I need a "Filter Microns 101" Course...

[firstbase]

Trying to understand the fuel filters on my boat (twin Ford Lehman SP135s) and filters in general. As mentioned in a previous thread I have dual Racors that have 30 micron elements then two on-board engine filters with 5-7 microns. What I don't understand is why 30 micron in the Racors and why only filter down to 5-7 mics when 2 mics are available. It would seem that my setup allows a lot of "stuff" to get through to the on-boards which are more difficult to change out. Then there is stuff less than 5-7 mics that get into the injectors/engine. Is there a reason that I wouldn't want to get as much filtration as possible as soon as possible in the system? I know that filtering down to 2 would cause more frequent filter changes but...that would seem to be a good thing? What am I missing?

Thanks for any comments!

 

[dhays]

Trying to understand the fuel filters on my boat (twin Ford Lehman SP135s) and filters in general. As mentioned in a previous thread I have dual Racors that have 30 micron elements then two on-board engine filters with 5-7 microns. What I don't understand is why 30 micron in the Racors and why only filter down to 5-7 mics when 2 mics are available. It would seem that my setup allows a lot of "stuff" to get through to the on-boards which are more difficult to change out. Then there is stuff less than 5-7 mics that get into the injectors/engine. Is there a reason that I wouldn't want to get as much filtration as possible as soon as possible in the system? I know that filtering down to 2 would cause more frequent filter changes but...that would seem to be a good thing? What am I missing?

Thanks for any comments!

You can do anything you want and will get plenty of advice, some of it ignorant like mine.

It seems to me there are two camps to this continued debate on filtering. The first camp is the one in which I fall that says that you should filter the fuel as the engine manufacturer intended. Folks a lot smarter than I and with the appropriate engineering background came up with those recommendations for a reason. They also specified fuel filtration that matched the fuel pumps in the engines. So I would say look at your engine information and see what they suggest. If they suggest 30 micron primarily filtering with 5 micron secondary, then do that.

The other camp feels that, in general, you can't have too much filtering. If 30 micron filtering is good, 20 is better and 2 is best. They never want to touch their on-engine filter so want the primaries to do all the filtering so the on secondaries never get dirty. They distrust the manufacturing recommendations for a variety of reasons ranging from being too general and not specific to their installation (not a bad reason actually) to some vague conspiracy theories involving lawyers, filter manufactures, and black helicopters.

Nothing wrong with highly filtered fuel, but there are two potential problems I can see with using 2 micron primary and secondary filters. The first as you mentioned is more frequent filter changes. Not a really bad thing, but if your engine manufacturer doesn't care about particle size before 5 microns, do you need to filter down to 2 microns? The more important question is whether your fuel system can handle the added restriction of 2 micron filtration when it was designed for 5 micron filtration. It takes more effort to pump fuel through two, 2 micron filters than it would through a 30 and a 5 micron filter.

In the few minutes it has taken me to type this, I won't be surprised if you get 5-6 responses giving you 5-6 different answers.

To read something from someone that actually knows about what he writes, check this out.
https://www.sbmar.com/articles/fuel-filtration/
https://www.sbmar.com/articles/marine-fuel-filtration-the-seaboard-way/

 

[Bigsfish]

Lots of different theories. If the manufacturer goes to only 5 microns that is what would run as both primary and secondary, but he goes to 2 micron at any point I would run 2 micron filtration both on the primary and secondary as it will require no more suction or pressure than the lowest size filtration. I have a friend that uses Racors of 2 micron and changes the primaries (which are factor 2 micron filters) every ten years.

 

[firstbase]

Thanks. My understanding is that the FL 135's were manufactured for the 30 and then 5-7 microns that have been used. They have last 30 years and are in very good shape. Now they meet me. New guy who knows little to nothing talking about changing things. If engines have eeyeballs they are probably rolling back in their head...I think I just answered my question. Just trying to understand a little is all. I do think that the fuel flow is so low/slow on these that it would make little difference flow or fuel pump wise but its all those things that I don't know are happening that scares me away from changing. I believe Brian at American Diesel said if I wanted to go to 20 mics on the primaries then that would be ok.

