Re: the positioning of a fuel pump in line between the tank and filter. I don't think this is a
good idea. Many of the pumps out there will not deal with the crud that may come out of a tank.
This crud could clog up a fuel pump and stop it from operating prior to the fuel reaching the
filter. Even though electric fuel pumps were primarily made to push fuel rather than suction it.
It is still wiser in this set-up to put your pump after the filter. This will ensure the fuel to the
pump is clear. The better setup would have two rather large Racors with a valve to switch from
one to the other if one gets clogged. Another idea would be to put a pump bulb between the tank
and filter and this would let you purge the system when needed. Ala no electric pump, wiring, or
attendant cost or reliance on yet another electric device that may only be used to prime fuel
anyway. The pump on the engine is a good and proven desin and its not a bad idea to carry a
spare pump or kit for this item. I would spend the extra money on a large filter and keep my tank
and fuel clean.
I pump the bottom of my tank with a hand pump every spring to rid it of any sediment or
water and from time to time pump the tank out through a filter and into a drum then clean the
tank bottom by hand and then filter the fuel as i pump it back into the tank. I've had great
success with this system and it's not too hard to maintain.
Bob S/V Bright Star March 2001
One detail to work out, which may have been mentioned, is the return from the engine high
pressure pump. Which tank(s) will it go to and will one tank be drained and returned to another
Recirc pump. Sarah, a T-37 in the slip next to us, does the recirc routine with their tank. Rough
days they turn on the pump and filter the tank as it is churned up. They use a gear pump for
recirculation with a Raycor 500 at the suction. The gears do not become gumed by diesel as a
diaphragm of impeller would. http://www.reversopumps.com/ has gear pumps which are
marketed toward the diesel market. The diaphragm version of this pump is sold by west marine
in the catalog.
Joe Sprouse Sojourn February 2002
Rich & al,
I am getting ready to redo the fuel system on Traveler. I would like to have a recirculation
system and a day tank that will provide a gravity feed to the engine, but would also like to keep
the system as simple as possible and use the parts on hand as much possible. My initial plan is to
use my Racor 500 on the suction side of a transfer pump (probably from Bosch) for the
recirculation system. I intend to draw the fuel from the bottom of the tank. I have a smaller Racor
that I plan to use between the day tank and the engine. I already have it and this sounds like the
best place to use it.
Would this arrangement be worth the trouble or should I go with the sort of system you
There are a lot more details such as transferring fuel from the main tank to the day tank and
being able to switch between the two and I'm currently scheming on them. I would appreciate
any thoughts fro m you or the rest of the list on this.
Coleman Blake Traveler February 2002
I installed a separate onboard recirculation (polishing) system: Walbro 12v transfer pump +
10µM (98%) polypropylene depth media filter (Osmonics Hytrex) in a polypropylene filter
housing in a pressure mode (not typical poor performing vacuum mode) filter system. I have an
iron tank which was severely contaminated with rust and organic particulate. I currently now run
the outlet dip tube at the VERY bottom of the tank to ensure particulate and free water removal.
The present pressure filtration system emulsifies (bad) any free water and the next future
step/addition is a simple **empty** filter housing with a clear plastic bowl and a drain cock
preceding the pump - this should trap most of any free water. All of this is mounted nearby the
Once you get inside any tank and do a mechanical cleaning (scrubbing, sanitization of
microorganisms, etc.) any recirculation filter system will keep the particulate well under control,
even in a large seaway wherein the fuel is severely 'sloshing' around. The pump is wired into a
vacant circuit breaker on the main panel, turned on anytime in a seaway and the engine is
running. The filter change out is based on increasing pressure differential (via a gauge); once
the tank is mechanically cleaned you probably won’t see any pressure change for a LONG time
when using an onboard recirculation / polishing system. The principal is that a 10µM (or larger)
filter will have a % reduction of particulate less than the 10µM rating and will essentially leave
the residual particle levels in the tank to less than 1µM after turning the tank over several times;
using a high flow rate filter the tank will 'turnover' faster with less amperage draw on the pump.
