then heavier and sinks. Remember warm moist air is less dense than cold dry air.This air is immediately replaced by more warm humid air. convection currents are set up. Again you can not get convection currents in a fuel tank. If the air in the vent tube gets cooler it sinks into the tank!!!!! Once the tank is full of cold air no more air flow!!!!!! In the morning the tank is full of cold air. NO air exchange except later in the day when the air in the tank warms there is air flow OUT of the tank. In the evening the tank is protected deep inside of the boat. The tank is warmer than the surrounding air ALL NIGHT. As the air in the tank cools cooler drier air is drawn into the tank!!!!! You can argue with the facts but the fact is condensation is not a major source of water in small diesel fuel tanks on sailboats. When the boat is in the water it is even less likely to have condensation form within a tank. At night the tank is probably warmer than the outside air due to the boat being immersed in water. AND again if the tank is colder than the surrounding air there is no air drawn into the tank.

 

[MoonSailer]

Big Windy you are an idiot!!!

You obviously have never compared diesel with gasoline. Pour some diesel around on the ground and hold a flame above but not touching the fuel!!!! Do this first. Now do the same thing with gasoline!!!!! Some people can't understand physics!!!!! I learned this teaching high school physics. Some students could not understand even the basics!!!!!!!!!!!

 

[Maine Sail]

Clearly..

Quote Moon: "The tank is warmer than the surrounding air ALL NIGHT"


Clearly you have spent very little time in the Northern climes. My boats interior temps can fluctuate by 50 degrees or more many times per week. It is not uncommon for it to be 45f during the day, with solar gain on the cover bringing interior boat temps into the mid 50's+, then at night everything on board drops to 20f by morning only to start the cycle all over.

I used to sell a line of residential & commercial oil tanks for a Canadian manufacturer. One of our biggest issues was tank condensation. The standard and rules for tanks finally changed from a side tapping to a bottom tapping to prevent CONDENSATION build up and the eventual freeze and split of oil lines that lead to many oil spills. The new bottom tapings take the water out of the tank and into the inside the house filter so it can't freeze and cause an oil spill.

Of course this change was obviously made by "IDIOT" types because condensation does not occur just as it did not occur in my mini experiment which simulated real world Maine conditions in a boat during the winter..... Cold to warm, cold to warm.

A 275 gallon residential oil tank is no different, other than the scale, than a boats diesel tank and both have a fill and a vent and condensation among residential oil tanks in un-heated garages, under decks etc. have cause many, many condensation, freeze & spill issues.... Trust me I've seen a fair share of 3/8 copper oil lines split wide open from frozen water in the tank due to condensation..

This is why my boats tank is empty in the winter with the vent plugged..

 

[MoonSailer]

How did the water get there????

I have no doubt that water can freeze and bust fuel lines. BUT where did the water come from???? It probably came from the supplier. Again you are compaing uncomparable events. A fuel truck or huge tank pumps hundreds or thousands of gallons at a time. So yes if you pump out a thousand gallons and it is replaced with a thousand gallons of warm moist air you will get some condensation. BUT this is not due to thermal cycling. It is due to filling and emptying large tanks. We are talking about dayly thermal cycling in boats with relatively small tanks. Ross said that his tank is only 10 gallons mine is about 20 gallons. So on a really warm day 227 gallons of warm 100% humidity air contains a few onces of water!!!!! 227 gallons about equals 1 kg of air and at 30 degrees celcius it can hold about 30 grams of water!!!!! About 5% of a coke can . NOT MUCH. so my whole tank on a really hot and humid day might contain 3 grams of water a couple of drops!!!!! Also when I run my engine and the engine compartment and tank warms up..water can move out of my tank!!!!!!

 

[Jim]

Dod anyone hear anything about the new low suffer

diesel? They says it only last 60 days. The machcanic at the marina told me, only buy the the fuel you plan to use. He also said to put the boat away with the tank empty.

What do you hear?

 

[Maine Sail]

Lots of info on condensation out there...

http://www.jamieoil.com/heatingoilservices/oiltank.htm

http://www.sinclairsupply.ca/index.php?page=/_about/inews_art.php?story=inews-04

 

[Ross]

Moonsailor, you have totally missed BigWindy's

point! It makes no difference it you are dealing with gasoline or diesel fuel or number 6 bunker oil. if the fuel temperature is below the dew pointyou will get condensation on the fuel. The surface can be liquid or solid. water vapor is colorless and can not be seen clouds are made of condensate. Rain is condensate. Snow is frozen condensate. The fog on you windows is condensate. If you run you air conditioner too hard on a very hot, humid night you will get condensate on the outside of your windows. If you boil a pot on the stove you create water vapor. If you hold a pan lid over the boiling water you will get condensate. If you hold your bare hand over a pot of boiling water you not only get condensate you also experience the latent heat of vaporization at the rate of 1000 btu's per pound.

 

[Jim]

Sail Maine I have been told it depends on how fast you burn your

fuel. If you don't burn you fuel up fast enough you need to use additives. The best thing for the engine is good fresh fuel without any additives.

 

[Jim]

Here is a link

FYI

 

[Ross]

I googled "storage life of diesel fuel" and got this from BP

at 20 degrees Celcius 12 months is to be expected, at 30 degrees C. 6-12 months is the expected storage life.
This link spells it out in three pages of detail.

 

[Jim]

Ross, good post BUT,

they don't say ultra-low-sulfur diesel (ULSD) in the article. Still 6 - 12 months is not a lot of time for some sailors.

The reason I go interested is my friend Bob doesn't sail that must and his fuels is a coule of years old. He has a lot of crude in his tanks. He took in the the marina to get the filters changed for the second time this year.

When he was talking with the mechanic, he was warned about ULSD and the problems engine manufactures expect.

 

[Jim]

Ross I found this source that say 3 to 6 monts for ULSD

Diesel fuels fare a little better, but not much. Most all diesel fuel, including the EPA's mandated low sulfur version, has shelf life of from 3-to-6 months. Again, this varies widely. Recently we tracked a diesel fuel produced at a refinery in Texas to its final destination in Florida. When tested at the refinery the same day it was produced, the fuel barely met the specification for stability. After being stored, pumped into a coastal tanker, offloaded at Port Everglades, stored again, delivered to the fuel jobber, and finally to the customer, 23 days had passed. Again the fuel was tested. This "fresh" fuel now tested out of "spec."

 

[Ross]

The subject of ULSD needs a lot more study

before I will be willing to comment.

 

[Jim]

Using fuel additives with ULSD fuel...

You also should consider using fuel additives as part of your regular preventive maintenance program. For example, a fully formulated multifunctional detergent designed for ULSD can keep your equipment in shape in seven ways:
1. Cleans up the fuel system and keeps it clean.
2. Protects fuel pumps from wear.
3. Prevents corrosion.
4. Fights acid wear from EGR gases.
5. Removes or displaces water.
6. Reduces filter plugging.
7. Keeps pistons cleaner.

 

[Jim]

Ok Ross,

study up!

 

[Maine Sail]

Jim..

I read your recent link with interest until I got to the end and saw this;

"BY JOHN TARACHA, PRODUCT MANAGER, THE LUBRIZOL CORPORATION"


Please link me to something from an engine manufacturer that says those same things, not a "miracle product" manufacturer who specializes in making "additives", and I'll go right back to using additives in a heart beat.