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Old 04-03-2019, 02:01 PM   #121
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Originally Posted by sunchaser View Post
The safe assumption is , there will be free water in any large fuel tank that spends most of it's life sitting. That is why Steve D designs fuel tanks with sumps. And FF preaching same forever. As has been done for over a century.

Debating the degree of condensation has in fact been done, by fuel suppliers that have a spec to meet. Thus busting their tails to design and operate pretty neat water catching systems prior to that fuel being delivered to the customer.

The amount of condensation related water in fuel farms is surprising and constantly measured by both water collected and analysis on both ends of the fuel farm. But, does it matter for us small use boaters? Probably not if you don't let water get into your tanks to begin with.

The three primary sources of water as mentioned on TF are deck fills, vents and fuel coolers. A fourth, rusty worn out tank tops on a neglected vessel with leaky teak decks. Another, the onshore storage tanks!

www.hpcdfuel.com/pdf/DOWfuel_training.pdf
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Old 04-03-2019, 02:23 PM   #122
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Very large fuel tank storage facilities?

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Originally Posted by smitty477 View Post
...this is also what I have seen in very large fuel tank storage facilities.
Very large fuel tank storage facilities like these? Where a floating roof is used to prevent wet air from ever touching the fuel? Or from ever touching the metal sides of the inside of the tank?

Note that the 'floating roof' design (also called a 'variable volume' tank) is functionally equivalent to keeping the tank completely full at all times...

I'm sure there's no real engineering here. All just quackery. Big companies who hire real engineers to figure out these things just like to waste money on useless 'theoretical' problems.
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Old 04-03-2019, 02:53 PM   #123
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Originally Posted by Riverguy

It can't have come in to the tanks, because he's been filtering every fuel fill before it came into the boat...


[QUOTE=Delfin;753991]That isn't what he said.

Yes, I think it is what he said...

"FYI, I always polish new fuel through a 2 micron Racor 1000 into my "day tank", and the 10 micron filter I just changed pulls from the day tank and provides fuel to the on-engine filter."

The "day tank" and "storage tank" are normally kept separate. I've heard transatlantic sailors use this lingo. Brian can speak for himself but I'm pretty sure this is what he means. When filling up in port, one fills the storage tank. Then the smaller "day tank" (named so because it is supposed to hold a 'days worth' of fuel) is then filled from the larger storage tank. This is for safety and redundancy -- a bad load of fuel in your storage tank won't necessarily cripple you at sea, because your "day tank" stays clean. Because the "day tank" is smaller, it doesn't have to hold fuel for a long time.

https://www.morganscloud.com/2009/12...fuel-day-tank/

Another reason for having a 'day tank' is to eliminate the need for a lift pump.

Anyway....somehow, Brian got a nasty microbial infestation in his 'day tank'. That's why his filter media was covered with black slime.

Microbes cannot grow in diesel unless significant liquid water is present.

How did the water get in there to feed the microbial infestation? This is an interesting question because the "day tank" normally would not have a deck fill...
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Old 04-03-2019, 02:54 PM   #124
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Old 04-03-2019, 03:05 PM   #125
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Greetings,
Mr. fb. Indeed, you provided belt sander AND assistance-thank you BUT that was for the dirt place. I'm pretty sure we're talking marine here.
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Old 04-03-2019, 04:23 PM   #126
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Originally Posted by Riverguy View Post
Very large fuel tank storage facilities like these? Where a floating roof is used to prevent wet air from ever touching the fuel? Or from ever touching the metal sides of the inside of the tank?

Note that the 'floating roof' design (also called a 'variable volume' tank) is functionally equivalent to keeping the tank completely full at all times...

I'm sure there's no real engineering here. All just quackery. Big companies who hire real engineers to figure out these things just like to waste money on useless 'theoretical' problems.
"Very large fuel tank storage facilities like these? Where a floating roof is used to prevent wet air from ever touching the fuel?"
No - the tank farms we worked in were fixed roof tanks with large open areas during low tank levels, in NJ, NY and Penn.
When you are actually inside them you know how large of an open surface area is exposed. We did hot and cold butterworthing on larger tanks as well as leak work and formal inspections.
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Old 04-03-2019, 05:30 PM   #127
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I'm starting to see the benefits of the Ignore button.
Dammit, Delfin, that was going to be my reply!
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Old 04-03-2019, 08:40 PM   #128
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Dear Mr. Riverguy

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Originally Posted by Riverguy View Post
Re: "I have always thought this was bs. Why doesn't it happen on cars? My boat goes through several seasons to include the Bahamas in winter and I have never seen a drop of water in three system."

