My take on DIY fuel polishing system (15 Gal per min)

[Waterant]

Hey guys,

I want to share my DIY fuel polishing system because everything I found on youtube, and forums and being sold out there is way too slow for 400-gallon tanks and would take hours to do one fuel rotation.

My system does 15 Gal per min (measured with a 15 Gal bucket).
so each 200G tank takes only 14 minutes to rotate once (with clean filters).

Two filters. For the first rotation, I used 80 Micron mesh in the first filter and 17-micron water-absorbing fuel filter element for the second filter just to filter out the bigger crap from the tanks on the first run.
A permanent setup will be 17-micron water separator first and 10 micron filter second.

One 3/4" ID hose comes from the bottom of the port tank, and another is from the bottom of the starboard tank.

One 3/8" ID hose is going to the opposite side of the port tank return line
another 3/8" ID hose is going to the opposite side of the starboard tank return line - this helps to steer up the fuel in the tank
The third 3/8" hose is going to the diesel heater day tank.

This system can polish the fuel and transfer it from one tank to another to balance them and put the filtered fuel into the day tank of the heater.

I did not invent it - a similar setup is used on the farms to pump fuel from the big tanks into the farm equipment.

It's compact and super fast. The only problem is because of the metal impeller in the pump, it is very noisy. The good news, it takes minutes to rotate a tank once so you do not have to hear it for long.

Components:

1x Self-priming Oil Transfer Pump with metal impeller (110V AC, 15GPM)

1x Goldenrod Fuel Filter Assembly with 10 Micron Fuel Filter (17 micron, 25 GPM max flow rate)

1x Goldenrod Fuel Filter Assembly with 17 Micron Water-Absorbing Fuel Filter (10-micron, 25 GPM max flow rate)

1x Goldenrod (470-5) Replacement Fuel Filter Element (17-micron)

1x GOLDENROD (496-5) Fuel Tank Filter Replacement Water-Block Element (10-micron)

1x Vacuum / Pressure Gauge -30~60Psi Stainless 1/4" NPT 2.5"

2x 3/4 inch Stainless Mini Ball Valve

3x 3/8 inch Stainless Mini Ball Valve

Gasoila - SS04 Soft-Set Pipe Thread Sealant with PTFE

Backplate and holder blocks are made from starboard or any HDPE plastic 1/2 or 3/4 will work

Steel fittings 1" and 3/4" for hydraulic lines were purchased locally.

The total cost is ~$300

I already ran it for 30 minutes on each tank (both are half full) and did not notice any issues. If you see any problems with it, comments and suggestions are always welcome.

 

[Delta Riverat]

Looks good. Yeah, mine takes hours, just a trickle. But cool for filling up those fuel filters after a change. And they don't get warm from running for hours ether.

Just takes a long time.

 

[O C Diver]

Wonder if some of the noise is from back pressure on the pump. 15 GPM through 3/8" hose is too small, IMO. There's a reason the output fitting on the pump is 3/4" NPT.

Ted

 

[Waterant]

my goal was to avoid that "running for hours" thing. Plus, I do not have any tank inspection hatches to get there with a brush, so I wanted to have a good flow inside the tank to steer things up. And it's not that hard to build: a pump, two filters, and a few fittings - anyone with a pipe wrench can do this.

110V pump was also my preferred choice because it has plenty of power and runs on a standard power cord. Equivalent in 12V would require heavy gauge wires directly from the battery, which would cost more than the whole system. And because I plan to do this once or twice per season or right after a rocky run, I'd be running a generator or connected to the shore power any way to do 30 min of pumping.

 

[O C Diver]

Do yourself a favor. Remove one hose and adapt the fitting to 1/4" NPT. Put a 300 PSI pressure gauge on the fitting. Open that valve plus one to another tank, and then run the pump. If you're getting 15 GPM through 3/8" hose, the pressure has to be very high. What's the pump rated for?

Ted

 

[Waterant]

Wonder if some of the noise is from back pressure on the pump. 15 GPM through 3/8" hose is too small, IMO. There's a reason the output fitting on the pump is 3/4" NPT.

