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Go Back   SailNet Community > On Board > Gear & Maintenance > Engines > Diesel > Home Made Diesel Polishing System Q
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Thread: Home Made Diesel Polishing System Q Reply to Thread
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Topic Review (Newest First)
01-27-2010 05:23 PM
klem RichH,

I think the recommendations you made are very wise. In the end it should result in cheaper operation (Racor filters are expensive) and better operation due to the flow. I had forgotten to recommend a gauge in my post but they are very helpful.
01-27-2010 04:55 PM
RichH
Quote:
Originally Posted by xort View Post
Where would this screen be? In the pick up of the pump? It will need cleaning so make sure it's easily accessable and removable.

Since walbro said it's OK to put the filter before the pump I'd go that way.

The tradeoffs are that the screen will keep some of the gunk out of the filter ($) but you will have to disassemble the system to clean the diesel & gunk soaked screen often. How often? Probably a lot at first until you get the gunk out of the tank. Then it shouldn't be needed much after that.

Good luck
Screen - Its inside the covering/housing to the suction side of the pump.

Most debris in diesel fuel oil is 'soft and deformable' (cells and metabolic products/resins of or from funguses) and will get 'chopped up' by a 70µM 'screen' at increasing differential pressure.
If you have a supply source that 'particulates' a lot of hard particles (rust, etc.) then consider to apply a 'strainer' on the suction side of the pump.
01-27-2010 04:49 PM
RichH
Quote:
Originally Posted by cruisingmom View Post
Thanks folks for responding
I chose the Walbro because it was a marine rated diesel 12V pump with a separating screen filter on its intake for primary screening of junk (70 micron) prior to the RACOR.
Andy
Using a Racor in a fuel recirculation polishing system is a very expensive filter to use in a recirc. system. A Racor type filter is for removing a VERY small amount of debris from a relatively large system (0.005% or typically 30-50 GRAMS of crud is about all you get from the typical RAcor).

I'd recommend to
1. 'up' the throughput of the pump (typically 3 gallons per MINUTE per 100 gallon tank is 'reasonalbe'). The newer Walbro pumps are 'outstanding' vs. long service life.

2. Install a STANDARD INDUSTRIAL filter housing (industry standard is for use of filter cartridges of 10" length and 2.75" (or 2.5") outter diameter.
I'd suggest Shellco Filters Shelco Filters
Other: most industiral filter housing have 1/4" connection on the top/bottom of their housings
There are other manufactrers of industrial filtration products. Dont use HomeDepot stuff nor filters that are for home heating oil.

3. Use STANDARD industrial filter cartridges (available worldwide from zillions of manufacturers) Size the 'retention rating' @ 5X the retention of your FINAL filter in the RACOR Set (not including the OEM engine 'guard' filter. Choose a 'graded pore density' filter ('pores' get smaller as the fluid travels through the filter media). A graded pore density filter of polypropylene melt blown fiber should cost about $8 to 15.00 ea.
These are usually 'honestly rated' for their µM (nominal) retention; should be at least 90% retention at the indicated 'rating'. Avoid Home depot and other hardware store unbranded filters - as their ratings are very variable. ... you want 'quality' not cheap.

4. The recirculation system should be totally isolated from the standard fuel delivery system AND with an independent pickup tube AT the very bottom of the tank.

5. Run the pump BETWEEN the tank and the filter housing (pump PUSHES the oil). Therefore in PRESSURE MODE the pump will not 'stall' (no flow) until the pressure differential of 'crud' on the recirc filter is about 50 psig max. If you run the pump in 'suction mode' the pump will stall (at about minus 3-4 psi.
In pressure mode, if the pump inlet screen/strainer becomes 'choked' with (hard) debris you will begin to see negative pressure (or a drop of differential pressure) on the gage (see 5a.). Most debris in boat diesel fuel system is 'soft/deformable' (cellular debris of funguses, etc.) and the pump 'screen' at 70 µM will usually 'chop up' the deformables.
You will get longer filter life, more total gallon filtered with 'pressure feed' than with 'vacuum feed'.

5a. Apply a pressure gage between the pump and the filter housing. When operating compare the gage pressure to the filter manufactures "flow vs. deltP curve" to monitor the flow and to know WHEN to change the filter. You many want to use an electrical differential pressure switch wired to an alarm .... hi and LOW pressure switch so you know when to change AND for safety/enviro issues.

Dont get 'locked' into using one particular filter manufacturer because of 'geometry' - the worlds industrial 'standard' for filtration is 2.75" dia X 10-20-30-40 inch length filters. Cartridges with FLAT neoprene rubber endcap gaskets are suitable, so is 'knife edge' cartridge sealing for such fuel filtration.

Ive Been very deeply involved in filtration engineering for over 40 years. Racor makes the BEST filters for the PRIMARY fuel line filtration. NOt worth it for 'recirculation-polishing' filtration. Parker(Racor) has industrial filter divisions (and distributors) that can fill your needs if you somehow need to stay with the Racor brand.
Dont buy from an industrial supply source that requires a 'minimum charge'.

:-)

hope this helps.
01-27-2010 07:29 AM
xort Where would this screen be? In the pick up of the pump? It will need cleaning so make sure it's easily accessable and removable.

Since walbro said it's OK to put the filter before the pump I'd go that way.

The tradeoffs are that the screen will keep some of the gunk out of the filter ($) but you will have to disassemble the system to clean the diesel & gunk soaked screen often. How often? Probably a lot at first until you get the gunk out of the tank. Then it shouldn't be needed much after that.

