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Old 24-03-2013, 11:13   #46
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Re: The inside of a fuel tank

drawing from the very bottom of the tank to suck up small amounts of contaminant is actually a great idea for a tank that is new or clean to begin with, and we actually build home heating furnace tanks with a slope and bottom outlet for that very reason. Don't reinstall the pickup tube on an old dirty tank though, or a badly plugged pickup tube will likely result.
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Old 24-03-2013, 11:41   #47
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Re: The inside of a fuel tank

thanks jedi....my education continues.
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Old 24-03-2013, 11:43   #48
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Re: The inside of a fuel tank

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Originally Posted by delmarrey View Post
Every spring with this device I drain my tanks into another and back again. If there is anything in there this gets it out.

.
I don't understand how your contraption works. I don't see any filters. Could you elaborate a bit on the procedure?
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Old 24-03-2013, 14:11   #49
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Re: The inside of a fuel tank

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Originally Posted by minaret View Post
So glad my tanks have built in sumps with bottom drains. All I have to do is open a valve to drain any water or sludge out of the tank, and if there is water in the tank instead of covering the whole bottom of the tank it is concentrated in just the sump.
That's a good set-up. Mine, (5 x 70gal) are purpose built custom 3/16 SS welded to fit the shape of the hull. That places a low sump a bit below the fuel port. There are also 12" x 18" inspection ports on top. Sucking stuff from the bottom corner pretty well removes any water.

We found 1 to 4 inches of water in the various tanks. The main day tank feeding the engine had the most with a 4" layer of what looked like rotted garden slugs. After emptying, I sprayed gallons of Orange Hand cleaner with a pump sprayer and let it set for a few days. Then I used a pressure washer to blow the crud loose.

BTW, our marina, old time diesel service place swears one of the biggest contributors to water in the tanks is poor sealing deck ports. They keep a pile of new O-Rings on hand and replace the cracked ones for free.

I replaced also all of the 1" rusty steel fuel pipes and 1984 valves. The tank ports are all BSP and the new valves are NPT so I had to make the new SS pipe nipples to fit by length at each tank and with alternate threads on each end. It was nice to have the machine shop & power threader outside my office door.
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Old 24-03-2013, 14:28   #50
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Re: The inside of a fuel tank

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Originally Posted by s/v Jedi View Post
I agree that polishing is the key. I am still burning 5 year old diesel from Colombia which isn't very clean, without any issue. I polish now and then (using a bottom connection in the sump but you can add a suction pipe all the way into the sump from the top of the tank too if you want to adhere to code) at 10 microns and my primary filters can be 2 microns without ever plugging up. I also use Startron enzyme treatment every 6 months plus when I get new fuel.

The diagram I posted before contains a full polishing system; I used the Nordhavn system as the base for it. For sailboats with Racor 500 class filters, the Walbro 6802 I used is a match with the filter and performs fine; but it has been replaced with an even better pump. Maximum pressure from the pumps should be at or below 7 psi. This is of importance for both the filters and the high pressure pump on the engine in case of the bleed/boost pump.
Sounds right. I polish at 30 microns, transfer to the day tank at 10 microns and have 2 micron filters on the engine and genset.

Like everything boating, there seems to be little agreement on the desirability of polishing one's fuel, even though everyone who does it reports its advantages. Like bypass filtration on the engine oil, I've yet to hear the really convincing argument why clean diesel or oil isn't better than less clean diesel or oil.
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Old 25-03-2013, 08:28   #51
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Re: The inside of a fuel tank

Jedi,

What is the boost pump that replaced the Walbro 6802 in your system? How is the replacement better?

Roger
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Old 25-03-2013, 10:18   #52
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Re: The inside of a fuel tank

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Jedi,

What is the boost pump that replaced the Walbro 6802 in your system? How is the replacement better?

Roger
No, Walbro replaced it with a newer model since I bought mine. They stated the new model was improved and some other owners I know had a problem with a spring in the 6802... which was easily solved with another spring but I guess that is the improvement Walbro has a table on-line that lists the matrix with replacement model numbers for the discontinued pumps. Keep an eye on that 7psi max output pressure, although most engines and filters are rated for 14-15psi so there is some room.

Please also note that there are two pumps in my system. The transfer/polish pump has an old-fashioned mechanical time-switch so that you can set and walk away. This works well for both polish and transfer of fuel. Transfer is just polish with return to the other tank.

If you have one tank you can also polish; rule of thumb is to filter 5 times the volume of the contents. So you have to run it 5 times as long as when you can transfer the filtered fuel to another tank.

I recommend a vacuum gauge or sensor on the filter that feeds the pumps. This will be the filter that needs replacing most often.


Edit: do not use teflon tape for assembling the manifolds! I used Permatex high temperature thread sealant for hydraulics. You need high grade or it will leak or worse, introduce small particles into the fuel feed!
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Old 25-03-2013, 10:32   #53
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Re: The inside of a fuel tank

And this is the tool for the clamps; it's awesome but you need a little room to access the clamp with the tool, so there will always be some that you need the big ugly skin-cutting clamps for. This tool sounds expensive but just count how much good quality hose clamps cost vs a piece of wire! It'll be cheaper to have the tool. With effort you can still find Monel wire which works much nicer than stainless steel although they now claim to have Monel-like steel wire.

You'll never cut yourself on these clamps unlike the regular ones.

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Old 25-03-2013, 12:02   #54
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Re: The inside of a fuel tank

The range of pumps is rather wide - FRA, FRC, FRB, FRD - with additional divisions within each range ... so I was curious which particular pump(s) you selected. The FRC & FRB pumps are "on-demand" pumps, for example, and the FRA & FRD pumps are activated by "power on/off." A select few are suggested for continuous operation. Just hoping to take advantage of your experience.