I've checked a correlation to the residual particle levels by optical density measurement methods
and can validate the less than a 1µM residual claim. If you use the common garden variety of
filters - Gulf Coast, etc. you will have to use a 1 or 2µM filter and suffer vastly reduced flow;
personally I'd stay away from those filters advertised and recommended on the "trawler world"
and other bulletin boards, etc. Obviously with such clean fuel in the tank, my Racors just simply
sit there with no challenge on them. I run a standard 2µM preceding the lift pump of a Yanmar
About 50% of what I do professionally involves critical micro-filtration and my 'slant' on the
filters typically used on boats is "snake oil" and 75-year old technology. I don’t use biocide
because I always drain (suck) any water from the tank, as my dip tube is at the very bottom. I
also seal the tank vent from atmosphere when storing the boat over winter, etc. to prevent
condensation on the tank walls. After I install the water 'knock-out' pot, the next project will be
to install a 3-4 gallon day tank (super clean fuel storage) so that if everything fuel related fails,
including the lift pump, I will be able to operate for a short time.
Rich Hampel wrote: February 2002
I'd disagree with putting any fine particulate retention filter on the suction side of a transfer
pump. Simply use a coarse screen (in accordance with the pump specs. + many transfer pumps
already have an integral screen already installed). Any filter run in vacuum/suction service will
have a **magnitude less** service life than a filter in pressure service. A pressure system in
which the filters are running on positive pressure is always vastly better in retention efficiency
and service life than a vacuum system.
I'd also fill the day tank with a filter and would not have any filter between the day tank and
the engine pump (other than the required secondary 2µM filter.... and that would be a redundant
'last chance' filter with a 2µM somewhere upstream). My perception of a proper day tank would
be a few gallons storage with a the input and outlet on the top of the tank (storage only)... thus if
any component of the pump system fail all you'd have to do is open a parallel cock at the bottom
of the tank, open a vent cock and simply drain the already filtered day tank to the injector pump
– nothing mechanically moving.... at least if the injector pump was still operating you could run
for several hours in an emergency. It would possibly require a 'momentary' air bleed on a
Yanmar to get it started (of course I'd have a petcock mounted so that I wouldn’t have to screw
around with wrenches in bleeding the air) although my 3QM30 will take a few slugs of air and
still start - not sure about a 4-107 Perk that requires a high rate of recirc fuel. A few electronic
differential pressure switches mounted in the system would all that would be need to
continuously monitor the *P across all the filters and primary pump(s).
Rich Hampel February 2002
Sid, I had a problem with 100 gals. of contaminated fuel. I purchased a portable diesel 12 volt
pump from a fuel oil company. I removed the manhole cover on my V-berth tank, inserted the
pump hard suction wand into the low detent and put the nozzle (like a gas station nozzle) back
into the manhole and ran the pump 3 times for about 1/2 hour each. The pump has a 35 gal. a
minute pumping rate, and has a in line filter cartridge. I used a 10 micron filter and in less than 2
hours had nice clean fuel. (I had also shocked the fuel with fuel stabilizer and bio-guard first)
The pump was about $230. and can be used as a emergency transfer pump as well as a annual
portable fuel conditioning pump.
Chuck "Sirena" February 2002
No.... the cooties are already in the fuel.... and they use the iron as a nutrient source. Best way
to keep them under control is a separate recirculation filter @ 5-10µM.
Rich Hampel May 2002
Subject: Cleaning fuel tanks
You can clean it out by hand then scrub all the internals with a long handled bronze wire brush.
The very best method however is to remove/dispose of all the oil, mechanically remove the 'crud'
as best you can, then use high pressure steam to blast the 'crud' and particulate off the walls to
the bottom, etc. Then *polish* the new fuel in the partly cleaned tankage to remove any residual
Polishing is recirculation of the fuel from the tank back to the tank, typically through a 12-volt
transfer pump, then through a 10µM or 15µM Filter, thence back to the tank. The relatively high
value of µM retention filter will allow a more open flow from the pump due to less internal
resistance (differential pressure) which will enable relatively high flows of recirculating oil
through the system and the filter. The recirculation total volume would be in the magnitude of
1000 gallons total filtered, although you would only have 50 gallons in the tank.
Since, for example, the 10µM filter typically has a % removal in LOWER retention (i.e. 20%
removal a 2µM, 5% at 0,5µM etc.) at each pass through the recirculation system you will get a
statistical removal of very small particulate. Consider that if you recirculate the oil 25 or 50
times, then the statistical reduction comes close to 100% of ALL particles, including
submicronic particles (including bacteria). Such 10µM or 15µM filters are quite inexpensive - in
the range of USD $8.00 for a 2.75" diameter X 10" length filter. The transfer pump that I use is a
Walbro 12 volt Fuel Transfer pump from www.belgoes.com (no longer a good link – try
http://www.kaydonfiltration.com/ )..... they also sell filters; but, not GOOD filters.
