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Question about Racor filters

AXEL

.
Mar 12, 2008
359
Catalina C30 MKIII WEST ISLIP, NY
Which Racor fuel filter/water separator for Universal M25XPB?
Specifically which flow rate and filter size (microns)?
Thx
 
Jan 27, 2008
2,983
ODay 35 Beaufort, NC
I used a Racor 120 for years on my M25, you will only burn about a gallon an hour so the required flow rate is pretty low. I put in a new fuel tank a while back and upgraded to a 500MA for increased filter capacity but the 120 was fine. I use the 120 as a fuel polishing system so I can pump out the tank periodically into jugs to clean it (the tank). And also to filter new fuel going into the tank. 10 to 30 microns is fine for your primary filter. The secondary filter (the one on the engine) should be the one with a smaller micron rating. A micron is .000039 inches so 10 microns is .00039 inches. A human hair is about .003 inches in diameter just to give a feel for the particle sizes involved.
 
Feb 14, 2014
5,216
Hunter 430 Waveland, MS
A human hair is about .003 inches in diameter just to give a feel for the particle sizes involved.
Cigarette smoke is 10 micron.:cool:
For the diesel fuel rate of my 50HP and we purchase from a fuel source that has pre-added biocide, we use 10 micron.
Your filters will NOT remove dissolved water.
Jim...
 
May 20, 2016
2,976
Catalina 36 MK1 94 Everett, WA
My understanding is that the primary (racor) should be 2 micron and secondary 10 microns. Seems backwards but found that combo documented too many places.

I've also read that the 2 micron filters are only 98% efficient at removing 4 micron particles. A holdover for when they used different standards and test methods.
 
Feb 14, 2014
5,216
Hunter 430 Waveland, MS
Seems backwards but found that combo documented too many places.
That documentation seems suspect. More likely some one trying to sell you an unneeded secondary filter. How would a 10 micron particle pass through a 2 micron? If the particle is gelatinous, your pump will starve before squeezing through.

If you buy the centrifugal water separation type filter, 10 micron is more than adequate for a good diesel fuel pump.
Jim...
 
Feb 6, 1998
11,347
Canadian Sailcraft 36T Casco Bay, ME
Even the smallest Racor they make will exceed what you need in flow rate so no worries there.

Westerbeke/Universal (Bob B. & Joe J.) advise a 30 micron primary if the fuel lines are longer than 10' and a 10 micron primary if the filter is less than 10' away. They suggest not to use a 2 micron..... I replace far more lift pumps on boats with 2 micron filtration that I do on boats with 10 or 30's....

You'd be adding a lot of work to your lift pump if you were to choose a 2 micron. These engines are designed to run on the main on-engine filter which is (per Westerbeke's Joe J.) 15-17 micron nominal and approx 25 micron absolute. On boats we add an additional "primary filter" to aid in water removal and to add another layer of protection.

Unless you have a common-rail diesel there is no need for a 2 micron filter and it usually only leads to other problems. These engines really don't need 2 micron filtration, not even Racor advises it for this type of engine.

As an example our club launches (2 Westerbeke & 1 Yanmar) which run almost constantly from 7:00 am to 9:00 PM 7 days per week for almost 6 months per year, they run 30 micron primaries plus the standard on-engine filter. Two of these engines have now exceeded 10k hours.

If you had an on-board fuel polishing system, with a pump designed to handle 2 micron, than filtering the tank down to 2 micron is a perfectly fine practice. I won't personally install a 2 micron filter on the engine filtering system of our boat even though our tank is already 100% polished using a recirc system.

P.S. The primary filters Yanmar re-labels as "Yanmar" & sells for their marine aux engines, (re-labeled Racor's), are 30 micron....
 
Feb 14, 2014
5,216
Hunter 430 Waveland, MS
Unless you have a common-rail diesel there is no need for a 2 micron filter and it usually only leads to other problems.
:plus:
My diesel fuel is so clean, I plan to go to 30 micron after I use the 10 micron spares.

Moral of story: Clean diesel requires no filtration.;)

Jim...
 
May 24, 2004
6,635
CC 30 South Florida
2 micron for the primary is too restrictive in real life. Many of us perhaps to different degrees have some sedimentation in the fuel tank and all it takes is an offshore passage or some rough waters to stir them into the fuel and quickly clog a restrictive filter element. I had not thought about the added strain they may place on the fuel pump but it totally makes sense. We use 30 microns and when replacing our filters we usually find the secondary filter to be quite clean.
 
May 24, 2004
6,635
CC 30 South Florida
:plus:
My diesel fuel is so clean, I plan to go to 30 micron after I use the 10 micron spares.

Moral of story: Clean diesel requires no filtration.;)

Jim...
No fuel is clean, it is stored, transported and dispensed by, in less than ideally clean tanks and pumps. Diesel fuel is food for bacteria which will die and its carcass with thousands of others will settle at the bottom of the tank. That is the reason we require filtration.
 
Feb 14, 2014
5,216
Hunter 430 Waveland, MS
No fuel is clean, it is stored, transported and dispensed by, in less than ideally clean tanks and pumps. Diesel fuel is food for bacteria which will die and its carcass with thousands of others will settle at the bottom of the tank. That is the reason we require filtration.
Good reason to find a reputable diesel supplier that adds an algaecide.

BTW I do have a 10 micron filter for just such precautions. It has been 2 years since I changed one. I also have a Vacuum gauge on my filter to verify MY diesel is clean. A clear housing to visually check for water (also never had any in 3 years) and plugging filter with microbes (appear black specs)
For pictures see my post #6...
https://forums.sailboatowners.com//index.php?threads/fuel-line-maintenance.180546/

Jim...
 
Jan 30, 2012
1,054
Nor'Sea 27 - "Kiwanda" Portland/Anacortes
JIm et al

Dow has written a paper entitled Microbial Contamination of Diesel Fuel: Impact, Causes and Prevention.
It discusses this topic at some length and the conclusions are helpful to eliminate the many rumors and wife's tales surrounding this subject.

Search also for RichH (who is an engineer specializing in filtration) His posts have discussed filter size ratings (2,10,30 mic) how to set up your filtration for the best performance.

I can send the Dow article to those who are interested.

Charles
 
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