Fuel Tank Vent Filter

[trlrtrsh]

Recently I have seen a couple advertisements for Fuel tank filters that are designed to remove condensation before it gets into the fuel. They claim that most fuel problems are from water intrusion and that contributes/promotes growth of bad stuff. Supposedly most water enters with temperature change, and raising/lowering the fuel level which creates a low pressure and humidity increases.
Has anyone tried these filters. I went to the web site of one company, and the filters are very simple. They install in the vent line, and are full of a dessicant, purple or blue when they are good, turn pink when they need serviced.
They sound good to me, but a bit pricey for what they are.
Would be interested if anyone has experience with them.

[pdqaltair]

Please give details. There are several types and I don't know what you mean. Those used on vehicals are not apropriate; they are carbon canisters to control gasoline emmisions and are intended to be flushed by the operation of the car each day. They would not be very effective on a boat. Additionally, the instalation must not compromise the vent system of the tank (bypass venting is needed).

But we're interested!

[arf145]

Recent stuff I have read suggests that water from condensation in the tank is not near as common or significant as folks think. The real source of water intrusion is from the fuel pump source itself or from leaks in the gasket around your filler cap.

[pdqaltair]

Originally Posted by arf145

Recent stuff I have read suggests that water from condensation in the tank is not near as common or significant as folks think. The real source of water intrusion is from the fuel pump source itself or from leaks in the gasket around your filler cap.

Very true, certainly true for diesel.

However, e-10 contains ethanol and can readily absorb water from the air without condensation. Most probably this thread is of no interest (other than your comment) to diesel operators.

Having spent much time with this issue (I am in the gasoline recycling business) I would venture 90-95% of e-10 problems are also due to leaks, as you suggest. However, if a tank is left part-full for a long time in a humid place... well, the dialog is interesting. The following blog post refferences a number of information sources:
Sail Delmarva: Ethanol and Gasoline and Diesel - References

And this one, just for fun:
Sail Delmarva: E-15 Approved by EPA for 2007 and Newer Vehicals

[trlrtrsh]

pdqaltair, Thanks for your comments and response. To be clear, I am not discussing E-15, as it is still under scrutiny for Marine Use, both Gas and deisel. I am not referring to existing problems, crimped line, deteroriated gaskets, etc. as I currently have no current problems with the fuel delivery on my boat.
What I am asking about are the advertised filters/dehydrators being offered. They do put a compelling argument for the need for them out there. As I stated in my original post, they are filled with dessicant that when activated turns pink in color. When I was in the military I was charged with the same type of dehydrators (in theory), they were filled with cat litter type desicant and the blue/pink crystals were for indication of reaching their servicability, and were removed and heated air passed over the desicant till it returned to blue color. This was a protectant for avionics equipment. My question was simply "Has anyone tried this." "If so, your opinions, worth it or not etc."
I am a fairly new boat owner, And am looking forward to positive feed back.
I see a lot of advertising for fuel scrubbing, tank polishing, water seperators clogging. If this simple filter/dehydrator works, then I will try to install one in my boat. I would just like to know if anyone has had experience with them.

[RichH]

Ive been using a large desiccant trap on my boats since the late 1980s. I used to engineer 'dehydration systems' a long time ago.

There are a few problems that should be noted.
The most common desiccant is simple silica gel. You can obtain 'dyed' Si-Gel which when saturated with WATER VAPOR turns from blue to pink. However most desiccants will 'saturate' not as an 'average' but as a 'frontal zone', the zone 'front' will be saturated (pink) on one side and 'desaturated' (blue) on the other side of the front (called an isotere). The problem is that unless you see or monitor the movement of the 'front' you can easily become saturated and then 'break-through' with totally saturated water vapor .... to see you need a 'clear or translucent' chamber - and that isnt going to be 'fire-proof'.
The other problem is that the desiccant will also aDsorb oil vapor from the 'reverse side' and there is no indicator dye for oil vapor .... so you really need two chambers - one with a silica gel or activated alumina for water aDsorption and a separate chamber filled with charcoal granules to 'protect' the desiccant chamber. .... a wee bit 'complicated' to do the 'correct' job.

Other problems
Silica gel will fracture into a 'dust' if in contact with liquid water ... and the 'dust' will easily 'compact' and will stop the flow of air; so, you really need a vacuum rupture disc installed to prevent 'imploding' the tank by excess vacuum if for 'some' reason the silica gel becomes 'powder'.
Desiccants can be regenerated ..... put into an oven and heat at 350 deg. for 6-8 hours - but any oil vapor that is co=adsorbed will turn to 'coke' (thats why you also need the carbon (bed/chamber) between the tank and the desiccant chamber). I would not regenerate oil vapor soaked desiccant in a 'home/kitchen' oven.

Make it easier on yourself.
Condensation in a tank is only a symptom that the oil is ALREADY totally saturated with water. The principal reason that oil becomes saturated with water is 'chemical equilibrium' through the vent that is in contact with the ambient wet atmosphere, not 'condensing water on the tank walls'.
If you want 'dry' fuel, only buy 'fresh' fuel - from a high turnover 'truck stop', avoid marinas where the fuel is 'old' and possibly water saturated. If you 'must' buy from a marina, seek out those that cater to 'watermen' and commercial folk' as a high turnover marine source is vastly 'drier' than a 'marina'.
Dont top off your tank, keep the MINIMUM of fuel onboard plus some reserve. The less amount of fuel in the tank, the less water 'uptake'.
If 'condensation' was a valid argument, we wouldnt need to drill water wells as all we'd need to do is put empty vented tanks out and they would fill automatically with water ... and we know that isnt true. If you keep the minimum amount of oil in the tank, remove the oil for when long-term non-use, put in only 'fresh/dry' oil ..... you most probably wont need a desiccant trap.

:-)

[trlrtrsh]

RichH, Thanks for the speedy reply. You keep mentioning "oil" and I was referring just to the deisel fuel. The information you have supplied is basically what I'm looking for. So far I have not ventured too far from my home Marina, but have plans to do some extended cruizing. Like I said in an earlier post, I currently have no problems with my fuel. I live in Central Calif on the Delta, but I plan to go North to Washington State Puget Sound, and when it gets cold head South for warmth. My concerns are the change of climates does it deserve the attention of preventative action, or just keep a eye on the water trap in the supply line. The information you gave me gives me some ideas on questions too ask prior to and/or if I decide to invest in them. (Right now it's looking doubtfull that I will). Again, thanks for your input, it is spot on what I was looking for.

[RichH]

Diesel is essentially #2 oil ... the same as #2 oil burned in home heaters.

If you are traveling, you will be consuming and adding 'new' oil.
The 'water' problem usually occurs when the oil (diesel) is 'sitting around' for a long time and in direct contact with the atmosphere.

Fresh fuel is essentially dehydrated by the high temps of the refining process .... let it in contact with moist air and the moisture 'equilibrates' into the fuel. Simple as that.

[pdqaltair]

Second everything Rich said. I too have used these on chemical tanks but I question the need for diesel.

Please post a link.

[Minnewaska]

No first hand experience with the desiccant filter described, but I would want a Racor fuel/water separator in either case. The desiccant could fail and I still want separation. As described, if you take good measures, the Racor is probably fully sufficient.

Whether or not you have sufficient water in the fuel to create combustion or oxidation problems, you may have enough to encourage bacterial growth. Simply adding a biocide at each fill up is the best solution. About $10 worth can last for years.