It does happen in cars. It doesn't happen AS MUCH in cars because the fuel tank is not sitting in a water-cooled bilge that will typically be much cooler than the ambient air outside...you'll read about this in the link below.

re: "I have never seen a drop of water in three system."

How would ever you see it? Since the water is almost certailny never going to make up the pick-up pipes and into your fuel bowl, how would you know? Do you have transparent tanks? I for one can't see through the aluminum my tanks are made of.

Don't you think it odd that Practical Sailor would devote so much effort and testing to a problem that doesn't exist? Here are 25 hits on articles they've written on this "bs" including several tests of various biocides.


https://www.google.com/search?q=%22b...cal-sailor.com



This one in particular...


https://www.practical-sailor.com/iss...es_5800-1.html

While you're at it, what's your take on the photos that kick off this thread? what is that black slime on OP's filter? It can't have come in to the tanks, because he's been filtering every fuel fill before it came into the boat...
I dont have to know what the stuff is. I know it is not water. I have never, in hundreds of thousands of miles driven, had water in my fuel. I dont haveto have clear fuel tanks, only clear Racors to see water. After years of boating, in all seasons, i would ecpect to see water accumulation if it was coming from condensation. So far, none seen. I think SteveD is on the right track with his investigations. As far ad practic as l sailor is concerned, i will read your links when i get a chance.
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Old 04-03-2019, 08:46 PM   #129
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Dear Mr. Riverguy

Quote:
Originally Posted by Riverguy View Post
Re: "I have always thought this was bs. Why doesn't it happen on cars? My boat goes through several seasons to include the Bahamas in winter and I have never seen a drop of water in three system."

It does happen in cars. It doesn't happen AS MUCH in cars because the fuel tank is not sitting in a water-cooled bilge that will typically be much cooler than the ambient air outside...you'll read about this in the link below.

re: "I have never seen a drop of water in three system."

How would ever you see it? Since the water is almost certailny never going to make up the pick-up pipes and into your fuel bowl, how would you know? Do you have transparent tanks? I for one can't see through the aluminum my tanks are made of.

Don't you think it odd that Practical Sailor would devote so much effort and testing to a problem that doesn't exist? Here are 25 hits on articles they've written on this "bs" including several tests of various biocides.


https://www.google.com/search?q=%22b...cal-sailor.com



This one in particular...


https://www.practical-sailor.com/iss...es_5800-1.html

While you're at it, what's your take on the photos that kick off this thread? what is that black slime on OP's filter? It can't have come in to the tanks, because he's been filtering every fuel fill before it came into the boat...
I dont have to know what the stuff is. I know it is not water. I have never, in hundreds of thousands of miles driven, had water in my fuel. I dont haveto have clear fuel tanks, only clear Racors to see water. After years of boating, in all seasons, i would ecpect to see water accumulation if it was coming from condensation. So far, none seen. I think SteveD is on the right track with his investigations. As far ad practic as l sailor is concerned, i will read your links when i get a chance.
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Old 04-03-2019, 08:55 PM   #130
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Faulty science, faulty math and no documented experience.
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Old 04-03-2019, 11:18 PM   #131
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Quote:
Originally Posted by Riverguy View Post

Don't you think it odd that Practical Sailor would devote so much effort and testing to a problem that doesn't exist? Here are 25 hits on articles they've written on this "bs" including several tests of various biocides.
]
..
Paid infomercials
Where do you think they make their money from?
Quote:
While you're at it, what's your take on the photos that kick off this thread? what is that black slime on OP's filter? It can't have come in to the tanks, because he's been filtering every fuel fill before it came into the boat.
Leaking deck filler.
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Old 04-04-2019, 08:03 AM   #132
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Originally Posted by Ski in NC View Post
Riverguy- I generally agree with what you posted, but there is one important detail that you left out: Air exchange through the vent system.

True that thermal inertia (ballast in your terms) of a half load of fuel will cause fuel to often be below the dewpoint of the outside air, depending on what the cold/warm fronts are doing. Those fronts can have quite wide swings of temp and humidity here in the southeast.

But there is not any significant flow of air in and out of the vent. Usually several feet of 5/8" ID hose. Yep due to thermal changes and barometric changes there will be some flow in and out of the vent. But do the math and the volume through those mechanisms is very small as a percentage of trapped air volume above the fuel level.

If there is not significant air flow through the tank from the outside air, the moisture content of the air above fuel simply will not change much.
Ski, you beat me to it, in order to generate significant condensation the movement of water-laden air into the tank has to occur.

To clarify, my test was done on vessels that were hauled out, tanks were partially full, so a generous air space, access ports were only removed for the inspection and then replaced.

One possible reason PS has written so much about this...because the myth is so pervasive.