Thanks for taking the time to respond. Now I am trying to figure out where the less than 5 micron stuff goes after it gets through. Brian also said that because the fuel pump is oil lube and not fuel lubed they don't get by. I have NO understanding of what that means and maybe I heard him wrong...

 

[ktdtx]

I believe part of it is the different requirements of the newer, electronic common rail engines which require better filtered fuel (2 microns) and the older systems which don't have the same requirements. BUT

I don't see any reason not to change the Racor to 10 micron and the on engine to 2 micron and provide "cleaner fuel" as long as the flow thru the filters is adequate.

And, there are smarter people than I who will comment here.

 

[dhays]

Lots of different theories. If the manufacturer goes to only 5 microns that is what would run as both primary and secondary, but he goes to 2 micron at any point I would run 2 micron filtration both on the primary and secondary as it will require no more suction or pressure than the lowest size filtration. I have a friend that uses Racors of 2 micron and changes the primaries (which are factor 2 micron filters) every ten years.

OK, a couple questions.

First, I don't know hydraulic physics at all. However, it would seem to me that you will get more resistance in a system that has two 2 micron filters in series than a system that has a 10 micron and 2 micron filter in series. Is this wrong?

Secondly.... I'm guessing that you misspoke when you mentioned your friend replaced the primaries every ten years and actually he replaces the on-engine secondaries every ten years? Given that, then I'll just remark that I've never owned a particular boat for more than 10 years. If your friend has only replaced his on-engine filters once or twice over 10 to 20 years, he might as well never bother replacing them.

 

[Lou_tribal]

One question, how old are you engines?

L.

 

[firstbase]

Lou, if that question was meant for me, the OP, they are 1987 vintage. 4,100 hours on them. Need to get them to 8,200 in the same shape. Just want to do what I can to make that happen. If that means leave it the same, fine. If I can help it by changing a couple of filters to be more efficient then that is great too. Just want to do things that actually help and don't just make me feel better.

 

[sunchaser]

FB

Four things

-- Go to boat diesel and read their fuel filtering articles
-- Second, educate yourself on what beta ratio means
-- Third, any filter when it starts out will only but "approximate" for it's listed micron rating and quickly start plugging up or going finer over time.
-- Lastly and for whatever it is worth, clean fuel turned over frequently trumps the normal fuel filter size discussions

BTW, my engines use a 30u primary and on engine of about 5u. Quite honestly, anything within reason will suffice for your application. Even what you have now.

 

[Capt.Bill11]

FWIW, for old school Lehmans I like you use Racor 900s with either 10 or 2 micron elements in them.

The 900s offer a very large increase in filter element surface area over the 500s.

 

[smitty477]

FB

Four things

-- Go to boat diesel and read their fuel filtering articles
-- Second, educate yourself on what beta ratio means
-- Third, any filter when it starts out will only but "approximate" for it's listed micron rating and quickly start plugging up or going finer over time.
-- Lastly and for whatever it is worth, clean fuel turned over frequently trumps the normal fuel filter size discussions

BTW, my engines use a 30u primary and on engine of about 5u. Quite honestly, anything within reason will suffice for your application. Even what you have now. h




That post +1....


ttps://www.sbmar.com/articles/marine-fuel-filtration-the-seaboard-way/

 

[Bigsfish]

Dhayes

"Quote:
Originally Posted by Bigsfish View Post
Lots of different theories. If the manufacturer goes to only 5 microns that is what would run as both primary and secondary, but he goes to 2 micron at any point I would run 2 micron filtration both on the primary and secondary as it will require no more suction or pressure than the lowest size filtration. I have a friend that uses Racors of 2 micron and changes the primaries (which are factor 2 micron filters) every ten years.
OK, a couple questions.

First, I don't know hydraulic physics at all. However, it would seem to me that you will get more resistance in a system that has two 2 micron filters in series than a system that has a 10 micron and 2 micron filter in series. Is this wrong?

Secondly.... I'm guessing that you misspoke when you mentioned your friend replaced the primaries every ten years and actually he replaces the on-engine secondaries every ten years? Given that, then I'll just remark that I've never owned a particular boat for more than 10 years. If your friend has only replaced his on-engine filters once or twice over 10 to 20 years, he might as well never bother replacing them.