When i got that pump, i ran it for a couple of seconds to make sure it worked, and it was as noisy. maybe because it's made in china or maybe all metal impeller pumps are noisy.

but you are right, 25' of 3/8" hose will probably reduce the flow rate even with increased pressure. my tank fittings for return hoses are 3/8", I do not see any way around that.

the only way i can measure the flow is by how fast the day tank for the heater is being filled. It takes under 11 seconds to fill a 2.6 Gal tank via 3/8" ID hose ~4' long, and this is 15GPM as per pump specs.

 

[Waterant]

Do yourself a favor. Remove one hose and adapt the fitting to 1/4" NPT. Put a 300 PSI pressure gauge on the fitting. Open that valve plus one to another tank, and then run the pump. If you're getting 15 GPM through 3/8" hose, the pressure has to be very high. What's the pump rated for?

thanks, I'll try.
The manufacturer said that pump can produce around 21psi.

but it's a good point, I found some references to the lost flow and pressure when using 3/8 in and 3/8 out with 200' of hose length but nothing about 3/4"-in and 3/8"-out with only 25' hose.

and i get the rated flow with 4' of 3/8" hose into the heater tank where i can measure that flow rate; 25' into the big tank may not be that much different.
but it will be an interesting experiment to measure the pressure at the end.

 

[Delta Riverat]

Gear pumps are loud.

 

[Jeff F]

Out of curiosity, what advantage does flow/pressure bring to onboard filtering?

 

[Irish Rambler]

If your diesel tank is fitted with a drain tap, simply put in a 'T' piece with a lever valve. When the boats been moored for 24 hrs, simply drain off a glass beaker full very slowly and hold it up to the light. You will see any water or sediment, if you have either, attach a piece of clear tube to your 'T' piece and drain very slowly until the diesel runs clear.
Job done.

 

[O C Diver]

Out of curiosity, what advantage does flow/pressure bring to onboard filtering?

My tanks are setup where I take fuel onboard in the port tank and transfer it to the starboard. By doing this, all the fuel that gets moved is 100% polished in one pass. Having a larger faster pump reduces the time.

When polishing a tank where your drawing from one and returning it to the same one, time is also reduced but design is very important. As many of our tanks are long (mine is very roughly 2 × 2 x 10), it's important to draw from one end and return to the other end. Otherwise you essentially keep running the same fuel through polisher. What is important to understand is that it will take many turnovers of the same tank to filter most of the debris out. Essentially, you are mixing the polished fuel with the dirty fuel, lowering the contaminant level of the tank over all.

The more efficient way to polish fuel is to have two half tanks of fuel, where your pumping all the fuel into one tank and then pumping all the fuel to the other. If you have long tanks where the draw and the return are at opposite ends, drawing the tank down to 10 to 20% may generate a significant flow across the bottom with a higher volume pump, which may move loose debis.

Ted

 

[Waterant]

Out of curiosity, what advantage does flow/pressure bring to onboard filtering?

For me, high flow means that one circle will be done quickly (the tank content is filtered once), and higher pressure means the tank's content will be disturbed to lift the crap off the bottom and get it into the intake hose.

With a slow, low-pressure filtration, it feels to me that the good fuel will just slowly move thru the filters while sediment will be sitting at the bottom of the tank undisturbed. With a slow system, it has to run for hours while you are underway, rolling around in some heavy seas, and we usually try to avoid such conditions.

I saw a few videos of fuel-polishing services cleaning the tanks of riverboats in UK, and they use high-flow pumps with small-diameter outflow tubes. The first reason is to fit into the tank's fill hose with the intake tube, and the second is to create enough disturbance in the tank to lift the sediment from the bottom. It takes them 30 minutes or so per tank (I do not know how big those tanks are, but they are probably not very big), and they do the fuel test with a clear jar before and after filtration to show how well it works.

 

[Waterant]

it's important to draw from one end and return to the other end. Otherwise you essentially keep running the same fuel through polisher.

Right. I was lucky enough here to have a 3/4 out at the bottom of one end of each tank and 3/8 intake at the top of the opposite end. One of them is used by the generator return line and I installed a T connection. From what I could find, this will not affect the generator in any way and return line sharing is done by many boat manufacturers. I'll try not to run the polishing and generator simultaneously just in case. which means polishing while on the shore power or via the inverter. Another plus of a fast 110v system is that I do not need to run it for many hours on the inverter.