Having said all that, regardless of the source of the water, it may not matter, what's important is it does occur to greater or lesser degrees from vessel to vessel, and therefore there should be a means of removing it. Ideally it's a sump and drain, or stripper tube. In other cases it's the primary fuel filter, however, in that case some water will remain as the fuel pick up is not close enough to the bottom of the tank to remove it all.

Water left in metallic tanks will cause corrosion, and water will support biological life in any tank (a byproduct of bacteria colonies in tanks is hydrogen sulfide, which is corrosive, as well as the skeletons of the single cell organisms when they die). Biocides address one of these issues, but not the other and I believe they provide a false sense of security.

I've replaced aluminum tanks that were just a few years old as a result of water entry, bio-fouling and corrosion, the tank bottoms looked like the proverbial Swiss cheese. See page 6 in this article https://stevedmarineconsulting.com/w...imer115_04.pdf for details on contamination. Attached are a photos of the insides of a bio-fouled tank and the bottom of the tank whose bottom corroded as a result of water entry/contamination.

This article shows the inside of some contaminated tanks and filters https://stevedmarineconsulting.com/c...-diesel-tanks/

In the case of the young tanks that were replaced, the water source turned out to be a hull mounted tank vent that intersected with the vessel's bow wave at just the planing transition speed, every time it passed through that transition, a slug of water would be pushed uphill and into the tank.
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Old 04-04-2019, 08:53 AM   #133
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Yep, water gets in tanks and causes all sorts of grief. Vents and deck fills primary culprits. But not likely condensation as discussed.

On my personal boat I had the tanks made before I realized I wanted sumps. Too late. So put the main engine pickups right against the bottom so if any water gets in there, it will not accumulate. My engine is the stripper tube!! So far, so good.

The vent line it goes through a PVC catch tank in ER so if any water gets drawn in, it will drop out in the catch tank. Drain cock checked every now and then, never seen any water so all good.
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Old 04-04-2019, 09:44 AM   #134
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Originally Posted by sunchaser View Post
A few questions and comments:

How many gallons of fuel have you burned through that filter?
How old is the fuel in the boat's tanks?
Where did you fuel up the last few times?
What micron rating?

Looks like the filter is doing what it is supposed to. I've seen a lot worse after about 1/2 your hours.
We burn a little less than 7 gallons / hour, but of course, a lot more than that goes thru the filter every hour.

The fuel has been refreshed regularly over the 13 months since I changed the filter (422 hours x 7 gph is almost 3,000 gallons, and we hold only 1,000). But at the time the filter was changed, we hadn't put much fuel through the system in the previous year, so some of that filter's life was filtering some not-so-fresh fuel.

We've bought fuel in Nassau, Providenciales, and Salinas (PR) during that time. Since all fuel goes through the 2 micron filter before it goes into our "day tank", and that filter has never gotten really cruddy, I feel like we've never gotten any bad / dirty fuel.

As noted in the OP, the filter in the pic is 10 micron, and everything goes through 2 micron on its way into our day tank.
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Old 04-04-2019, 09:48 AM   #135
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Condensation is a non issue with the size tanks and vents used on dude boats. As others have pointed out, if you have enough water in your tanks that it collects in puddles, that water is entering through fills or defective vents. That is why no one without these defects ever report on any water issues in their fuel.

Some tanks have shapes or locations that make including sumps pretty difficult. My wing tanks are about 18 feet long; the bilge tank is under the engine. All have external taps for drains, but my defense against moisture of to polish a tank when it is almost empty while in a seaway and use an emulsifying additive. Never seen any water on inspection, and I doubt I ever will.
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Old 04-04-2019, 09:57 AM   #136
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We burn a little less than 7 gallons / hour, but of course, a lot more than that goes thru the filter every hour.

The fuel has been refreshed regularly over the 13 months since I changed the filter (422 hours x 7 gph is almost 3,000 gallons, and we hold only 1,000). But at the time the filter was changed, we hadn't put much fuel through the system in the previous year, so some of that filter's life was filtering some not-so-fresh fuel.

We've bought fuel in Nassau, Providenciales, and Salinas (PR) during that time. Since all fuel goes through the 2 micron filter before it goes into our "day tank", and that filter has never gotten really cruddy, I feel like we've never gotten any bad / dirty fuel.

