Diesel bug

[jdc]

It's not like a bacterial infection in the human body. There is no downside to over-dosing, other than cost.

Richard

Well, the IATA publication "Guidance Material on Microbiological Contamination in Aircraft Fuel Tanks", 5th edition says in Section 2.3.1: Generally, biocides are not allowed in the fuel specifications because the existence of the possibility of overdosing a fuel if both a fuel supplier and, further downstream, an airline treats the same fuel. Furthermore, it is possible that some suppliers would rely on biocide treatment to solve ongoing microbiological problems rather than investigating to determine and eradicate the root cause. Continuous or regular use of biocides, particularly at sub-lethal doses, may aggravate a problem and/or result in resistant strains of micro-organisms.

True, they don't spell out why overdosing would be bad, but they do warn against it.

 

[lw395]

The other issue with diesel treatments is that they generally disperse any water in the fuel.
This makes it impossible to ever remove the water.
If you have half a tank of treated diesel and add water to it, what happens? At some point there is more water than the treatment can deal with.
Whereas untreated diesel will allow your CAV filter or whatever to remove the water, or you can remove the water from the bottom of the tank.

 

[RichardS]

Well, the IATA publication "Guidance Material on Microbiological Contamination in Aircraft Fuel Tanks", 5th edition says in Section 2.3.1: Generally, biocides are not allowed in the fuel specifications because the existence of the possibility of overdosing a fuel if both a fuel supplier and, further downstream, an airline treats the same fuel. Furthermore, it is possible that some suppliers would rely on biocide treatment to solve ongoing microbiological problems rather than investigating to determine and eradicate the root cause. Continuous or regular use of biocides, particularly at sub-lethal doses, may aggravate a problem and/or result in resistant strains of micro-organisms.

True, they don't spell out why overdosing would be bad, but they do warn against it.

The biocide will, inevitably, have a slightly different energy capacity to the underlying fuel so will affect the running of the engine. This effect would not be noticeable in a marine engine until the level of biocide was far beyond what could be caused by normal over-dosing. However, with aero engines, one would not want unforeseen concentrations of anything in the tanks, for obvious reasons. :ambivalence:

Richard

 

[dom]

Well, the IATA publication "Guidance Material on Microbiological Contamination in Aircraft Fuel Tanks", 5th edition says in Section 2.3.1: Generally, biocides are not allowed in the fuel specifications because the existence of the possibility of overdosing a fuel if both a fuel supplier and, further downstream, an airline treats the same fuel. Furthermore, it is possible that some suppliers would rely on biocide treatment to solve ongoing microbiological problems rather than investigating to determine and eradicate the root cause. Continuous or regular use of biocides, particularly at sub-lethal doses, may aggravate a problem and/or result in resistant strains of micro-organisms.

True, they don't spell out why overdosing would be bad, but they do warn against it.

The specification, fuel composition, usage pattern and supply chains of aviation and marine fuels are vastly different. Large oil co.s like Exxon (Esso) are major suppliers to both industries and in the UK's case Exxon's marine offering specifically includes a pre-treated fuel suitable for the marine environment.

It is fun to have debates like this, but at the end of the day most will go with the products and advice offered by the big oil co. labs. Many sailors unfortunately don't follow this advice and end up catching the bug, simply because they don't know what the advice is.

 

[jdc]

...but at the end of the day most will go with the products and advice offered by the big oil co. labs. Many sailors unfortunately don't follow this advice and end up catching the bug, simply because they don't know what the advice is.

I agree wholeheartedly that most sailors would like to go with the the advice offered by the big oil co labs. But unfortunately this advice is not readily found and in its absence, a lot of misinformation circulates. The manufacturers of the additives exploit this by claiming that their stuff is endorsed somehow by rail and air - which it isn't - and generally adding to obfuscation and FUD.

If we yachts obeyed advice from oil companies we'd also avoid copper pipes and brass fittings btw.

 

[dom]

I agree wholeheartedly that most sailors would like to go with the the advice offered by the big oil co labs. But unfortunately this advice is not readily found and in its absence, a lot of misinformation circulates. The manufacturers of the additives exploit this by claiming that their stuff is endorsed somehow by rail and air - which it isn't - and generally adding to obfuscation and FUD.