As explained to me the restriction in flow can never be greater than the smallest filter size, so you can stack ten 2 micron filter and the glow will the same as one filter.

Second, correct I meant to say he replaces the primaries and not the secondaries I asked him why he even bothers to replace the secondaries and it said it made him feel better. LOL

 

[Comodave]

I don't think that the CAV type filters are available in 2 microns, 5-7 is what I have seen. I use a 10 micron in my racor 900s. I would rather change them several times rather than changing the secondaries once. Brian said no problem with this setup.

 

[markpierce]

Both my primary and secondary filters are two microns. That's how the boat was originally outfitted.

 

[Lou_tribal]

Lou, if that question was meant for me, the OP, they are 1987 vintage. 4,100 hours on them. Need to get them to 8,200 in the same shape. Just want to do what I can to make that happen. If that means leave it the same, fine. If I can help it by changing a couple of filters to be more efficient then that is great too. Just want to do things that actually help and don't just make me feel better.

So for the last 4100 hours in 30 years they have been working perfectly the way they are, I would not touch anything. If it was not the right setup your engine would not have last 30 years in perfect shape ( I assume they are ).
I hear your concern and I got the same, and reading things about fuel filtration setup and best practice just made me more worrying with all the expert advice about it. But I don't think that any engine built 30 or 40 years ago has the same requirements as contemporary engines.
But I am not an expert

L.

 

[Comodave]

Lehmans don't need 2 micron filtration since the injector tolerances are not as tight as the new common rail injection engines which have very close tolerances.

 

[kapnd]

Your fuel can never be too clean.
Do as Smitty suggested, and read up at boatdiesel.com, and sbmar.com.
Diesel fuel is formulated much differently today than it was when your engine manufacturer wrote his spec.
It is much cleaner in terms of emissions, but is now capable of carrying more water in suspension.
Your filtration needs to be up to the task by TODAY's standards.

 

[Lepke]

Final micron size is determined by the injector nozzles. Some have finer sprays than others. So the secondary filter needs to be at the manufacturer's recommended size or smaller. Common (at least in bigger engines) is 30 primary and 10 secondary.
I use 2 micron in my primary because of an issue with my boiler nozzle plugging. My Detroit mains together pump 75 gallons an hour and burn about 8. So the fuel goes thru the primary and secondaries many times. (like fuel polishing) The Racors catch about 90% of the water, but the secondaries will also trap about an ounce. I change the secondaries once a year. Mostly for the water they hold. A 2 micron filter lasts about 500 hours, changed when vacuum gets to about 7", but I don't buy fuel just anywhere.
Running a 2 micron primary keeps debris out of the fuel system and makes gears in my Detroit pumps and other fuel system parts last longer and the injector pumps in my generators last seemingly forever.

 

[Ski in NC]

I don't think it makes much difference at all. Use a 30, 10 or 2 mic primary, whatever makes you happy. 2 mic will tend to clog faster. And don't run your secondaries for ten years!!! Filters age. A couple of years, max on both primary and secondary.

Most of the stuff in our filters is soft bio goop or asphaltenes, none of which is particularly abrasive. Probably could run fine with no filters at all.

 

[Tom.B]

I need a "Filter Microns 101" Course...

Micron ratings can be fairly complex. It is imperative to know the efficiency (Beta Ratio) associated with the given micron rating. When a company publishes a micron rating without this information, it does not tell the customer how efficient the filter is at the given particle size. For instance, if Company X rates a filter at 15 micron, they may be referencing a nominal micron rating which could mean the filter is anywhere between 50% and 90% efficient at that particle size.

This might be more in Filter Microns 202, but here is some good reading material:

http://www.baldwinfilter.com/literature/english/10 TSB's/89-5R3.pdf

http://www.baldwinfilter.com/literature/english/10 TSB's/04-2R1.pdf

 

[winty]

No advise here, I'm working to better understand filtration as well.

I have a single Lehman 120, racor 900, duel CAV secondary. Based on the log and recipes over the past 20 years, a 2 micron filter has been used in the 900 (primary). I have continued to use the same 2 micron Racor filters. Boat carries 300 gallons, I burn 300 gallons a year, topping off in 75-100 gallon increments.