As noted in the OP, the filter in the pic is 10 micron, and everything goes through 2 micron on its way into our day tank.
Thanks for the reply Brian. My guess, the fuel you've picked up may be suspicious or the shore based tanks somewhat fouled. PR has had some pretty rough times of late.
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Old 04-04-2019, 10:14 AM   #137
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Did the OP ever come back and state the micron size of the pictured Racors?
The micron size of the filter (10) was stated in my original post. Maybe not as clearly as it could have been stated, but it's there:

Quote:
Originally Posted by BrianSmith
FYI, I always polish new fuel through a 2 micron Racor 1000 into my "day tank", and the 10 micron filter I just changed pulls from the day tank and provides fuel to the on-engine filter.
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Old 04-04-2019, 10:31 AM   #138
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Well, wasn't THAT fun? I had no idea such a simple question could start such an... ahem... interesting conversation! (We've been circumnavigating St. John, USVI since my post with pretty poor cell service, so I'm just now reading all the replies.)

To address several comments and questions:

1. I polish all fuel from my two 400 gallon bulk tanks into my two 100 gallon "run tanks" (aka day tanks) through a Racor 1000 with a 2 micron filter. I have never seen more than 9 inches of vaccuum on its gauge, and normally it's 5 - 7. AFAIK, I've never gotten any dirty fuel, because I've never seen this filter become clogged. I change it when the vaccuum is consistently above 7". To whoever said this was a waste of time I say "codswallop!" - just because it's never trapped a lot of crud from a load of bad fuel before doesn't mean that it won't do that in the future, if I ever do get a load of bad fuel.

2. I've never seen a drop of water in the Racor bowl of any of my filters (the genny has its own Racor 500), but I realize that doesn't mean there's not some water in the fuel - maybe enough to support bacterial growth. I've never used a biocide, but I might consider it and see if my filters start to look better after a year.

3. Aside from a little crud in the bottom of the Racor 1000 bowl that showed up there right after I rebuilt the filter over a year ago, I've not seen any crud in the bowls of any of the three Racors.

4. I run the engine at 1400 - 1500 99.99% of the time when cruising, which isn't creating much of a draw on the fuel system, I'm sure. But then again, since that's what I always run at, I don't really care what the vaccuum gauge might show at 2,000 RPM, do I?

5. I do, in fact, have a "drag needle" (aka "telltale") on the gauge, so I'm seeing its maximum reading every time I look at it.

I guess I'll have a look at the filter in a few months, and see if the black stuff is continuing to build up, or if it might have come from old fuel that might have been there prior to my previous filter change. And I'll keep watching the vaccuum gauge, and looking at the bowl, and see if I ever know more about my fuel system than I know right now.
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Old 04-04-2019, 01:48 PM   #139
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i would, and i do, change that kind of fuel filters yearly! also with the glass racor filters, make sure the vacume gauge is working properly! i had to empty out some fluid/glycerin, to get a good air bubble in the unit...clyde
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Old 04-04-2019, 02:02 PM   #140
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Doing the math...(ullage)

Quote:
Originally Posted by Ski in NC View Post
Riverguy- I generally agree with what you posted, but there is one important detail that you left out: Air exchange through the vent system...Usually several feet of 5/8" ID hose. Yep due to thermal changes and barometric changes there will be some flow in and out of the vent. But do the math and the volume through those mechanisms is very small as a percentage of trapped air volume above the fuel level.

If there is not significant air flow through the tank from the outside air, the moisture content of the air above fuel simply will not change much.
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Ski, you beat me to it, in order to generate significant condensation the movement of water-laden air into the tank has to occur.
Re: "But do the math and the volume through those mechanisms is very small as a percentage of trapped air volume above the fuel level.

Nope, and I did do the math. During a single 24 hour cycle, it's between 5-16%, depending on temperature. That's actually very large. Over the course of a week or so, it's more than large enough to maintain the inside of the tank at the same RH as the outside air.

Let's walk through the math...

A 300 gallon tank that's 10% full will inhale and exhale a total of 3,050 cubic inches of air in a single 24 hour cycle where the temperature swing is a mere 13 degrees F. You're both capable of doing this math (remember to convert to Kelvin) but if you want to avoid the effort, send me a private message with an e-mail address and I will send you the spreadsheet. It's pretty simple.

Don't think of the vent hose as any kind of 'buffer'. 3,050 cubic inches is many hundreds of times the volume of air in a typical vent hose.

Remember, this happens every day, so multiply by 365 and you'll know how much water laden air you are ingesting over time. Remember, this is on a mere 72-85 degree swing.

What if we use SteveD's test conditions where he experiences...

"...temperature swings of 40F are not uncommon in 24 hrs as warm fronts move through..."

PV = nRT gives us 9,900 cubic inches in 24 hours. That's about 16% of the tank's ullage...in one day. That's six cubic feet per day and 175 cubic feet per month.

Re: "in order to generate significant condensation the movement of water-laden air into the tank has to occur".

Right...and it does. 10% per day (on average) is more than enough.

And if it weren't...there are several other factors that folks also neglect to consider. I'd be happy to explain these also, but I think PV = nRT is giving us plenty.
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