Shelf Life of Diesel Fuel

[idpnd]

Interesting topic, especially as I have just purchased a ton of fuel which must have been sitting there a couple of years.. Will probably put biocide in, then attempt to filter. I have also heard of people vacuuming the bottom of the tank to get rid of condensated water/dirt? Could there be rust issues down there if you have steel tanks?

[Highlander40]

Sorry here it is. Parker Fuel Polishing Module - Prevent Fuel System Corrosion

This is new technology. It uses piezo actuators to move a diaphram and pumps about 50 gal / day.

[s/v Jedi]

Originally Posted by Tellie

I aways thought that would sure solve a lot of issues as well. I don't remember where or by whom, but I was once told that there is some regulation against having a sump drain or line at the bottom of a marine fuel tank. I suppose it has to do with fuel spillage if that point fails. Perhaps better minds here will know.

Tellie,

A sump is fine but US regulations forbid a tap under the sump. Dashew put a 1" plug in our sumps with the explanation of why he couldn't put the tap in there himself... and how to change that ;-)
Another (US legal) option is a pipe from the top into the sump to draw it out but you need a pump in that case.

cheers,
Nick.

[Solitude]

Thanks for the links Gord

I read through the BP one and pulled this out...

Fungicides/Biocides

. These work by stopping fungus and bacteria from growing in the fuel and so prolong the life of the fuel. They are only effective on fungus and bacteria and will not stop other oxidation reactions from taking place. They are normally active at the water fuel interface where the fungus and bacteria grow. If fungus is present then a kill dose is required. Otherwise a maintenance dose is used to stop fungus growing. The disadvantages of biocides are:

• handling and mixing is hazardous because they are poisons.

• for a kill dose, killing the fungus can lead to a build up of dead matter which will block filters and also cause the fuel to oxidise.

• ideally, the fungus should be killed and then the tank emptied and drained out.

• maintenance doses are effective but no more so than regular water draining.

• disposal of water bottoms requires special handling with due regard to the environment.

[Therapy]

Originally Posted by s/v Jedi

Exactly and that why we have that sump (every good tank should have one) and we have a drain under it instead of s pipe from the top down into the sump. This is where all the water ends up.

About asphaltenes: instead of diesel add-on products, you can circulate it on a regular basis (part of polishing) which takes care of it.

The only additive we use is the enzyme based bacteria control (Startron). We keep diesel for up to three years without any trouble.

cheers,
Nick.

Well thank goodness someone has one.

I mean really. It just seem so simple.

And I don't think it matters if you have a drain (safe one of course) or use a pump. I have a pump for my oil and tranny fluid. Will it work for diesel - probably.

Now I will wait till I have to replace my tanks (100 or so years) to get one made with a sump area.

All these years with all the same problems and no one - WAIT - one has a easy solution.

Egads! Sailors sure are a "slow to change" bunch.

Maybe I don't want to be one again really??

[DRS]

As a truck driver in Canada I never added gas to diesel. We would on occasion add small amouts of Methyl Hydrate (1 gal MH to 200 Gal diesel)to thefuel tanks as it would disperse any water and prevent jelling.

[Highlander40]

The best way to deal with fuel is totally avoid all the disasters, tank cleaning and gunk buildup.
The FPM module that I posted does a real interesting thing. By moving fuel through the Racor at a slow speed (2 gal/hr) the filter is able to get the smallest droplets of water as they form. Not as water entering the tank but as water Leaving Solution with diesel. The key thing here, is that a change (drop) in temperature is required to form droplets of water. This happens every day as things cool down in the evening. The amount of water that fuel will carry in solution is so small that only by pumping super slow will the racors catch it, as it becomes a discrete water droplet.
By running the polisher every day or even round the clock, the tank will never have water in it.
This method also eliminates the need for a sump or pickup tube that sits on the bottom, because the fuel itself is the carrier that brings water to the Racor for collection.
No algae, no biocide needed. The constant movement may help with asphaltene buildup too but for long term storage an addative that will be burned as fuel (unlike biocides) is a good idea.

I know that I am sounding like a salesman here but I am just looking to have the best system for my boat. The FPM does something that no other system will. It keeps the fuel dry wether you run the engines or not!

Carl

[s/v Jedi]

Carl,

Explain to me why the FPM is better than a sump that is used to drain water and gunk regularly?

cheers,
Nick.