Good luck
01-27-2010 06:52 AM
cruisingmom
Final selection for fuel pump and process

Well folks - just thought I would share what I have learned. Spoke to the head engineer at Walbro (fuel pump manufacturer). He recommended that I purchase the FRB22-2 to attach to the Racor 500fg. He thought that using before the filter would work and that the screen sediment filter on the pump would act as a prefilter, but also understand me wanting to filter first - either way this was acceptable to him. He said that this pump would have similar turn over pumping as the racor not to exceed 55 gph. He also said that while corrosion resistant he felt the advantage was that it has a smart spring assembly that results in less than 1.0 amp hour of power draw during use so that it was quite 12V battery friendly.
I have found out that the Whitby 42 fuel tanks (port and strbd) have only 1 large baffle in them so that aggitation with either a clean air line or manual method may get the stuff stirred up, and that the pick up line on the Whitbys are above the bottom so that I will need to aggitate the fuel to get all the bottom crud off. So that is what I will be setting up. Hope this helps others and thanks for all the input
Andy
01-25-2010 11:37 PM
xort Lehmans return quite a bit to the tank so you are polishing whenever you run the engine.

How about running a compressed air line down the fuel filler hose to agitate the tank?
01-25-2010 09:42 PM
cruisingmom
Thanks Folks for thoughtful input - here's some update

My engine is a Ford Lehman 80 Hp Diesel (4D254 - 2712E). I also have the ability to pull from one tank and return to another. I just bought a used Racor 500fg on e-bay for $51.00 so I thought I would split the fuel line going from my tanks to the main RACOR 500fg and have it go to a ball valve that I can open and attach to this new Racor 500fg then to the Walbro marine diesel pump and then back to a fuel tank (through the deck fill port). At 35-40 gph I can leave it run for several hours and turn over the tank several times. I agree that without agitation I will not get the crud off the walls, but hopefully I will be able to clear the lines of crud and at the same time remove any water from the tank. MY thought is to make this mobile unit set up so that I can do both tanks in the spring, and then also a tank after agitation at sea.
The Walbro pump was $120.00, so for about $200 I can make a separate polishing system that will not gunk up my primary Racor (hopefully) and can help to maintain the cleanliness of my fuel and tanks over time.
I guess I am trying to be belt and suspenders since I filter all fuel prior to adding in the tanks, but I know some water condenses during the cold maine winter and also there is some gunk build up at the tank t valves.
Andy
01-25-2010 03:12 PM
klem
Quote:
Originally Posted by SeaFever2000 View Post
Andy,

What kind of an gine do you have? The reason I ask is that some of the diesels have a bleed valve and you could do some fuel polishing in a economical way by leaving the bleed valve open a bit.

I have a Universal M25 and I leave the bleed valve open 1/4 turn all the time. Hence when the engine is running the excess fuel is continuously running through the system (hence also the Racor 500FG) and being dumped back into the tank. Yes, this method does not take care of the crud at the bottim of the tank, but I thought I would mention it. I figured this out when I had the engine in my garage and actually saw what leaving the bleed valve open did to the working of the fuel system. Just a thought.
Leaving the bleed valve open will lower your fuel pressure which is not ideal. Diesels already return to tank using an overflow valve. Typically around 90% of the fuel is returned to tank so it is already accomplishing the flushing that you are referring to.

If I was starting with a clean slate, I would filter all my fuel before putting it in the tank and then have 2 filters in parallel (racor makes some units that do this) allowing you to change either filter without shutting down the engine and pay for someone to polish the tanks with the proper equipment only when I had known contamination. Everyone has their own preferences but that is what I would do. It is not particularly applicable to the OP because they have a known issue in one tank and need it polished.
01-25-2010 03:09 PM
jrd22
Quote:
Originally Posted by SeaFever2000 View Post
Andy,

What kind of an gine do you have? The reason I ask is that some of the diesels have a bleed valve and you could do some fuel polishing in a economical way by leaving the bleed valve open a bit.

I have a Universal M25 and I leave the bleed valve open 1/4 turn all the time. Hence when the engine is running the excess fuel is continuously running through the system (hence also the Racor 500FG) and being dumped back into the tank. Yes, this method does not take care of the crud at the bottim of the tank, but I thought I would mention it. I figured this out when I had the engine in my garage and actually saw what leaving the bleed valve open did to the working of the fuel system. Just a thought.
Most diesels that I'm familiar with (unfortunately I am not familiar with the Universal) return some fuel to the tank continuously when running through a return line (do Universals not do this?).

We have two tanks and a dual Racor filter with separate supply and return lines to each tank. I can draw from one tank and return to the other if I want, thereby polishing the fuel from one to the other. This does not agitate the tank and remove the gunk in the bottom though unless it's very rough while motoring, and it takes a long time (days) running to move any significant amount of fuel so it's not really very effective at polishing. I could install a pump (other than the electric primer we have) and with the addition of a couple of valves and a little hose I could run it through the filter and polish from one tank to the other.
01-25-2010 02:42 PM
motion300 Here is what I have learned... If your fuel has sat a while( I don't know long, maybe a year) and you mostly sit on your boat, there is probably gunk in your fuel and If Murphy and his way and he always does you could have a problem. This will only happen when you are 20 miles offshore in 10' seas or trying to dock your boat in stiff winds with the whole marina watching Your motor will quit or at least do no more then idle rpm. You will probably knock off your bow sprit or at least damage your neighbors gold plater. From what I can learn , a proper fuel polishing will not only filters your fuel but cleans the inside of the tank as well This will require decent pressure spraying back in the tank. I can't see how one would accomplish this unless designed from building of the tank So I guess one would have to settle for a good fuel filtering system I have two tanks ,so when my tanks are low, I pump all the fuel to one tank then back to the other tank. That way I hope I have cleaned all the fuel Has worked well so far Now, I am going to try and reattach my bow pulpit
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