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Portable fuel polishing units

6K views 15 replies 10 participants last post by  Noelex 
#1 ·
A few weeks ago, there was a service guy at our marina with a portable fuel polishing unit that he brings to your boat to polish the fuel.
I didn't get a chance to talk to the guy but I would like to have it done to my boat.

Has anyone had any experience with this kind of service? Good, bad, depends on the service guy?

Approximate cost for a 25 gallon tank?
 
#2 ·
I had this done to a boat I just bought that had been sitting in the yard for 2 yrs. I had to sail it from Boston to Newport so did not want to take a chance with the fuel. I had only about 14 gallons in the tank and got estimates around $500, but shopped around and got it done for $275. Now that seems like a lot but they cleaned all the gunk from the bottom of the tank also. If you just have the fuel pumped out there is a good chance that the algae and gunk at the bottom of the tank will screw up your day when you hit rough water and things get sloshed around. I would reccomend it. I have had no problems and we ended up motoring a lot.
 
#6 ·
How are you cerain the tank bottom was cleaned? You wouldn't be able to see it, not really. Or is that the answer? On larger tanks you certainly could not, certainly not if using dyed diesel.

(I don't mean to be the kid we all hated, saying "how do you know?" to every statment as an empty and annoying challenge. I'm honestly curious.)
 
#3 ·
Getting a tank cleaned 'just because' is probably not worth it. You will wind up paying for something you likely don't need. On the other hand if you do need it, it can save a fortune in bloody knuckles, and filters.

The best way to check is just to open the inspection port on your fuel tank, and take a look around. If there is crud, or suspended solids its defiantly worth the money. If the tank is bright and shinny, there's no reason to worry about it.

I have had it done a number of times, and it's a pretty easy process. The portable polisher is just a high volume pump with a series of step down fuel filters. It just recirculates the fuel in your tank for a while until the entire tank has been cycled a few times. Ideally you use the return hose to agitate the tank a little to try and get the gunk off the bottom (same reason it's a high volume pump).
 
#4 ·
$250 bucks is a lot of money to me. What I did was pull the tank.
Drained most of it but left about a gallon.
It had baffles so I got about 5 lbs. of small chain, stuck it in the tank and swished.
I was amazed at what came out.
Repeated several times with clean fuel, until everything came out clean.
Happen to have a very large funnel, so using kitchen paper towels as a filter I was able to recover most of the fuel which appeared very clear, but decided to put it in my truck instead.
I installed a Racor and have not had any fuel issues.

Dick
 
#5 ·
I had it done on a 90 gallon tank that was not removable. They cut an inspection port in as well. The tank was scrubbed clean and about a half gallon of black goo was removed. The tank was 23 years old. I had lots of problems with clogging filters (even with dual racors) before the tank was cleaned. After no problems.....If you have inspection ports, try draining the tank and cleaning it out on your own. I don't think just filtering the fuel is enough, the tank needs to be physically scrubbed, rubbed and wiped out.
 
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#9 ·
As an engineer deeply involved in filtration engineering for over 35 years .... recirculation polishing of fuel without a thorough mechanical cleaning of the tank is of very little benefit.

Simple speak: If you dont get inside the oil tank and scrub the thick biological deposits from the walls, these 'agglomerated' bio-particles will continue to break off the walls and re-contaminate the oil, plus the cellular debris that does break loose only becomes the nucleation sites for even more growth of larger particles. Without a thorough cleaning of the tank walls, recirculation polishing of the fuel oil is only a very temporary remedy.

