Cleaning Diesel

[pmyatt]

Within the Mobo fraternity in the US, to prevent fuel storage contamination, many boats are fitted with a "Fuel Polishing System", basically a feed off the fuel tank, pumped through a filter/ filters and back into the tank. It is a subject not often discussed in the UK yachting media although, with regular talk off tank cleaning, fuel bug, winter lay-up etc., it is one that one would have thought would have been considered in detail. Am considering T-ing into fuel feed and, using a purpose designed 12 volt fuel transfer pump, passing the fuel through a 1 micron filter and then back into the tank via the fuel return pipe. It seems so simple I wonder why it has not been raised before - so what are the problems? Obviously there would be all the normal considerations of ensuring no air in the fuel feed to the engine, careful fusing of the power supply and making sure the pump was rated properly for continuous use etc., but surely it is not that easy?

 

[npf1]

I suspect a 1 Micron filter won't last very long before needing replacement.

 

[sarabande]

If it's downstream of the main filter ? I can see it clogging up at first, but when the fuel has been polished, it should last OK.

 

[Deleted member 36384]

I have noticed that many drilling rig owners use centrifuges to clean their diesel before using it on their engines. These centrifuges are very large but I wonder if there is a small unit that would suit your purpose. They could be quite expensive.

I also do a lot of filtering on various well fluids (including diesel). I would imagine that you will go through a lot of filters initially as your tank will be dirty. Once this residue is filtered out then your filter usage will go down. Of course if you make sure that the tank is clean first then you wont suffer the initial high attrition rate.

Looking for small centrifuges on the web I came across this item which looks interesting http://liquideng-europe.com/FuelPurifier.aspx

All the best.

 

[Bobobolinsky]

If you are making up a filter system , use a racor filter 30micron as a first stage and a 5 micron engine filter as a secondstage. For polishing fuel, I have used toilet rolls in the past as a filter medium. Just remove the cardboard and replace with a perforated metal tube screen. With a piece of tube with an oulet Squeeze down with a couple of bolts on a top plate and it's cheap filter medium. Drain em and they make good firelighters afterwards. Commercial diesel is formulated to cause no harm to an engine and is 5 micron filtered at the point of dispatch. So why are people looking at 1 micron filters. <5 micron particles will cause no harm to your pump or nozzles.
The other thing, is find the tank drain and fit a valve and tube from there. Gets all the water out the tank then as well. A custom pump sounds expensive, just use a 12v oil sump pump.
Robin

 

[NormanS]

Fuel tank design

A properly designed fuel tank has an integrated sump, into which all matter denser than the diesel fuel, including water, finds its way by gravity. Regular running off into a suitable container, saves most contamination ever getting to the filters. It is thin thin layer of water, present in tanks without sumps, which leads to the formation of The Bug.

 

[Bobobolinsky]

Having been on a delivery recently where at the first sign of swell both engines stopped, in the harbour mouth with not a whisper of breeze and a current carrying us down onto the local stickyout bit, I'll drink to cleaning out tanks. A mate subsequently took 50 litres of water out of the diesel tank.
Moral of the story is don't leave tank low on diesel for a year!
And fit Racors, if we had not been able to drain the water off every ten minutes, we would not have made it back to the pontoon and dignity would have been dented having to call out the lifeboat for a tow back.

Robin

 

[pmyatt]

A properly designed fuel tank has an integrated sump, into which all matter denser than the diesel fuel, including water, finds its way by gravity. Regular running off into a suitable container, saves most contamination ever getting to the filters. It is thin thin layer of water, present in tanks without sumps, which leads to the formation of The Bug.

I agree about the siting of the tank - and it was properly situated on our last Freedom for draining from the bottom. Unfortunately, our present Freedom has the fuel tank sitting on the hull underneath the starboard aft cabin berth - no way to get at any of it without ripping the boat apart, apart from a small area on the top where all the pipework is situated.

 

[pmyatt]

If you are making up a filter system , use a racor filter 30micron as a first stage and a 5 micron engine filter as a secondstage. For polishing fuel, I have used toilet rolls in the past as a filter medium. Just remove the cardboard and replace with a perforated metal tube screen. With a piece of tube with an oulet Squeeze down with a couple of bolts on a top plate and it's cheap filter medium. Drain em and they make good firelighters afterwards. Commercial diesel is formulated to cause no harm to an engine and is 5 micron filtered at the point of dispatch. So why are people looking at 1 micron filters. <5 micron particles will cause no harm to your pump or nozzles.
The other thing, is find the tank drain and fit a valve and tube from there. Gets all the water out the tank then as well. A custom pump sounds expensive, just use a 12v oil sump pump.
Robin

Was not aware of the 5 micron threshold - was guided by a PBO article some time ago, by Colin Jones, where a 1 micron filter was under consideration. The pump I am considering is a Jabsco 23220-2012 12 volt Junior Gear Puppy Pump @ approx. £110. Unfortunately there is no tank drain - the tank sits on the hull.