Most broad-based marine services usually have polishing systems mounted on a cart and can
do this service dockside.... but they charge a humongous amount of money to do so and usually
don’t leave the recirculation system on long enough to get down in to the truly "removal of
essentially all particulate" range. You can make such an 'onboard' recirculation system yourself
and every time you take on new fuel or if the sea conditions are rough ..... simply turn on the
onboard recirculation system to keep the fuel clean. My system sits in one of the bins just aft of
the fuel tank and is mounted on one of the mini-bulkheads.
I guess what I'm saying here is that there are professional services that will clean your tank for
you and they are quite good. However you can build (probably for less than a single professional
dockside polishing) for yourself your own system, and that system can become a permanently
mounted on-board process system to prevent FUTURE trouble. There are several websites
devoted to fuel polishing (trawlers, etc.) that you can do a web search for info, but from my
professional purification background... those websites are selling snake oil. The techniques
therein posted are OK but the equipment and most of the products that they pander are worse
Glad to hear that you had no rust inside the bottom of the tank. Consider taking a small mirror
on a long handle and go in through the limber holes that drain UNDER the external surfaces of
the bottom of the tank and inspect the underside of the tank.... as that's where most of the
corrosion and rust is usually found.
Rich Hampel September 2002
Check out "Gas Boy " portable transfer pumps at their web site: www.gasboy.com/
I purchased their 600 series pump (comes either 12 or 24 VDC) and just stuck it in the tank
manhole. It's rated for 20 GPM, so I let it run for about 30 minutes and did it 3 times, so I
figured I polished my fuel pretty well. It can also be used as an emergency onboard fuel pump
for other vessels either giving some fuel or taking on fuel. Cost was about $235 and it comes
with a canister filter. Cheap, quick, and best of all, it does a great job.
Chuck "Sirena" September 2002
For those of you with Perkins 4-108 diesels, what size micron, final fuel filter do you use? 10,
5, 2, or what? I currently use 10-micron but am considering changing to 2-micron.
Doug Coleman September 2002
The complicated answer is: Industry convention is that prefiltration stages are 5 times as large
in retention than the following stage filter. The final stage filtration should be 1/5th
(SMALLER) of the diameter of the most critical orifice (or equivalent) in the engine. "One fifth"
is historically chosen because particles tend to 'clump' together and 'bridge' .... so that its
probable that 2µM particles will block a 10µM orifice (or equivalent).
My Yanmar uses a 2µM as its integral final stage. I prefilter to 2µM so that I never challenge
the engine's integral filter with debris. Filter systems should be sized so that ALL filters (pre and
final) fail simultaneously - for economy purposes and so that you are not replacing 'uncompleted'
filters. The surface area (larger is better) that you choose is just as important as the 'micron
rating' ..... although a dirty filter is more efficient than a new filter.
The resinated paper filters commonly used on boats are typically 90-95% efficient in removal
at the advertised size rating, translating in 'absolute' terms:.... a paper 2 micrometer filter
probably approaches a 10 or 15 micrometer 'Absolute' rating.
IMPORTANT ..... Be very careful with manufacturer's "micron size" ratings..... as they are
'arbitrary' ratings assigned by the filter manufacturer and bear NO relationship to what is the
actual retention !!!!! .... as they NEVER state the removal efficiency at the 'size rating' which can
be anywhere from 50 to 97%. Stick with the leading 'brand names' (Racor, Fram, Purolator, etc.)
and don’t buy CHEAP.
Rich Hampel September 2002
Ray & al,
I don't know how I'm going to clean my fuel tank except that it's going to be a mess. I have a
simple fuel filter with an 80-mesh filter from McMaster-Carr. I'm going to use this and my fuel
pump (a KR12-40 from Belgoes - it's their upgraded replacement for the Walbro 68XX series.)
to try to get as much of the gunk off the bottom of the tank. I'm going to insert a length of tubing
through the dipstick hole and try my luck. The main goal of this operation is to inspect the fuel as
it goes through the filter globe and remove enough water and crud so that the fuel won't clog the
yard's heaters. If this is the case, they will pump it out for free.
Once the tank is empty I'll probably use some version of the Long Armstrong Method to swab
down the inside of the tank.
I'm thinking of replacing the dipstick with a length of tubing with a removable cap. The
hydraulic lines from the auto parts store look sturdy enough. When the vacuum gauge on the
Racor indicates that the filter is clogging up, I'll switch the pump inlet to the dipstick, go after the
stuff in the bottom of the tank and then replace the filter. Someone suggested that I have a few
inches cut from the bottom of the tank so that it wouldn't rest in bilge water and coating the tank
(it's aluminum and fairly new) with coal tar epoxy. Does anyone have any thoughts on this?