If we yachts obeyed advice from oil companies we'd also avoid copper pipes and brass fittings btw.

Are you not being too sweeping in your condemnation of the additive manufacturers?

Moreover, we probably shld avoid most of those metals where possible, with the exception of small quantities of brass which is less reactive. Copper, lead, tin, zinc alongside metals that contain them such as lead solders, bronze (copper and tin) and of course brass (copper and zinc) all have a tendency to oxidize diesel and create sediments and other deposits which increase the likelihood of diesel bug and the risk of filter blockage.

Stainless steel, aluminium, certain polyethylenes and polypropylene, etc. are all perfectly good alternatives.

Water is arguably the biggest hazard and one of the reasons why road diesel which includes FAME is largely unsuitable for boats. Where used, increased vigilance is required with regards to both water and sediment control, up to and including some sort of polishing system.

Many marinas regard this advice as overly fussy and yotties seem largely happy to just slosh whatever happens to be at the pump, into a system with whatever fittings came to hand, and then leave the diesel sitting in the tank for ages, often much longer than the recommended 12 month guidance. They then wonder why they catch the bug!

Diesel should be treated more like beer, it needs caring for . And this care often includes biocides, sometimes added by the oil co's themselves.

 

[thinwater]

The other issue with diesel treatments is that they generally disperse any water in the fuel.
This makes it impossible to ever remove the water.
If you have half a tank of treated diesel and add water to it, what happens? At some point there is more water than the treatment can deal with.
Whereas untreated diesel will allow your CAV filter or whatever to remove the water, or you can remove the water from the bottom of the tank.

Actually, very few disperse for than ppm water. I have also tested effects on filtration. Generally there are none.

Moreover, i tis mistake to paint "treatments" with a broad brush. They are very, very different. The main anti-bug treatment (what this thread is about), Biobor, has none of these effects and does not claim them.

---

As for overdoseing, carbamate types will precipitate out as white crystals if over dosed or mixed poorly. Borinanes don't seem to do anything negative unless overdosed at some crazy rate.

Yes, Agree water absorbing additives are a bad idea. The engine manufactures agree. They don't want you burning what is probably saltwater.

 

[lw395]

Most people who talk about treating diesel bug are talking about retail packaged 'treatments', not pure biocides.
The compatibility of different 'treatments' is something that concerns me sometimes, as you never know what's been added upstream.

 

[CAPTAIN FANTASTIC]

Captain F, what you got in your LR was unlikely to be bacteria, but most likely to be waxing which entrains debris in the filter(s)- hence the colour. Bacteria much prefer warm temps.

The idea of petrol being poisonous to diesel bug is, frankly, untenable. Petrol contains ethanol, which is a food for bacteria.

Bacteria can grow in diesel tanks which do not have water entering e.g through a leaking filler. Water is an aid to bug growth, not a pre-requisite.

Diesel waxing is literally the waxing of diesel at low temperatures; which I am familiar with. I am referring to the gungy black tar staff due to bacterial growth. The fact that the problem appeared when the temperature was low could have been related to the change in viscosity affecting the tar; perhaps the gungy tar was formed when the temperature was higher.

 

[jdc]

... I am referring to the gungy black tar staff due to bacterial growth...

Gungy black tar can equally well be tar! By no means all, and probably the minority of, such deposits are due to microbial growth. Asphaltene is a decomposition product of diesel, and it has become much more common than hitherto since the introduction of ULSD. See for instance: http://fuelschool.blogspot.com/2009/02/asphaltenes-and-plugged-fuel-filters.html

Although this is a non-scientific and non peer-reviewed piece, much of what the author claims can be substantiated. The US military publish quite good guides on ULSD storage and decomposition. It also agrees exactly with my observations. I have some black tarry gunge in my tank, so I extracted some and mixed it with clean fuel to which I'd added 25% water and shook it all up. I then left it in a warm-ish place for a year. Absolutely zero evidence of any growth, so my black gunge at least was probably not microbial in origin.