The more efficient way to polish fuel is to have two half tanks of fuel, where your pumping all the fuel into one tank and then pumping all the fuel to the other.

That's a great suggestion. I'm in this situation now with both tanks half full of questionable fuel inherited from the previous owner. I'll do this "between tanks" transfer the next time.

 

[Waterant]

If your diesel tank is fitted with a drain tap, simply put in a 'T' piece with a lever valve. When the boats been moored for 24 hrs, simply drain off a glass beaker full very slowly and hold it up to the light. You will see any water or sediment, if you have either, attach a piece of clear tube to your 'T' piece and drain very slowly until the diesel runs clear.
Job done.

Where's the fun in that? i need a button or a switch to make things happen.
and you risk having to drain gallons of fuel into a bucket.
plus, there is no way to transfer the fuel between the tanks this way to balance the boat.

When the boats been moored for 24 hrs, simply drain off a glass beaker full very slowly and hold it up to the light.

for me, this defeats the purpose because the sediment will go down to the bottom in those 24 hours and you will not know the true condition of your fuel which will reveal its ugly, dirty face the next time the boat will hit some waves.

 

[Pete Meisinger]

Wow, nice looking system. Not sure many boats would need such a system unless they are in an area with a poor reputation for fuel quality.

Every junction, T, elbow and fitting, even professionally installed could be a source of introducing air into your fuel system unless your filtering system is completely independent of your engine fuel supply.

pete

 

[Waterant]

Wow, nice looking system. Not sure many boats would need such a system unless they are in an area with a poor reputation for fuel quality.

Every junction, T, elbow and fitting, even professionally installed could be a source of introducing air into your fuel system unless your filtering system is completely independent of your engine fuel supply.

Thanks, Pete. My reason for building that system was a lot of fuel of unknown quality and unknown age inherited from the previous owner.

Taking that fuel out and disposing is a very expensive exercise and would not help me in the future, so $300 filtration system seemed like a good option that gives me additional functionality in fuel management for a fraction of the cost of a one-time fuel polishing service or fuel removal.

It is completely independent of the engine fuel supply lines which have their own Racor 900 filters on separate fuel supply and return lines and tank fittings so there are no worries with introducing the air.

 

[KnotYet]

Your combined pressure/vacuum gauge is not optimum for that use. I would
replace it with a full scale vacuum gauge that will have much better resolution.
The combined gauge could then be used after the pump as suggested by OCD.

Very nice installation. I also use hydraulic fittings and hoses for fuel DIY runs.

 

[Waterant]

Your combined pressure/vacuum gauge is not optimum for that use. I would
replace it with a full scale vacuum gauge that will have much better resolution.

Good point. I probably will not disassemble this unit just to replace the gauge but when the Chinese pump will go tits up and I have to replace it, I'll replace to a full scale vacuum gauge at the same time.

 

[Greg S]

If you draw from the same tank that you are putting the polished fuel into it will take you much longer than fourteen minutes to cycle it all, not the fourteen minutes you calculated. Your polished fuel dilutes what’s in the tank and you still have two hundred gallons left to filter.
To understand why I say this, do an experiment for yourself. Fill a glass with a coloured fluid. Cold coffee is a perfect choice. One FILLED glass of coffee, now with a second glass the same size filled with clean water, pour it into the first glass.
Is it clear? Nope. Pour in another. Now a third, a fourth. Should take almost seven glasses of clean, clear water added to the glass of coffee before there is no coffee coloured water there.
Even if it is only six- 6 x 14 = 84 minutes.

Your system looks great and will work well if you give it enough time.

 

[fgarriso]

We have fuel in six tanks all connected to a manifold that allows me to polish, transfer, draw, and return from or to selected tank or tanks.

Have you considered a manifold system to allow you to have additional functionality.

 

[Waterant]

If you draw from the same tank that you are putting the polished fuel into it will take you much longer than fourteen minutes to cycle it all, not the fourteen minutes you calculated.

