Filter Element, 5 Micron to small?

[David van den Burgh]

Ariel originally had the same setup as Mahalo - Racor R24s as primary, and the engine mounted filter as secondary. Not only is the Perkins secondary a pain to change, as Rich mentioned, but it is essentially useless behind the 2 micron Racor.
Our new system consists of two 500FGs in series, the first 10 microns and the second 2 microns. By changing the filtration order, we progressively filter the fuel, prolonging filter life and - hopefully - reducing the possibility of a completely clogged filter. The engine mounted filter is still pointless, but bypassing it is more trouble than it's worth right now.
There are other benefits, of course, with the new system: fuel polishing circuit, larger and less expensive filter elements, easier to change and service.
The new system has served us well for the last two seasons, filtering out some serious crud while keeping the old Perkins chugging.

OJ: We relegated the old R24s to backup duty, as you describe, allowing us to switch between the primary circuit (the two 500FGs) or the secondary circuit (the R24s). Should the primary circuit need service, we switch to the old R24s, change the 500 FG filters, and switch back without interrupting engine operation.

[Tom in Cambria]

Another possible reason for two filters in series is that the old Fram used a two part filter element that was a particle filter on one side and a water separator on the other. The water separator never filled up or wore out but the particle side would. Thie two part fancy filter element ran around $20 to replace. Although I never did it, I considered putting a particle filter in front of the Fram that used an inexpensive element. By changing the cheap one frequently you extended the life of the expensive element which now only had to filter out what got past the cheap filter element. It would also be easy to change compared to the Fram. FWIW

[John Vigor]

OJ, the simple answer is that the first filter should take out the biggest lumps in the fuel, and the next filter should take out smaller lumps, and so on down the line, until you have left only the size of lumps the engine can swallow whole without burping.

I can see your confusion. There is no point in having a 2-micron primary filter if the secondary and third filters are are also 2-micron or more.

The only possible excuse for a 2-micron primary is that it will take longer to clog entirely, because its surface area is much larger than the surface areas of the smaller filters embedded in the engine.

Logically, of course, that renders any 2-micron filters after the primary unnecessary because nothing larger than 2 microns will get through to them, but logic isn't always rampant among sailboat owners, as you must well know, otherwise we wouldn't own them.

John Vigor
CD27 "Sangoma"
Bellingham, WA

[Cathy Monaghan]

Hi Pete,

I have a Racor 500 as my Primary filter. How small of a filter element can I get away with (or should)? Example, "Will a 5 micron just starve the engine or be fine for fuel flow but gunk-up (technical term ) up to quickly?"

There are several threads about multi-configurations of filters in series to address cleaning fuel. But I did not see any clear, this size works well, better, best, etc.


Thank you,

P.S. My engine is a Univ. M25

For what it's worth, my husband and I attended two engine maintenance seminars while we were at Sail Expo in Philidelphia this past January. One was given by Mack Boring (Yanmar) and the other by Westerbeke. The persons giving each of the seminars recommended to NOT use a fuel filter less the 10 microns. They recommended between 10 and 30 microns.


Fair winds,
Cathy
CD32 Realization, #3
Rahway, NJ
Raritan Bay

[s.v. LaVida]

OJ,

You are correct, in the best of worlds, you should be able to bypass a clogged filter and run on the back up, by having the proper valving to divert the fuel flow to the "clean filter". A system that allows you to isolate the clogged filter "on the fly" and replace it is very handy indeed.

As mentioned in other posts, gauges on the inlet and discharge side of the filter are very handy in telling you the flow state of the filter.

IMHO, the first line of defense is to make sure your tank is fuel tank is clean to begin with. Many boats (that only use a little bit of fuel per season) have healthy buildups of deposits on the tank walls. At the first sign of rough weather it breaks loose and winds up in the filters, with the predicticable results of clogging everything and shutting down the engine, usually at the most inopportune time. (I speak from practical experience, on this subject.)

So, a good cleaning of the fuel tank(s) is a wise move, hauling the tank out of the boat and having it steamed cleaned is the best method, or you can hire a fuel polishing contractor and/or install a recirc system .

I use a good biocide to help prevent the sludge in the first place and in any suspect fuel areas I also use the Baja filter to separate any possible water and or dirt out of the fuel.

However keeping all water out of the fuel is almost impossible. Any partially filled tank will have condensation in the tank due to daily temperature variances. Over time this can really add up and contaminate good fuel.

On LaVida, we use a Racor 500 and a separate recirc system. In addition we burn so much fuel through LaVida in a season, that there is always a fairly fresh load in the tank, along with a healthy dose of biocide.

fair motoring!
Mike

sea u,
Mike

[Kurt]

I've read many posts about crud build up in fuel tanks. So when I repowered my 1980 CD27 last year I made sure to remove the fuel tank and clean it. Much to my surprise, there wasn't much crud in the tank at all! I simply poured some Electrasol dishwasher soap into the tank along with a couple gallons of hot water and let it sit overnight. The next day I took it to a do it yourself car wash and rinsed it out with high pressure hot water. It came out looking like new on the inside. The previous owner did use a biocide in it regularly over the years and was careful about where he purchased his fuel so that seemed to pay off in the long run.