Most tank fouling is usually caused by a fungus - Cladosporium Resinae or 'kerosene fungus', etc., species that use the carbon content of oil as their nutrient source. It usually enter the tank through the VENT. Growth of such species is exponential.
How to know when to clean out a tank: remove some of the tank oil, put it into a clear glass container and hold it up between your eyeballs and a strong white light - if there is any 'haze' noted when you look through the oil to the strong white light, it means that the oil is fouled/contaminated and that the tank should be cleaned .... then the fuel should be 'polished'.
For the price of a single commercial 'polishing' one can easily build their own on-board polisher: a simple Walbro type 12 vdc transfer pump, a 10" steel filter housing, a ~15µM 10" X 2.5" dia. industrial resin bonded cellulosic filter .... just continually pump directly from the bottom of tank directly back to the tank. A good 'rate' for recirculation polisher is approx. 2-3 gallons per MINUTE per 100 gallon tank. If the system is 'clean' that 15uM filter operated anytime the engine is on will produce a particulate level at 'submicronic' levels, the oil will be 'crystal clear' (no haze) .... and there will be no challenge to the system's inline (Racor) filters. Any particles that do get into the tank will be constantly and quickly removed. Such a system is very cheap to use as you wont be changing out your racors all that often as the debris is removed by the 'cheapy' industrial filters in the recirc. loop.
Do NOT put an onboard recirculation polisher in/on the main fuel delivery system or its return line.

;-)
 
#14 · (Edited by Moderator)
Do NOT put an onboard recirculation polisher in/on the main fuel delivery system or its return line.

;-)
My fuel polishing system runs for several hours a day and I now have crystal clear fuel. The polishing system picks up from the bottom of the tank via its own pump, filter and line, but it returns via the diesel return line. I am curios why you consider this is a wrong ? I cannot see how it would create any problems.

The polishing system is only run when the main engine is off, if this makes a difference.
 
#10 ·
My tank does not have an inspection port. Can the biological deposits be washed off the walls using the transfer pump as a pressure washer?
 
#12 ·
Probably not.
Such deposits begin as living colonies with natural 'adhesives' to help them 'stick' to the surfaces. Its when the cells die and break off from colony or when large portions of the colony breaks away is when the 'trouble' begins. You really have to visualize to be sure of the complete removal; otherwise, its just a 'guess'.

You can use chemical tank cleaners such as: Star brite - Catalog - Product Detail .... but unless you direct visualize, you can never be 'sure'.

To lessen and minimize contamination: keep the MINIMUM amount of fuel in your tank; dont always 'top-off' as there is NO BENEFIT in storage of 'old' fuel; diesel and gasoline have relatively short 'shelf life' when in contact to atmospheric air); use 'fresh' fuel (from a high-turnover 'truckstop', etc.); drain/empty the tank when the boat is not being used for looooong periods such as winter storage.

BTW - Atmospheric water 'equilibrates' or 'saturates' into fuels (typically through the tank vent); the less amount of fuel - the less water 'uptake'. ;-)
 
#15 ·
By putting a recirc. filter in the injector discharge/return line, you change the parameters of the injector return pressure ... increasing pressure in the return line due to the pressure drop of the filter when clean plus accumulating flow resistance as the filter becomes 'loaded'. Such can cause an increasing 'rich' mixture for the injectors, in comparison to a discharge line that operates at essentially atmospheric pressure.
Since your system 'works', let it alone; but, if you later experienced a much high fuel consumption, this may be the cause -- recirc. FILTER becoming plugged with corresponding higher back pressure on the injector discharge line.

;-)
 
#16 ·
By putting a recirc. filter in the injector discharge/return line, you change the parameters of the injector return pressure ... increasing pressure in the return line due to the pressure drop of the filter when clean plus accumulating flow resistance as the filter becomes 'loaded'. Such can cause an increasing 'rich' mixture for the injectors, in comparison to a discharge line that operates at essentially atmospheric pressure.
Since your system 'works', let it alone; but, if you later experienced a much high fuel consumption, this may be the cause -- recirc. FILTER becoming plugged with corresponding higher back pressure on the injector discharge line.

;-)
Thanks for the answer, but I don't really understand it. The polishing filter is not in the return line. If the polishing filter was completely blocked the engine return would work normally.
The polishing system picks up from the bottom of the tank, to a pump, then the polishing filter. The polishing filter returns diesel to to tank via a T connection on the return line which is between the engine and the fuel tank.
The engine has a separate fuel pickup and filter, but there is only one return to tank which is shared by the engine and polishing system.

This is a common way of plumbing a polishing system.

Perhaps you are only warning about placing the polishing filter actually in the return line so all the engine return fuel has to go through this filter. This is different to engine and fuel polishing system sharing the return line. I can see how the former plumbing would cause a problem, but I have never seen a polishing system designed like this.
 
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