Fuel Polishing System

[noelex 77]

Originally Posted by osirissail

Using Racor 500's on such small engine systems is really overkill and a lot of wasted money. Racor 100 series would work better.
- - The Racor 500's Turbine filters need a significant fuel flow through them to activate the "turbine" effect for water separation.

There was a discussion on this a few months back. The conclusion was the water separation works fine (possibly better ) at low flow rates.

A larger filter will hold a lot more contaminates before it clogs and that seems cheap insurance to me, given the increased incidence of "bug" problems. As a bonus the elements tend to be cheaper than the spin on filters.

[Target9000]

I've been told the 500s will still separate at low flow rates as well. Does anyone have proof one way or the other? Link to the previous discussion?

[Target9000]

After going read the Racor docs it specifically says the "turbine" portion of the filter separates approx 30% of particles and "free water". Apparently the rest is done by the filter anyway. I couldn't find any mention of minimum flow to make full or best use of the filter, but I'd be interested in anyone that has test done to see how much difference the flow rate makes.

[emarine01]

Very good info Craig, EMDFUELS

[Florida Mike]

In all the information I find on fuel contamination it seems the main cause is the tank breathing during periods of nonuse. Has anyone ever thought of basically putting a balloon and check valve on the vent line, where the check valve would allow air in during fuel consumption and the balloon would allow for air to expand in the tank during the day and then put the same air back in the tank without any added moisture at night. And the only problem I see is during refueling you have to disengage the balloon somehow. I don’t think a birthday balloon would stand up to fuel fumes. I wonder if there is one that will?

Also my dead always had the fuel pickup extended to the bottom of the tank, his reasoning for this was get the credit out of the tank into the filters in small quantities instead of waiting for rough water conditions to stir the crud up. My two cents, Mike.

[DeepFrz]

In all the information I find on fuel contamination it seems the main cause is the tank breathing during periods of nonuse.

Until you can cite a credible source for this info you will not convince me of that. There will be very little exchange of air in most fuel tanks as most of them are at or below the water line. Possibly with the boat on the hard this might be a small source of contamination. A larger source of air intake into the fuel tank is when the engine is running. However, with a good fuel polishing system that has the intake and discharge tubes within an inch of the bottom (and using it regularly) you shouldn't have to worry about this at all.

[sabray]

I'd bet most of the crap comes from the station. Also I took quite a bit of water on deck my last trip. Looking at the fuel fills wile below an inch plus water I wondered how much water leaked past those seals. Would be a real good way to water down your fuel. I
Noticed while filling my water tanks on tank had a clogged vent. When the water was coming in small bubbles were forming at the cap so I probably have salt in my fresh water tanks. The cap looks fine and the o ring in good shape.there is a small crack somewhere in the key groove. Easy to fix maintenance item.I use a 2 micron filter on a very large 1000 series racor.lots of surface area. A smaller water separator after. Nothing is getting to the electric lift pump or the engines purpose mounted filter. Real big very fine filter and water separator and then fuel additives.

[DeepFrz]

Looking at the fuel fills wile below an inch plus water I wondered how much water leaked past those seals. Would be a real good way to water down your fuel.

Exactly! Those seals are very, very important as is making sure the cap is closed securely. A much better idea would be to have the fuel fills mounted in the side wall of the cabin. The only production boat that does this (that I know of) is Kadey-Krogan, although the newer Nordhavn may.

[Pete7]

Originally Posted by DeepFrz

Until you can cite a credible source for this info you will not convince me of that. There will be very little exchange of air in most fuel tanks as most of them are at or below the water line.

Nope disagree with that . A change in atmospheric pressure will move air in and out of an empty fuel tank as will a change in temperature during the day and night. The cooling effect of a steel tank containing moist air means water vapour will build up slowly but surely.

Little air will be drawn into our tank during use because we only use a couple of tank fulls a year on a yacht though clearly anyone using a motorboat will use more.

One of the reasons I changed to a plastic tank on a previous boat and I will swop the current steel tank out in time.

Your point on seals is very true and I suspect often overlooked. I took a while to work out why the previous owner had a small jar of petroleum jelly in the gas locker nearby the fuel filler.


Pete

[DeepFrz]

Pete7,
What was the daily temp. range of your fuel tank and how much change in temp of the fuel/air in the tank? How much air would be exchanged?

How much air moved in and out of the tank during atmospheric pressure changes?

Why do you think a plastic tank will have less air moving in and out during atmospheric pressure changes?

Was there any chance that water (either rain or sea) could have made it into your tank while fueling or while under way in heavy rain or heavy seas?

Inquiring minds, you know... ;-)

I actually think that a very small amount of water could condense into the tank, but I don't think that minuscule amount is the cause of most people's difficulties. Steve D'Antonio (man, I quote him a lot) has stated that one of the reasons (and a significant one) for replacing steel fuel tanks was because they rusted out from the top. The main reason for this was leakage around the fuel fill because of the seal at the deck becoming faulty. That seal is usually much more robust than the little o-ring used in the fuel fill cap.

[hummingway]

I've spent the last couple of days trying to get a good system worked out to clean the fuel and effectively "vacuuming" my tank. Really I'm just using a pump and filter setup with a hand held wand. I quickly got most of the water out of the tank, there wasn't a lot of it but there was some, a cup at most. I've gotten a couple types of algea, a white one that seems dispersed somewhat in the tank and a slime that seems to be mostly in the lowest point. In addition there is a dirt, slime and metal filings mixture at the lowest point. My tank is aluminum so I'm guessing the filings are from when the tank was first fit.

[DeepFrz]

Is the slime a dark color? If so put a drop of household bleach on a blob of it and see if it changes color. If it does its biomass.

Do you see any asphaltene? Maybe the "dirt".
Fuel School: Asphaltene's and Plugged Fuel Filters

Another thing that is becoming worse since low sulfur fuel was introduced.

[hummingway]

The description of asphaltenes makes me think it wasn't that. IT didn't seem oily so much, though being in fuel oil maybe my assessments not going to be accurate. Some of the slime was real algea like in the sense that it had long strands, or chains of cells. Some of reminded me of slime you get in ponds, again very algea like. I seemed to get most of that out but if I get more I'll do the bleach test. Some of the dirt was just plain dirt, tiny granules of grit mixed with bits of aluminum. I didn't get all of it yet but did get most. The white flakes were interesting, mostly little pieces but there were a few that were the size of a dollar coin.

I've started using both algea agents and lubricating/conditioning additives as a routine precaution.

[DeepFrz]

White flakes. Aluminum oxide?

[hummingway]

I'd heard of white algae in tanks and was guessing that was what it was. It didn't look flakes of oxidization. The bigger pieces were flexible.