Coleman Blake Traveler T-37 # 328 November 2002
Cleaning the tanks is on my list this winter too. I was wondering how you are going about it?
A lot of paper towels and long arms or what? My arms aren't long enough to reach around the
baffles so I'm trying to engineer a way to do it. I ran down the fuel on purpose this summer and
will pump the rest out into cans. Then I'll see how far my arms reach once the inspection port is
off. Any ideas?
Also, about the recirculation pump. I like the idea and will probably put one in too but I was
advised by a friend who is a very knowledgeable mechanical engineer and world cruiser that I
should not waste my money because the engine pumps much more fuel than it uses and therefore
polishes the fuel just by running the engine. If you have refrigeration and are living aboard
cruising it my not be necessary to install a separate polishing system since you will be using the
engine many hours a day. On my friends 80-HP Westerbeke, he says he pumps 10 gallons for
every gallon burned at cruising speed. He feels this is sufficient to polish the fuel. Combine that
with a gauge for the Racor filter and even if your filter gets a little dirty, you know when to
change them by the flow meter. If I had dual Racor filters so I could A/B them to clean one off
line, like he does, I too would feel comfortable with not having a polishing system. The point I
find interesting is how much fuel goes through the fuel return line back to the tank.
Ray Slaninka Red Bank, NJ November 2002
Part of the grit may be the remains of deceased cooties. Making sure only clean fuel goes into
the tank is a necessary first step in making sure only clean fuel goes into the engine. We also
have a large Baja filter and all the fuel that goes into Traveler will go through it first. West
Marine has come up with new design that improves on the Baja. It was one of Practical Sailor's
picks of the year. If we didn't already have the Baja I'd get one.
I'm installing a recirculation/polishing system on Traveler. It only requires one valve and a
little extra plumbing. I hope to finish the job this weekend and I'll let the list know how it works.
This system will allow me to remove the water that will inevitably get into the tank (water
always wins) as well as the corrosion products and cooties that develop as a result. As part of
this operation, I'm going to clean the tank so we'll get a fresh start.
Coleman Blake Traveler T-37 #328 November 2002
If the gunk in the bottom of the tank is "gritty", I would be surprised if it was related to algae
or bacteria growth. Gritty, granular stuff is usually corrosion products from your tank or the one
at the marina or sand that gets carried in with the fuel.
The only way to reduce these types of things (you can not ever really eliminate them) is to
reduce water in the fuel and filter the fuel going into the tank (I would use a big Baja filter
funnel, especially if the marina does not adequately filter their fuel at the pump). I always ask
when the spin-on filter on the pump was last changed. I have not had to clean the tanks on
Magic Dragon yet, only having owned it for a year. I will probably sample the tanks this winter
to decide if I need to clean them.
Our last boat had about 1/4" of oily black residue on the bottom of the aluminum tank. I left it
there, because it would have been a big PITA to remove and the Racor filter did a good job of
removing it slowly. I never had a problem with filters plugging. This was with 20 years of
weekend and seasonal use only.
Frank Timmons V-42 "Magic Dragon" Deltaville, VA November 2002
I posted your very helpful drawing of your double fuel filtration and polishing system on the
Tayana ftp site. It can be viewed at
ftp://tognews.com/Rich_Hampel's_Fuel_Filter_System/ . I'm sure that others will find it as
helpful and informative as I did.
regards, Harvey September 2002
I especially refer to the 'toilet paper' filters, paper napkins and "Bounty' rolls. Toilet paper,
etc. is just a loose 'felt' of fibers, not resin bonded and is subject to release of fibers and
accumulated debris under increasing differential pressure. At increasing differential pressure
they tend to "unload" the trapped debris, thus capable of sending a 'storm' of previously captured
particulate and fibers down stream. Cellulose is a fairly good filter media when constructed of a
technical grade (ie. all fibers of essentially the same diameter, etc.) and especially when
'resinated' to hold all the fibers together. However toilet paper, etc. is made from cellulose that
has quite random sized fibers, etc ....... ****and is made to fall apart especially in septic tanks
and cesspools when water wetted*** - do you know of any fuel tanks that do not have water in
them? These Trawler world folks use the following report of their test methods: "The fuel was
crystal clear !!!" Hell, the very SMALLEST particle that you can see with the unaided naked
eye in good strong white light is 40+µM, lower than that you need an optical microscope (which
can only see down to 5 micrometers) and you need to have the particle backlighted, or a laser
particle counter, or a scanning electron microscope, etc. or some correlation of such
instrumentation; ..... certainly not some 'instant expert' with an unsubstantiated claim trying to
sell you something. This is absolute (100%) snake oil being offered (huckstered) to the gullible.
