Fuel Filtration Systems

[gts1544]

Gentlemen:

On our Perkins 4-108 powered 41' Beneteau in the British Virgin Islands (read warm and moist), we currently have a 30 micron Racor 500 filter as the Primary and the Perkins #26561117 as our Secondary (Microns unknown). We do use Biocide with every diesel fill, but still have some contamination in the tank, which ultimately clogs the Racor after time. My question is whether I should go to the 10 micron Racor element to better protect the secondary filter or whether I should stay with the 30 micron so as not to have to change it so often? Any advice would be appreciated! gts1544 - George

[colemj]

Is your secondary also fouling at the same rate? If not, then stick with the 30um, although I personally prefer the 10um as a primary.

If the Racor is clogging frequently (more than once/year), then you should consider having the tank cleaned.

Mark

[gts1544]

Mark,
Thank you for your reply. We cleaned the tank several years ago (more than 5) as the 10 members had not been using biocide on a regular basis. After the tank cleaning, we began using it with every fill (I hope).

My problem was a badly surging engine, which I was able to limp back to our base mooring. Our regular mechanic came aboard and promptly changed out both filters (the Racor was definitely filthy) but I did not get a good look at the Perkins filter, so the result there is inconclusive, nor had I been monitoring filter change frequency, which I will now do. That definitely solved the surging problem.

Since I am the member responsible for the maintenance of the boat, I will confer with our mechanic to track the filter changes to see if a tank cleaning is necessary. I would prefer to use the 10 micron as the primary, but am concerned that the frequency of clogging would become too often.


Does anyone know the micron rating of the Perkins #26561117 Secondary filters?

Thanks again for your input!

gts1544 - George

[Wotname]

FWIW, I'd far rather have to change filters frequently than deal with the consequences of sub 30 micron particules getting through to the injector pump etc.

[Dockhead]

Have your tank cleaned, and be more careful about where you buy fuel!

I clean mine every two years.

If you're having chronic problems despite regular tank cleaning, then consider installing a fuel polishing system or at least, some other way to get fuel out of the bottom of the tank. A dip tube right down to the bottom of the tank (which we hope has a low point or sump in it) can be used to pull up samples from time to time and make sure you are not getting water or sludge accumulations.

This is not something to mess around with. If you don't keep the bottom of your tank free of water and sludge, you will have the following problems:

1. Sometime in bad weather when you really need the engine (keep off a lee shore; forereach under power; get into shelter), the sludge will get stirred up by the boat motion, and you will lose power, just when you need it most. Nightmare scenario.

2. The acid produced by the microorganisms will eat holes in your tank, requiring an expensive replacement.


This is not something to mess around with. If your filters are getting clogged, you have a much bigger problem than just choosing what kind of filter to use. Changing filters, and indeed, using biocide, is just treating the symptoms. To treat the cause, you have to keep the bottom of the tank clean and free of water, and have a way to know that it is clean. The bugs won't grow if there's no water to begin with -- the bugs are merely symptoms of a corrupted tank.

[gts1544]

Wotname,

Only the Primary Racor filter is 30 micron, while the Secondary Perkins #26561117 filter has a micron rating that is unknown to me, but certainly much smaller than 30 microns.

My concern is whether we are letting too much crud through the Racor (at 30 microns) that it will clog the Secondary too often. Currently anything smaller than 30 microns is being passed downstream to the Secondary, while if I went to a 10 micron Racor Primary, then only material smaller than 10 microns would be passed to the Secondary. I am open to any knowledgeable advice.

George

[sailorboy1]

Probably a better upgrade would be a vent line moisture filter system to keep water out of the tanks!

[colemj]

Secondary filters used on engines are typically 2-5um.

Mark

[Dockhead]

Originally Posted by sailorboy1

Probably a better upgrade would be a vent line moisture filter system to keep water out of the tanks!

