Fuel breather vent desiccant moisture separator

[Joeparker]

With ethanol fuel, I’m having a lot of moisture coming through my vent and absorb into the fuel. Has anyone thought of ever putting a desiccant moisture absorbent filter on the vent line similar to an air compressor? This way the air going in and out of the tank would be absorbed into the desiccant filter. Would there be a problem with the system?

 

[ShadBurke]

Are you sure moisture is coming in thru the vent line? Is the vent line "looped" on the inside of the vent screen?

What year is the vessel? What year is the fuel tank? What year are the hoses to/from the fuel tank (Fill, vent, pick-up)?

 

[bman440440]

With ethanol in todays fuels it pulls moisture out of the air so yes technically the moisture is coming in threw the vent line... as the fuel is being consumed the vent lets air into the tank and along with that air is moisture so in theory that filter should work... as long as it does not restrict air flow I would think it will work.

 

[sickcat]

I like the idea - never tried it. I still consider putting shut offs on the vent to close when the boat is sitting. Never had any water issues so that project keeps sliding down the to do list. My boat lives in the water so the fuel tank temps stay very consistent as with no venting over pressurization with temp swings is a concern.

The setups shown look like they come from diesel shops - are they rated for gasoline? Diesel and gasoline vapors are 2 very different things. Other concerns I see is mounting it so it doesn't get saturated when the tank is full and the vent burbs fuel. and is if the unit is serviceable and what will access be like to do that.

 

[Joeparker]

Are you sure moisture is coming in thru the vent line? Is the vent line "looped" on the inside of the vent screen?

What year is the vessel? What year is the fuel tank? What year are the hoses to/from the fuel tank (Fill, vent, pick-up)?

Boat is a 2000 2520 Parker fuel tanks replaced in 2019 along with all fuel hoses. Tank holds pressure when all outlets are capped. Boat is stored in a place where there is large temperature swings inland, San Diego county. I thought the vent going to the outside of the hull of the boat may have been an issue placed a clam shell over it moisture is only a problem when storing for 2+ months. I have two 10 µm filters that seem to be catching the water before it reaches the engine just can’t stand seeing water in my filters. I also use marine stabilizer in my fuel. I do not have a loop in my vent line.

 

[Joeparker]

I like the idea - never tried it. I still consider putting shut offs on the vent to close when the boat is sitting. Never had any water issues so that project keeps sliding down the to do list. My boat lives in the water so the fuel tank temps stay very consistent as with no venting over pressurization with temp swings is a concern.

The setups shown look like they come from diesel shops - are they rated for gasoline? Diesel and gasoline vapors are 2 very different things. Other concerns I see is mounting it so it doesn't get saturated when the tank is full and the vent burbs fuel. and is if the unit is serviceable and what will access be like to do that.

Talk to the company they said it would work for gasoline with ethanol. I also thought about the burping issue was thinking of putting a catch container between the filter and the tank with a drain valve on the bottom.

 

[jigstrike]

Always store the boat with a full tank of fuel. That limits the surface area exposed to air and thus limits the ability to pull moisture

 

[aguachico]

Dealing with fuel contamination

How does salt water get pass 3 filters? ethanol?

crazy shit

 

[Joeparker]

Always store the boat with a full tank of fuel. That limits the surface area exposed to air and thus limits the ability to pull moisture

I try to do that as much as possible

 

[dwaynesda]

I have thought about this problem for a long time. When the boat is just sitting in the driveway or slip, the tank breaths in and out. When the sun is up, everything is expanding in the fuel tank (air and fuel). When the sun goes down, everything in the fuel tank is contracting, and the tank breathes in a "fresh" batch of air with new moisture in it. This new moisture is what reacts with the alcohol in the fuel tank. Everyday a little bit of moisture will settle in the tank when the tank "breathes".

I have always wondered if you just put a heavy balloon over the vent line fitting what would happen. The balloon would probably expand during the day, but........................... it would not be bringing in a new batch of air with new moisture at night. It would just be rebreathing the same air over and over again, minus the moisture.

I was thinking that might be an easy solution to keep the "new" moisture from entering the tank every night when the air contracts.

I have never done it but have always wondered about it.