Where in hell is the Consumer Protection Agency or the FTC ????????????
The "Ametek" type housing is a generic polypropylene housing that is offered by essentially
ALL filter manufacturers. For fuel oil purposes it rates just barely OK as such a filter housing
holds the filter element in place by compression between the housing bowl and housing head.
One of the MOST important aspects of filter housing is its ability to seal the filter edges to
prevent BYPASS of particulate. The problem with such housings is that you can inadvertently
not correctly position the filter element within the housing thus never accomplishing the correct
edge seal that 'bites' into the end of the filter cartridge; or, the filter element can change
dimensionally as the filter media shrinks or swells. I offer that this Ametek type is the bare
*minimum* to seal versus greater than 1-2 micrometer particles. The very best housing and
filter system for fuels involves a filter that has its own end caps of either polypropylene, etc. or
stainless steel and most importantly uses o-rings that fit into a cup in the housing (piston seal),
etc or are a self contained system that include all these attributes - Racor type. Next best is a
double open ended filter cartridge that is positioned with a tie rod and a nut mounted in the
housing with a flat polymer gasket 'glued' to the ends of the filter cartridge. A filter cartridge
mounted in an integral polymer cage and end caps and fits into a piston cup with double O-rings
is the best .... but you're talking mega bucks for this type.
Trawler world and linked websites that offer such filtration, etc. are resurrecting filtration that
was abandoned long ago when it was validated (repeatable and validatable testing) that they
performed so badly; their only characteristic is CHEAP AND DIRTY. Please be advised that a
manufacturer or filter distributor can arbitrarily rate the retention rating of any filter.... and that
does not necessarily mean anything close to the actual (100%) rating. Filtration efficiency
(weight percent removal) is NEVER included with such filtration. If they were truly honest and
listed the actual efficiency, you'd NEVER buy them. Instead, they list baseless claims,
misdirecting testimonials, slick mumbo jumbo - snake oil .... especially since a 'consumer' has no
possible way to validate the ratings nor the efficiency. When you buy any such filtration
(protecting a $6000 engine) be sure to have the supplier list in writing the removal efficiency (in
weight removal percent) and see what happens.... Commercial Filtration (Racor), Fram,
Purolater, etc. will gladly advise with documentation and test methods, .... the snake oil artists
will have no idea what you’re talking about. Compressed pubic hair probably can accomplish
10% efficiency !!!!!!
The type of filter housings that you see at the Trawler world sites, etc. involve restraining the
filter cartridges with sharp edged cups that compress / bite into a (soft) end cap of the filter. They
are notorious for bypassing as the whole isolation of the upstream fluid from the down stream
fluid is totally dependent on the 'knife edge' seal. In industry they are usually only found on
filtration systems that remove: "rocks stick and feathers" - this type of filtration was essentially
abandoned in industry in the 1950s. The tie rod types are usually only good for filtration of 2 to
5 micrometers and above. The Integral O-ring types can accomplish filtration in the nanometer
range. ......... its all a question of BYPASS of particulate at the end cap of the filter.
Toilet paper probably 5-10% efficient (35¢), String wound: 60-70% ($1), Compressed and
resinated fibers 80% ($3). Spun bonded polypropylene and resinated cellulose 90-97%. ($8),
Pleated thermally set polypropylene fibers: 99% ($30). Sintered stainless steel micro fibers and
powder 99+% ($300). Polymer membranes: 100% ($150-250).
BTW: Kotex pads jammed into an empty filter housing filter better than toilet paper.
So where does one get such filtration? Go to your yellow pages or industrial directory and
look up a distributor of filtration offering: Osmonics, Fram, PTI, Pall, Millipore, Mykrolis, Cuno
, Commercial, Meissner, Sartorius, etc. ..... all 'front-line' and reputable filter manufacturers (but
some also sell 'string wound', so be careful). .... discuss with an application engineer your
application ....... and be sure to ask for the removal efficiency. The probable BEST (economy
and SAFETY) choice of filter housing is constructed of carbon steel with a TIE ROD and EPDM
gaskets. When discussing your application be sure to advise that you intend to filter diesel fuel
so that the application engineer can make the necessary corrections for the viscosity of diesel
fuel. If you 'engineer' you own system be advised that the volumetric flow values of most pumps
and filters are based on the viscosity of WATER and need to be corrected for diesel fuel
viscosity. When you buy a transfer pump, etc. be sure to ask if the open "flow rating" is for
water or for diesel fuel.