Yes, I understand the concept of dilution. My "14 minutes" cycle was just to compare with other DIY and commercial systems, which do 20-80GPH vs 15GPM.

To solve the dilution problem, I'll do what was suggested before - take from one tank, polish, and return all fuel to another to make sure I will get most of the fuel via the filters in one pass. My tanks are currently half full and it's a perfect time to do that.

Have you considered a manifold system to allow you to have additional functionality.

In this system, I can take the fuel from any tank and return it to any tank. It's completely separated from the fuel delivery to the engines, and i can not switch from which tank each engine takes and returns the fuel.

At this time, I do not see any need for having this because my tanks are not that large, and I'll be draining and filling them both at the same time. if i get contaminated fuel, it will be in both tanks anyway.

One situation I can imagine is if water gets into one tank, I may want to switch that engine to use the second tank temporarily. but this is what Racors 900 filter is there for and I always have lots of spare filters for a trip.

The issue with such a manifold is introducing many additional points of failure and air intrusion into the engines' fuel delivery systems (as was mentioned in this thread before). I prefer to keep all critical systems as simple as possible.

But with 6 fuel tanks, such a manifold would be a required piece of equipment and a great feature to have.

 

[catalinajack]

Thanks, Pete. My reason for building that system was a lot of fuel of unknown quality and unknown age inherited from the previous owner.



Taking that fuel out and disposing is a very expensive exercise and would not help me in the future, so $300 filtration system seemed like a good option that gives me additional functionality in fuel management for a fraction of the cost of a one-time fuel polishing service or fuel removal.



It is completely independent of the engine fuel supply lines which have their own Racor 900 filters on separate fuel supply and return lines and tank fittings so there are no worries with introducing the air.

Geez, I get your concern about the condition of the fuel in the tank when you got the boat but an expensive, complicated system to address one tank of fuel? A dockside fuel polishing service could have taken care of that. When we got our boat, the two tanks were less than half full. As Ted does, the fuel polisher filtered one tank to another, then back, twice. He used a 2-micron Racor in a clear housing. The result? No water and no crud, zero, none. Eight thousand miles later, I still have never seen crud or water with NO polishing. I attribute this to the fact that fuel is drawn from the very bottom of the tanks, not through a dip tube.

As for those clear filter housings you show in the pictures, they are not ABYC compliant. A heat shield is required. I happen to think that the requirement is ridiculous and totally ineffectual, but it is what it is. Nice setup though.

 

[boatnbump]

It doesn't say anything about what the duty cycle is. I wonder how long that pump will run until it gets hot or burns up. This is the problem I found when trying to replace a pump in a system I had.

 

[Waterant]

Geez, I get your concern about the condition of the fuel in the tank when you got the boat but an expensive, complicated system to address one tank of fuel?

I would not call a contraption with a pump, gauge, and a few fittings "complicated" and at ~$300 it's hardly expensive in the boat terms. I'm pretty sure a single call to a polishing service would cost me more than this in Washington, DC area. Plus, it allows me to move the fuel between the tanks. And it's a fun winter project which can be done away from the boat and installed quickly.

but i do see your point and if such a service is readily available in the area for a couple of hundred $, it may be a good "do and forget" option.

It doesn't say anything about what the duty cycle is. I wonder how long that pump will run until it gets hot or burns up.

it says 30 minutes of continuous run with 30 minutes of rest after. In 30 minutes, it can potentially move 450 Gallons of fuel, so this is long enough for me. They probably have "continues duty" fuel pumps of the same flow rate, but they would cost 10x compared to this pump.

 

[HeadedToTexas]

15 gpm through ⅜ hose would produce a whopping 47.3 feet per second and a head loss so high my tables do not show it. Whether or not your pump can produce that flow, the wear on the pump and every material involved just isn't worth it.

 

[Waterant]

head loss so high my tables do not show it.

Does it mean it will not pump the fluid high?
All 3/8" fittings are on the same level +/- a couple of inches.
Please excuse my ignorance if this is not what I think it is.

Whether or not your pump can produce that flow, the wear on the pump and every material involved just isn't worth it.