[Tom in Cambria]

Cathy: Did they say WHY nothing smaller than a 10 micron filter element? I've heard this from time to time, but never the rationale. Why does Racor even make a 2 and 5 micron element if you're never supposed to use them? And how did we get by for all those years with those 1 micron Fram elements that Cape Dory put on our boats? Has the state of knowledge improved since Cape Dory was making our boats? Just Wondering.

[Tom in Cambria]

Kurt,

When I cleaned my fuel tank it didn't really look dirty either. I had a very thin layer of slime for want of a better word. I could drag my finger through it and leave a clear path behind. I thought at the time that it might just be the biobor lying on the bottom and sides. It was enough to stop the engine every few hours though. Apparently a badly contaminated tank doesn't look any worse than a can of cream soup after you pour the soup out. The fuel isn't really milky looking or anything like as bad as that. At least it wasn't in my case.

[guest]

Hi All

Using new lap top so I hope this goes.

I use a 2 micron filter and change it twice a year . I change it just before I go out in the bay of Fundy just in case there is some rough weather and there is some sludge in the tank

Phil Shedd
Gamblin CD 31 25

[Bob L]

I have a Westerbeke 21A and it has 2 filters on the engine. Those, in additon to a 2 micron RACOR 500.

Bob

[Ed Haley]

OJ:
John V. has it right about filters in series. In fact I use the same setup in my house for filtering water. I have a sediment filter (for larger particles like silt, sand, etc) that is inline with a charcoal filter that removes smaller particles and most of the chlorine/fluorine taste from the cold water tap in the kitchen sink. They last about 2 years before I notice a change in water pressure or bad tastes coming back. If we just had the charcoal filter we would have to change much more often when we'd notice a pressure drop in the water.

Same thinking on the reasons for 2 or more fuel filters in series. There is just more mesh area provided for filtering. The fuel supply provided to the injectors would have less of a chance to be interrupted when gross sediments from the tank enter the line. They would be trapped by the first filter (which allowed smaller particles to pass through) and thus not clog the smaller mesh filter(s).

[bottomscraper]

Cathy: Did they say WHY nothing smaller than a 10 micron filter element? I've heard this from time to time, but never the rationale. Why does Racor even make a 2 and 5 micron element if you're never supposed to use them? And how did we get by for all those years with those 1 micron Fram elements that Cape Dory put on our boats? Has the state of knowledge improved since Cape Dory was making our boats? Just Wondering.

Melissa and I attended the Newport Boat Show this weekend where Mack Boring was doing a seminar. The justification for not using 2 micron elements in the secondary was that it put extra strain on the lift pump.

(Note this post has been corrected, I originally had my primary & secondary confused. )

[Cathy Monaghan]

Hi Tom,

Just so no one is confused, I'm talking about the Racor filter and not the filter that's on the engine itself or the primary filter. The Racor should be 10 or 30 microns.

Cathy: Did they say WHY nothing smaller than a 10 micron filter element? I've heard this from time to time, but never the rationale. Why does Racor even make a 2 and 5 micron element if you're never supposed to use them? And how did we get by for all those years with those 1 micron Fram elements that Cape Dory put on our boats? Has the state of knowledge improved since Cape Dory was making our boats? Just Wondering.

I'm no expert but I believe the rationale is that if the pores in the filter element are too small, especially if it's the first filter in a series of filters after the fuel tank, that nothing will get past it, not even the good fuel. And, as Rich noted, there's extra strain on the fuel pump if the filter pores are too small. You want to filter out the larger particles first so that you still get fuel to the next filter. The fuel should be pretty well filtered by the time it gets to the engine's filter or the primary filter which can be a 2 micron filter.

You'll find more info on this subject at the Torresen Marine web site. And take a look at this Bootkeeper article by Terry Johnson, "Fuel Filters: Choose Well and Prosper".


Cathy
CD32 Realization, #3
Rahway, NJ
Raritan Bay

[Ed Haley]

Perhaps the use of the words primary and secondary might be confusing when describing fuel filters. Perhaps the following might help.

[img]http://www.imagestation.com/picture/sra ... 3f3e5f.jpg[/img][/img]

[Bob L]

I used to use a 10 micron racor filter. When I did this, the primary filter (closest to the injector pump) would be black when I'd change it. Switching to a 2 micron racor resulted in a reasonably clean primary. I figure that if the primary clogs and I need to replace that filter, it'll take a while longer than to replace the racor. Also I figure that I'd rather have a second line of defense, so to speak, to protect the injectors from this crud.

A few years ago I had my tank cleaned which helped cut down on the crud.

Bob