[Highlander40]

Nick,
Water tends to settle in the same places in the tank. Even with regular draining (weekly?) there will be some corrosion over time. With less than perfect maint, some scum may grow.
With the FPM I would think that the life of the tank would be determined by external problems like vibration, corrosion, wear, mostly due to poor installation. (no worries for you).
Think about this- the entire amount of water in your tank at any time would be equal to the smallest droplet that water can form. OR the total amount in the Racor bowl.

Carl

[s/v Jedi]

Carl,

Okay, I follow you now. We have aluminium tanks so there is no corrosion and all the water settles in the sump, where I can easily drain it plus any scum (I only get some very dark fuel in the sump plus a little water).

Water getting in the fuel tank is a continuous process. It gets absorbed from the moisture in the air and, if the tank isn't topped off, from condensation on the inside walls. The FPM will keep filtering while I let it collect and settle in the sump and drain it regularly.

What worries me is the FPM running that many hours in combination with the stiff price. I am not so sure it will be trouble-free. Also, you still have the same draining process that I have (from the filter bowl). I guess we'll have to wait for reliability reports from users that have it a year or so.

cheers,
Nick.

[Highlander40]

Nick,
Over the past 10 years I found that any water or any biocide that was added, ended up in the racor, a day later. My fuel tank has a sump and that combined with a flow rate of about one gallon per minute, vacuums up everything. I am curious about the FPM though.
The pump uses a piezo driven diaphram, they wont say more than that.
The current draw is almost nothing and even if it did fail there are no shaft seals to leak.

The dark stuff you drain from the sump? does it smell just like biocide?

Carl

[s/v Jedi]

I use Startron (the blue stuff) and that mixes up with the diesel completely. It also turns the diesel into a much lighter color after a couple of days.

The dark stuff are the heavier components in diesel that isn't top quality (it separates). This is like it is everywhere in the Caribbean. I mix it back in with polishing but some doesn't pass the 10 micron filter I use for polishing. I draw fuel from the sump while polishing.

FPM: I don't worry about it's power draw nor leaks... I worry about having to replace it every year or so which would make it too expensive.

ciao!
Nick.

[Bada Vaniki]

In our part of the world (inland Australia) diesel fuel is delivered to farms as winter mix or summer mix. The winter mix has added heating oil to stop waxing but if kept into the hot summer months will start to grow nasties and cause problems. To complicate matters further if one visits the snowfields in the winter months they sell "Alpine mix" which contains anti-freeze. Safest bet is to use fuel within 6 months of purchase and always (where practicable) keep fuel tanks full to stop condensation.

[Laidback]

There are parts of the world where the Shelf Life of Diesel is less than a day. South East Asia is one of them - For cruisers buying diesel in Indonesian waters from fuel barges - 44 gall drums - jerry cans, you name it. A very good chance that it is already contaminated by water, by oxidized metal from tanks and drums and of course bacterial growth and other sediments. The answer is to filter the fuel BEFORE you pour it into your boat's tank.

The following companies all produce fast flow filter funnels which will take out all of the above contaminants:-
Shurhold
Mr. Funnel
Racor
Selco

Choose a model that will filter 3>>4 gallons per minute. Then once filtration is completed add a diesel biocide.

[sneuman]

Originally Posted by s/v Jedi

You can polish it yourself. Disconnect fuel feed hose from engine and connect it to a small pump (like those cheap impeller pumps you put in your electric drill). First, pump a gallon into a bucket and then switch to an empty tank, jerry jugs or even back into the same tank (deck fill). When the flow stops, replace the filter cartridge in the primary filter with a new one and toss the clogged one in the bucket. When it clogs again, flop the filter element in the bucket around a bit and put it to use again, alternating between the two elements as you go.

When you pump back into the same tank, you have to circulate 5 times the amount of fuel that's in the tank, so time how long it takes to pump that first gallon.

You can get unlucky when the pick-up tube in the tank is clogged. You have to remove the tube to clean it and I would advice to remove any mesh strainer it has (let the primary filter deal with filtering).

We have a fixed (self designed and installed) installation for that, plus the ability to drain from the bottom of the tanks. I first drain a little in a glass jar to check for water (and drain it all when I find it) before filtering. The fixed setup uses a seperate Racor 500 filter for this, plus a little Walbro pump. See s/v Jedi: A new fuel system for Jedi (English) for a complete description, photo's etc. When you build this yourself the cost is the Racor filter and the pump(s) (I use two pumps, one for bleeding/priming/boosting).

cheers,
Nick.

I just took a diesel class and learned that anything finer than a 30 micron filter is putting undue strain on the lift pump (which could puncture the diaphram and pour diesel into the crankcase). Does the "boost pump" solve that problem?