Primary filter changed every 400hrs. Secondary every 12-18 months. I have not experienced at shut down and I do not have a pressure gauge. My tanks are original and no clean out ports. The 900 bowl accumulates a good amount of black sludge over 400 hours, no water.

 

[Nomad Willy]

I started out w 2 micron filters.
Decided 6-7 years ago to use 30 micron.
Still think 30 is just fine.
Just an opinion.

 

[FF]

Our reason for using finer filtration than a classic DD 6-71 requires is why not?

Now that we can filter the fuel to a high standard , there is no extra work or expense , as our fuel tank is clean.

The filters are changed on time , the start of every cruse season , and have never needed a running shift from Raycor 1000 #1 to #2.

Remember the filter values are NOT absolute , a 2 will pass 20 or 30 chunks as well as smaller , but just not too often.

If you need to carry a case of extra filters , it is best to seal them before storing.

 

[firstbase]

Thanks for the very informative info and links. For now I'm going to sink the money into having the tanks cleaned and fuel polished (due to the original situation that started all of this). Can't see a clear cut reason for me to change anything at this point! Know a lot more about all of this now which is priceless.

Winty, keep the videos coming....

 

[smitty477]

"Primary filter changed every 400hrs. Secondary every 12-18 months. I have not experienced at shut down and I do not have a pressure gauge. My tanks are original and no clean out ports. The 900 bowl accumulates a good amount of black sludge over 400 hours, no water."


While changing filters is good changing them by hours of use is a bit arbitrary. Changing by gallons of fuel is a bit less arbitrary but there is no correlation to the amount of filtration plugged vs the filter change. Over time you will take on fuel that requires more or less filtration dependent upon the batch and over time your tanks may accumulate and disperse fuel with more suspended contaminants dependent upon sea states you are in.
Without a vac gage on your fuel filter the process of changing filters becomes a guess where it is equally likely that you will be changing out good filters or that you will be too late and perhaps lose fuel flow and affect an engine at a inconvenient time. The vac gages can also help diagnose and/or eliminate some more common engine issues. Reading the link posted will supply much more comnentary and pictures that can help describe fuel filtration

 

[Benthic2]

could too fine a filter over burden your fuel pump ??

 

[Nomad Willy]

Of course it can and then I would assume the engine quits.
But the real question is what's needed. If one actually seeks perfection in the question of the mesh of fuel filters do as Sunchaser says .. go to boat diesel.

 

[Heron]

I'm all for progressive filtering. My primary is a very large 27 micron Fleetguard, feeding into a 10 micron racor, feeding into a 2 micron engine filter. The fleetguard will literally catch all the crap without clogging, and the others downstream will provide clean fuel for the eventual burn...I rarely have to replace filters as the Fleetguard handles most of the bad stuff and still flows fuel..

 

[sunchaser]

I'm all for progressive filtering. My primary is a very large 27 micron Fleetguard, feeding into a 10 micron racor, feeding into a 2 micron engine filter. The fleetguard will literally catch all the crap without clogging, and the others downstream will provide clean fuel for the eventual burn...I rarely have to replace filters as the Fleetguard handles most of the bad stuff and still flows fuel..

Heron
Now this is a great setup. By the book, ready for a load of bad fuel (hoping of course it never happens) and with an easily changed fleet guard. What engine?

 

[dhays]

I'm all for progressive filtering. My primary is a very large 27 micron Fleetguard, feeding into a 10 micron racor, feeding into a 2 micron engine filter. The fleetguard will literally catch all the crap without clogging, and the others downstream will provide clean fuel for the eventual burn...I rarely have to replace filters as the Fleetguard handles most of the bad stuff and still flows fuel..

Very nice setup. I have never gotten a load of bad fuel but I think the idea of adding a course Fleetguard before the dual Racors would be great to have just in case.

I have a vacuum gauge on my filters and never have seen an increase in vacuum. I still will replace the Racors on the schedule I outlined above and replace the on-engine filter every two years unless indicated by vacuum or exceptionally dirty primaries.