That pump was $106 ($125 now), and I will not cry when I have to replace it. plus, I plan to do this polishing for a couple of hours per season - i would not call this a heavy-duty usage.


but i get your point - for a new system, it may be better to go with a pump having a smaller flow more suitable for 3/8" return hoses?
the problem is, I could not find what that flow should be.

If I Google "What is the flow rate for a 3/8 hose?" I get "4-8 gpm".
it's not clear why, but even at 8GPM, it's still 480GPH and a huge improvement compared to 60-80GPH commercial polishing units which cost a couple of boat bucks or DIY systems with a toy fuel pump which will take months to transfer 300 gallons of fuel.

How do you calculate the maximum flow "allowed" for 3/8" return line without any "head" (vertical lift)?
Keep in mind, the intake is 3/4", and all the restrictions I could find were mostly related to the intake lines.

 

[HeadedToTexas]

Head in the context of pump performance is how high a pump will move a fluid and not the most meaningful variable when it comes to positive displacement pumps (like your gear pump) and this application. I used the term "head loss" which, in this application, is the sum of friction losses in the piping system. Total dynamic head would probably have been less slang-y and more technically accurate.

Any fluid flowing across a surface (such as the inside of a pipe or hose) creates some friction. That friction is a function of velocity and distance. The higher the velocity, the more friction. The longer the hose, the more friction. Pushing 15 gallons per minute through ⅜ inch hose produces a liquid velocity of 47 feet per second. Most engineers size hose for 5 or so feet per second or as high as 10-15 feet per second in some applications, but never 47 feet per second. Higher velocity is a problem because particles (the very particles you are trying to filter out) will create erosion problems.

The output of a centrifugal pumps (such as a bilge pump) is a function of total dynamic head. The higher the friction head, the less the pump delivers. You can find a pump for nearly any application, but it would take a ton of power to push fluid against the friction losses created by 47 feet per second.

Since your pump is a positive displacement pump and not a centrifugal pump, its output is far more constant. Unfortunately that means it will try like heck to push as much as it can through that ⅜ inch hose. The byproduct of that effort is pressure. The pump probably has a pressure rating that shows something like 15 gpm at 100 psi. Do you have a pressure gauge somewhere in your polishing system?

Did you measure that 15 gpm by filling a 5 gallon bucket in one minute straight out of the pump, or after going through your filters and ⅜ inch hoses?

Replacing the ⅜ inch hose with ¾ inch hose may not change the flow rate or turns of your fuel tank per hour, but it would lower the pressure on your system by lowering velocity and friction loss thereby saving wear on your pump and fittings. Of course, at $125, it might be easier to replace the pump every so often...

 

[Waterant]

Did you measure that 15 gpm by filling a 5 gallon bucket in one minute straight out of the pump, or after going through your filters and ⅜ inch hoses?

I measured the flow by filling a day heater tank. Everything is the same as tank polishing, but the 3/8 hose is only 4' long and not 25' as the ones going to each tank. It was a lovely flow, but I would not say it was anywhere near 100 PSI which seems like a lot of pressure.

when i have time, I'll take off 25' return line from one of the tanks and fill out a 5-gallon canister to see how long it will take. I feel like it will take around 20 seconds for 15GPM flow rate, but you made me curious enough to find out.
And also a pressure gauge on one of the return lines is on my never-ending to-do list now .

 

[HeadedToTexas]

Hehe, I can appreciate that!

 

[O C Diver]

Does it mean it will not pump the fluid high?
All 3/8" fittings are on the same level +/- a couple of inches.
Please excuse my ignorance if this is not what I think it is.

Let me help you a little bit. The 3/8" ID hose is your restriction. This is both by diameter and frictional line loss. The longer the hose, the more flow you will loose.

If you measure the inside diameter of 3/8" pipe, you will find it larger than 3/8". The restriction you have that can't be changed is the fitting into the fuel tank. A better approach would have been to come off the filter manifold with 1/2" or 3/4" hose, and only have the restriction going into the tank. You would have likely seen a significantly better flow rate with the larger hose, even though it went through a 3/8" fitting into the tank.

Mine is plumbed in 1/2" hose ,even though the flow is around 2.5 GPM. No flow loss and negligible pressure after the pump.

Ted