 

[Piers]

One important point about installing a fuel polishing system is the need for the returned fuel to be pumped at such a pressure and/or rate and to be angled towards the base of the tank, such that it stirs up whatever might be lurking in the tank thereby feeding the 'nasties' to the filters.

Too many systems have been installed which simply circulate clean fuel above the rubbish, thereby only cleaning the already clean fuel.

The better systems use the centrifuge, but filters are OK provided you have many spares.

 

[Chris_Robb]

A properly designed fuel tank has an integrated sump, into which all matter denser than the diesel fuel, including water, finds its way by gravity. Regular running off into a suitable container, saves most contamination ever getting to the filters. It is thin thin layer of water, present in tanks without sumps, which leads to the formation of The Bug.

Water also is the cause of many mild steel tanks rusting through. So getting rid of the water is a must on every ground.

I pump out the bottom of the tank each year using a 15mm coper pipe inserted by way of the deck filler (above the tank) I stir up the bottom, and then suck out 2 or 4 gallons ( or much less if clean). Having done this for the last 3 years, and for 8 years on my previous boat, the fuel gradually ends up with no dirt or water what so ever, so a 1 litre bottle suffices.

In the event of taking on contaminated fuel, I hope that I would be able to use this rig to immediatley suck from the bottom of the tank - that is of course, if I realized in time that I had picked up rubbish before the engine stopped!

I think this "stitch in time" method is really worth the bother each year.

 

[ianabc]

day tank...

Using a day tank helps.

This fairly inexpensive solution could use a hand pump.

We have a Whale 10 pump as a transfer pump, pumping through a Racor filter from the main tank in the keel to the day tank which has its outlet to the engine through the top of the tank. Having the outlet at the bottom would work but is not considered proper. Nor is a drainable sump but that would be good for removing water.

Then dual Racors before the engine.

I notice that not all Whale pumps use diesel oil resistant material.

 

[Ruffles]

In the past I've used the oil sump pump with the pipe attached to a garden cane with cable ties. But then I have an inspection hatch on our old steel tank so I can fish around for bits. When I last did it I found bits of rust but no water. Needs doing again but not my favourite job to be honest.

 

[savageseadog]

Inexpensive and effective way of cleaning fuel: Boil it, or at least heat it to hand hot. Contaminants will sink to the bottom, waxes and the like will re-dissolve (emulsify?) Obviously take care to ensure it doesn't catch fire and do it outdoors.

I'll wait for the news stories of yachties burning their houses down

 

[Deleted member 36384]

....... Having the outlet at the bottom would work but is not considered proper. Nor is a drainable sump but that would be good for removing water......

Ianabc is the supply to the engine (from the day tank) by syphon to the HP Injection Pump or to the LP lift pump. I guess if the tank is higher than the engine then the extra head will actually assist the diesel lift pump.

On the main tanks is the draw from the top as well? I read about a boat that had converted a cockpit cave locker to a day tank with a perspex front.

I am interested in the day tank idea.

Regards BOB

 

[lw395]

A properly designed fuel tank has an integrated sump, into which all matter denser than the diesel fuel, including water, finds its way by gravity. Regular running off into a suitable container, saves most contamination ever getting to the filters. It is thin thin layer of water, present in tanks without sumps, which leads to the formation of The Bug.

My method is to 'hoover' the water and black gunge out of the tank with a pela oil extractor.
The crud will easily block a 3mm hose let alone a 5 micron filter, so I use a bigger bore tube on the pela. a 3ft rigid section can be steered into the corners of the tank. A valve helps too, then you can pump up the vacuum without having to steer the tube at the same time.

The ideal conditions for bug growth are a large shallow tank with a big area of water:diesel interface.

On my Impala 28 (which had a very small plastic tank), I retrofitted a sump by fitting a blanked off tank fitting into the bottom of the tank. this was more to do with stopping the engine from sucking air when heeled with a low fuel level, but did mean all the water went quickly to the CAV filter, keeping the tank clean.