"Ya usually gets what ya pays for" ......... what’s the price of a new injector pump or a set of
injectors? when the filter train is totally 'slimed' and you’re drifting towards a lee shore and the
crew is so seasick that the sails cant be set.
Rich Hampel September 2002
Harvey, Thanks for posting Rich's schematic.
Rich, In an earlier part of this thread you stated that Belgoes does not sell good filters. Were
you referring to the Gulfcoast filter (GC-F1) (described in the Trawler World article by Capt.
Will at: www.trawlerworld.com/ ) which apparently uses a roll of Bounty towels as its filter
element? Can you comment on the efficiency or efficacy of this filter? It certainly has appeal
from the cost standpoint. Also, can you give us a source and model numbers for the "Ametek"
type filter housing that you are using. And thanks for the good info on fuel polishing...its my
Jim Smiley (T37 SMILES) September 2002
I don't usually point out inaccuracies in public chat but in the case of the discussion of light,
particle sizes and size of observable items, I have to state that you are incorrect. Light scattering
in liquids is used in the scientific community to detect particles on the order of the wavelength of
light. In the observable region of the E-M spectrum, 0.70um, one can easily, by naked eye, see
the light scattered by particles less than one micron in size. Thus, if the diesel fuel looks clear
with no hazing or light scattering, it sure is clean.
Another point, with an optical microscope, using oil immersion lenses, the scientific
community can see objects on the order of 0.20 microns. This is how biologists take those nice
color photos of bacteria that are 2.0 microns in size. One does not need to use an electron
Finally, I just can't seem to get into this discussion of filters. Any person that spends thousands
of dollars on their boat and also on purchasing fuel should be buying first class filters to protect
their investments. If they are not, then they should not be on the water - they are a hazard!
Jim Clemens s/v Athena September 2002
Subject: Re: [tayana-list] Cleaning Diesel Tank
Hell, the very SMALLEST particle that you can see with the unaided naked eye in good
strong white light is 40+µM, lower than that you need an optical microscope (which can only see
down to 5 micrometers) and you need to have the particle backlighted, or a laser particle counter,
or a scanning electron microscope, etc. or some correlation of such instrumentation; ..... certainly
not some 'instant expert' with an unsubstantiated claim trying to sell you something. This is
absolute (100%) snake oil being offered (huckstered) to the gullible.
Rich Hampel September 2002
Well, being one who uses optical, etc. methods on a regular occurring basis to validate
correlations to micro, ultra and nanofiltrations, separations, etc., I’m gonna tell ya back that oils
do not have the background transmissibility to the same level as an aqueous solution. The
difficulty in transmissibility with oils is the naturally occurring optical density "striations" and
other optical anomalies due to dissimilarities of optical density (locally and on a macroscopic
scale) probably due to the presence of emulsified, free, etc. water. Only if the residence
background is of **significant %** will one by an unaided eye discern (subjectively) ANY
particulate the difficulty of analysis by such optical methods (unless using a Laser Particle
Counter which accurately measures particles one by one) is only by correlation and for my 2¢
doesn’t come close to the real count. So the question back at ya is how is it that those using such
optical methods to count the density or magnitude .... can never agree even using the same
instrument and the same sample !!!!!!
BTW.... those photos of 2,0µM bacterial were done because someone trapped them on a
nuclear membrane filter disc .... otherwise they never would have found one by optical methods
unless by happenstance!!!! My workaday world is very deeply involved in 'particles' , bacteria
and such. ..... but we're going exponentially tangential away from 'boats' at this point.
Rich Hampel September 2002
A record of the differential vacuum will tell you when to change filters, and long before the
filters fully plug with crap.
Periodically make a record of the hours of engine time (or gallons) versus the increasing
vacuum on the gauge with the engine running at a specified rpm - i.e.: 2000 rpm.
With enough data points (time vs. vacuum) you can plot a graph. Most of the graph will be a
straight line that climbs at a constant angle over time. But as the filter begins to become clogged
you will notice that the plot will show a more rapidly increasing vacuum, and the plot will start
to climb (exponentially) and the straight line now will begin to 'curve' upwards. Typically when
the plot begins to 'curve' upwards you have about 10% capacity left in the filter and need to
change it. The graph will give you a historical record for comparisons later on of how clean the
contents of the fuel tank is, etc. OR if you notice that the vacuum has dropped - it means the
filter has broken and is now allowing particles to pass through the broken media or you have
developed a suction air leak in the piping. OR if the life is short and the straight line is quite
steep, then you can predict how much larger in surface area you will need (without cleaning the
tank or polishing, etc.) to last between routine maintenance.