Roger
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Old 25-03-2013, 12:13   #55
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Re: The inside of a fuel tank

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Originally Posted by svtrio View Post
The range of pumps is rather wide - FRA, FRC, FRB, FRD - with additional divisions within each range ... so I was curious which particular pump(s) you selected. The FRC & FRB pumps are "on-demand" pumps, for example, and the FRA & FRD pumps are activated by "power on/off." A select few are suggested for continuous operation. Just hoping to take advantage of your experience.

Roger
I think they just went bankrupt:

Quote:
Special Notice!

We are currently not accepting any orders until further notice. All Orders will be REFUNDED
Walbro Fuel Pumps

Also, see this link: Walbro - Walbro Marine Electric Fuel Pumps, 7 PSI, 12v & 24v, Disconti

Quote:
6802 (was 6092) = FRB-13-2 (12v)
This is the 2nd link when you Google for "walbro 6802 pump replacement"

ciao!
Nick.
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Old 25-03-2013, 12:33   #56
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Re: The inside of a fuel tank

great thread +1
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Old 30-03-2013, 00:16   #57
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Re: The inside of a fuel tank

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I don't understand how your contraption works. I don't see any filters. Could you elaborate a bit on the procedure?
Sorry for the late reply, just got back from the Philippines.

Basically, it's a raw water pump w/a nitrile impeller attached to a washing machine motor. With a diesel truck filter all mounted to a deck board. I mounted the filter up steam of the pump since my tanks are fairly new/clean.

If I were to pump sludge from a tank then a strainer, then a filter would be before the pump, so not to cause any damage to the pump. But if it were really that bad I'd go with a diaphragm pump.

In the picture a 1/2" copper pick-up tube is attached to a clear hose going to the suction side of the pump. The discharge side of the pump goes to the filter and then onto the fuel jug. The filter is also a water strainer with a drain valve at its base.

When returning the fuel to the tanks I just put the pick-up tube in the jug and outlet into the tank, for a double scrubing.

On my tanks there are two 1" pipe fitting holes at both ends and I can see in the tanks by pulling the gauge sender unites. If I see anything in the tank I can direct the tube towards it to pick it up.

Obviously, the second tank in the pictures is not mounted yet. It's custom made to fit between the solon settee back and hull stringers.

If the boat were big enough I'd install a full time system similar to Jedi's.
.
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Old 30-03-2013, 01:22   #58
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Re: The inside of a fuel tank

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Two-fold: bleeding the filters and line, pump, injectors is one and boosting fuel delivery through dirty filters is two. The latter one is in case you need the engine urgently even though a filter is plugged up. I also use it to run the last bit of fuel out of my tank, as it draws from the very sump.

I am always amazed that people like to draw fuel somewhere up from the bottom of their tanks. This allows crud and water to accumulate in the bottom. It is much better to always draw from the bottom so that any dirt and water accumulates in the filter instead. In my view of-course, but it is the view based on logic
Sometimes logic can be failed for any number of reasons.

At best you can call you system design an axillary filter system.

1. A true polishing system takes fuel from the bottom of the tank and returns it to the bottom of the tank(s).

2. If you let diesel aerate then you are fouling the fuel.

3. A real fuel polishing system is wholly separate of the delivery system, with it's own autonomous filters.

4. Fuel pick up from a 5-15%(depending on shape) margin from the bottom of the tanks for the delivery side will not ingest water and contaminants into the run(primary) side of the fuel system, unless you fail to polish the tanks.

Fine you can filter a fuel transfer to what ever you like to imagine, but it is not doing a thing for the donor ship.

Now lets say we have a 6-71 gimmy it runs somewhere about 60 to 70 gallons per hr, but it only burns 12 gal. per hr, what we have under your scenario is a fuel polishing system, but it's not. It's an auxiliary filter system.

Remember a real fuel polishing system takes the fuel from the bottom of the tank(aka a water trap) and returns it below the fuel level.

Now in modern day when we design a real on-board fuel polishing system we take fuel from the top by way of a dip tube, that reaches to the bottom, with intakes perforated into each baffled area, then re-turn it to the same area perforated in each baffle.

What this does is turn all of the sediment into floating/distributed debris, which is quickly sucked up by the vacuum of the re-circ pump/filter/water trap.

This is completely independent of the primary fuel system, and we always run independently, prior to running the primary fuel system.

Lloyd
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Old 30-03-2013, 02:04   #59
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Loyd you should learn to read. Until then, you will write posts like these that are wrong. Study my system before commenting on it. Realize that this is the Nordhavn system.
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Old 30-03-2013, 11:49   #60
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Re: The inside of a fuel tank

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Originally Posted by s/v Jedi View Post
Loyd you should learn to read. Until then, you will write posts like these that are wrong. Study my system before commenting on it. Realize that this is the Nordhavn system.
Nick,

7 lb psi is not going to provide much in the way of scouring the tank bottom. Especially if its just dumping in one place. Now if you want to open the tanks and use the 7lb psi and a wand, maybe.

I think your quote says it all
Quote:
I am always amazed that people like to draw fuel somewhere up from the bottom of their tanks. This allows crud and water to accumulate in the bottom. It is much better to always draw from the bottom so that any dirt and water accumulates in the filter instead. In my view of-course, but it is the view based on logic
A properly polished system won't have accumulated crude and water. And designing a system to purposely ingest the crude and water, is a poor choice. It Might be fine for a boat running a big jimmy, set up with big filters.

The newer diesel engine that doesn't use fuel flow for cooling just will not move enough fuel to accomplish anything, except cause filter changes more often on the primary fuel system.

Lloyd
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