Of doubtful value considering the small volume of air which can "breathe" through the vent. There were calculations made by people posting on this in other threads, showing the vanishingly small volume of condensation possible from tank breathing.

This fact was also used to debunk the myth that full tanks attract less water than empty ones. I believe MaineSail posted some really good factual data on this, IIRC.

[skipmac]

A really good upgrade to consider is a dual Racor system. The system has a valve that lets you immediately switch to the second filter if the first is clogging. Also has a vacuum gauge that will show as the filter in use is clogging.

[Dockhead]

Originally Posted by skipmac

A really good upgrade to consider is a dual Racor system. The system has a valve that lets you immediately switch to the second filter if the first is clogging. Also has a vacuum gauge that will show as the filter in use is clogging.

Indeed. And the dual Racor system also lets you change filters without shutting down the engine. I have a setup like this and a box of spare filters on board.

But if you have sludge at the bottom of your tank, and your filters start to clog, you will only get so far by changing filters. You can easily go through a box of filters in one storm, and then where are you?

These measures are all worthwhile -- good filtration, dual Racors, etc. -- but they are secondary to the main job of keeping the tank clean, and are no substitute at all for that.

[skipmac]

Originally Posted by Dockhead

Indeed. And the dual Racor system also lets you change filters without shutting down the engine. I have a setup like this and a box of spare filters on board.

But if you have sludge at the bottom of your tank, and your filters start to clog, you will only get so far by changing filters. You can easily go through a box of filters in one storm, and then where are you?

These measures are all worthwhile -- good filtration, dual Racors, etc. -- but they are secondary to the main job of keeping the tank clean, and are no substitute at all for that.

Absolutely. If you don't address the issue with the tank then all else is just putting a Band-Aid on a large, gaping wound. For me the main benefit of the dual Racor is the ability to do an immediate swap if the filter clogs at a very inopportune moment, like pulling into a dock or something.

[sailorboy1]

Originally Posted by Dockhead

Of doubtful value considering the small volume of air which can "breathe" through the vent. There were calculations made by people posting on this in other threads, showing the vanishingly small volume of condensation possible from tank breathing.

As a water treater who also deals with the water in fuel tank issue in industrial installations I disagree. The volume of air/water isn't really an issue, the issue is that it exists and happens.

But believe whatever you want.

[thinwater]

Originally Posted by Dockhead

Of doubtful value considering the small volume of air which can "breathe" through the vent. There were calculations made by people posting on this in other threads, showing the vanishingly small volume of condensation possible from tank breathing.

This fact was also used to debunk the myth that full tanks attract less water than empty ones. I believe MaineSail posted some really good factual data on this, IIRC.

Except the data and calculations were ALL INCORRECT! The internet is a dubious source of information.

As a licensed tank inspector and 32-year chemical engineer I can tell you that:

a. The most serious hazard to tank inspectors is falling roof bracing, damaged by underside corrosion caused by condensation.

b. Have done testing of atmospheric condensation in fuel. Though it does require specific conditions, it is reproducible. I published on this, with pics.

c. They skipped one rather obvious detail; if a drop of dew falls from the roof into the fuel, it is trapped and does NOT re-evaporate in the morning. It is a trap. Obvious, no? There are several mechanisms that were omitted.

The petroleum industry spends real money on desicant filters. Probably a forum of sailors knows better.

That said, leaking fuel fills are the leading trouble spot. Same with big shore tanks!

[Kenomac]

I did an entire thread on this subject a year ago. On the CF website search window type "fuel polishing system installation" then search by date 18-09-2014. If you decide to install a system, your problems will go away once and for all.

I just filtered my entire tank of 225 gallons of diesel purchased 9 months ago, and didn't get a single bit of contamination in the filters. The solution is a proper installation of a fuel polishing system that will remove the water and impurities throughout the season. Any other approach is just treating the problem after it occurs.

The system will pay for itself the first time you have contaminated fuel. There's no way to be careful where you buy fuel, even the best places sometimes serve up crap.