The ONLY way to monitor the performance of a filter is with a pressure or vacuum gauge.
Rich Hampel September 2002
My fuel line is blocked between the tank and the Racor. Was told I ought to replace it with
rubber hose and forget the old metal one. Tank is under V-berth. Racor is on bulkhead under
cockpit. Any thoughts?
Both annealed copper piping and USCG approved Type A1 flexible fuel hose meet
ABYC/NFPA standards. Copper piping is typically more difficult and expensive to install. It can
also develop leaks due to corrosion, vibration (metal fatigue), etc. Flexible hose is subject to
chafe. If you choose flexible hose, be sure to buy USCG approved Type A1 hose (marked
accordingly along its length) for its resistance to fire and permeation. Secure/support fuel
distribution and return lines as needed, e.g., every 12-18 inches, to prevent chafe/metal fatigue
and physical damage.
Bluetango October 2004
The prices for the filters being discussed seem very high. Check the actual flow rate required
for your engine. There is little sense in having a filter designed to handle 500 gallons per hour,
when you have an engine that only consumes 0.75 gallons per hour. (That appears to be the
typical fuel consumption of a T-37 with a Perkins. I understand that the 30 HP Yanmar uses even
less fuel per hour). However, the calculation should also take into account the fact that fuel flow
is much higher than fuel consumption, as diesel engines return a major portion of the fuel back to
the fuel tank. The rule-of-thumb formula given in the Boat/US catalogue is
engine h.p. X 0.36 = fuel flow
(g.p.h.) Using the Perkins 1-408 as an example, the H.P. is about 50. Thus, 50 X 0.36 = 18 GPH
The smallest Racor filter listed for Diesel handles 15 GPH for about $75. This would probably
be plenty, but to play safe, you may want to go to the next size up, which handles 30 GPH. This
accepts the R20 replaceable filter, which is 2 micrometers pore size. The price on the 30 GPH
unit is about $100, and the replacement paper filter (R20) element is about $7. A canister filter
bracket for the Wix or Fram is about $25-$30. The filter is about $8-14, depending upon the
brand of filter selected.
Rather than dwelling on deciding about which overly expensive oversized fuel filter to choose
(at $750!), you would be best advised to put in the proper size unit, but do it sooner to protect
your engine, and for a total cost of about $130. Since most boats probably already have some
portion of the system installed, it may only require adding the extra Wix/Fram unit.
regards, Harvey March 2003
So.... Where can one buy the manifold with the nifty valve without the bigger filters?
Bruce Pappas March 2003
I made mine! Lucked out and talked to a local free lance mechanic who just happened to have
some left over manifolded Racor filters "from a power boat" in his garage. I bought them both
for $75.00 with home made valving to create the bypass set up. I also purchased a new filter
vacuum gauge from Racor. I spent something like $160 and wound up with the equivalent of the
approximately $700 + unit. It works great too! I don't have the fancy single lever valve but
properly labeled the switching of the 4 valves is very straight forward and painless. I can do it in
about 10 seconds.
Materials are 2 Racor filters and 4 ball valves plus hose and fittings for set up. I mounted mine
on some scrap 1/8" aluminum plate in the engine room with the gauge on the interior near the
nav station. I have not had a plugged filter since but when it happens all I need to do is flip the
valves to the 2nd filter position and then change the first filter element so I'm ready to switch it
again the next time the flow gets restricted. We have bars to cross in Oregon and don't need a
clogged filter giving trouble at the wrong moment there.
Jeff Leech Orca V-42 CC March 2003
Forget RUBBER tubing! There is NO rubber on earth that will last more than a several years
in this service. The only other polymer alternative is PTFE tube and that deforms and comes
loose over time. Go to an automotive supply store and get stainless tube, a tubing bending tool,
****a flaring tool and flare fittings****. Avoid 'compression' fittings like the plague as they
ALWAYS eventually loosen and suck air. You will have to make a very accurate cut across the
tube or will need to 'dress' the tube end carefully with a file before flaring.
Rich Hampel October 2004
The service life of USCG Type A1 fuel hose is typically in excess of 10 years, if not subjected
to battery acid/fumes or physical damage. Since stainless tubing is not ABYC-approved
(probably due to its propensity to corrode/pinhole in the marine environment) for use in fuel
distribution systems, it's likely to garner adverse comment (including a recommendation for
replacement) during survey inspections.
Excerpts from ABYC H-33 (Diesel Fuel Systems) are appended below. A copy of the
complete standard can be purchased/downloaded at www.abycinc.org
Susan Canfield Aeolus/T37 #-305 Annapolis, MD October 2004
Specifications are usually obsolete the day after they are written.
The UL 114 Marine hose you list contains Buna rubber and a balata/'cotton duck'
reinforcement layer ..... which has been obsolete in industry for similar service by about 15
By today’s standard, industrial standards (especially the more commonly accepted EU
standards), EPDM replaces EPR rubber which long ago replaced Buna (which replaced
What I recommend parallels the SAME tube and arrangement that is ALREADY on the high
pressure side of the injector pump - solid stainless with flare (or banjo) fittings. For flex joints
either SOLID 450 degree or 810 spiral return bends reduces virtually all propensity for cold
working. For short length flex connections either aircraft grade bellows (or link folded metal
tube ..... or EPDM hose with stainless external woven armoring is preferred .... as would be
consistent for most US Navy installations on prime movers. This is the typical compliance
approach for aircraft.
Copper reacts with the sulfur and oxygen in diesel fuel to form copper sulfate (thus corrosion)
when in the presence of water emulsions; and, is renown for fatigue failure (especially the
annealed grades). Just look at ON THE ENGINE OEM fuel delivery componentry --- would not
be compliant by ABYC if added as a retrofit !!!!
Rich Hampel October 2004
While I will agree some specifications are obsolete they day after they're written (ABYC H-33
was last updated in 1998), I suspect you'll find that UL 1114 - Marine USCG Type A)Flexible
Fuel-Line Hose - pre-dates the development of Type A1 and A2 hose, and may have been
referenced in H-33 in error.
ABYC H-33 and the National Fire Protection Association Standard for Pleasure and
Commercial Motor Craft (NFPA 302, also last updated in 1998) permit the use of Type A1, A2,
B1 or B2 hose under specified conditions, e.g., inside or outside the engine compartment, etc.
Surveyors inspect to both ABYC and NFPA standards. While Type A1 hose didn't exist when
most of our boats were built, I'd certainly recommend its use (in lieu of any other type of flexible
marine-grade hose) when OEM hose is due for replacement. Type A1 hose typically meets SAE
I'm well aware that stainless tubing is used for high pressure fuel lines on engines, that's why I
look at them closely for evidence of corrosion during survey inspections. I recommend
you discuss your views with ABYC's Technical Director, John Adey, at (410) 956-1050 or
email@example.com. The next revision of H-33 can't be far off.
Sue Canfield Aeolus/T37 #-305 Annapolis, MD October 2004
You're both right, use the SS tubing for the long straight runs and rubber hose in the bends and
at the points of vibration.
Despite the essential appeal of this rather Solomon-like approach, it would be better to use all
USCG Type A1 hose or all stainless steel tubing with a flex section at the engine, thereby
keeping the number of fuel line connections to a minimum. Most fuel system leaks develop at
Bill McMullen October 2004
Here's a summary repeat:
20µM particles are designated as the 'most damaging' to injectors, pumps and other engine
components. A 30µM filter probably only filters to 50-100µM on a 100% basis, a 2µM probably
A typical prefilter (primary) should be about ~5 times the retention size rating of the final
(secondary). If you have a *clean* system and tank, a 2µM will be quite adequate, protected by
a 10µM and the 10µM protected by a 30µM (they dont make 50µM). If your system and tank is
dirty use a 10-15µM as the final filter.
If for some reason you are changing from a larger retention to smaller retention, and the
original system is performing with adequate on stream service life, INCREASE the surface area
of the new smaller retention filter. Running a high vacuum across a small retention size filter
will/can break or wear out the diaphragm in your lift pump. LARGER surface area is 'always'
better; buy the 'largest' filter that you can fit. If you are running and the filters clog, don’t change
to a smaller retention sized filter; but, change to a larger sized filter (and suffer the wee bit of
extra engine wear) but at least it will take more time for the larger filter to 'choke'.
Monitor your fuel filters with gauges, so you know WHEN to change them. Run the engine at
WOT - wide open throttle, note the gage pressure when the filters are new and periodically
monitor the increase in pressure change over time.
Rich Hampel Ty37 #423 "Aquila" November 2005