DIESEL, BIO-DIESEL AND DIESEL BUG
HISTORY
Sulphur in Diesel
Prior to 2001, there was 500 ppm of sulphur in road diesel - 1000 ppm in red diesel until 2011
From 2001 reduced to 350 ppm
From 2006 a maximum of 50 ppm of sulphur in diesel fuel
From 2008, ultra low sulphur diesel (ULSD) with a maximum of 10 ppm must be available
The Benefits of Sulphur in Diesel
Acted as a lubricant
Biocide killing off any bacteria, viruses, fungi and yeasts.
Biodiesel
In 2011, the sulphur in red diesel was reduced to 10 ppm in line with road diesel.
Some mineral diesel would still be available. It would appear that the railways take the bulk of this diesel, but certain marinas say that they supply FAME free diesel - this cannot be guaranteed. From 2011, all diesel supplied had to contain up to 7% fatty acid methyl esters (FAME) but it would appear that in reality this is anything from 5 - 10%. Where there have been problems, analysis of the fuel has found up to 18% FAME. This has irreversibly damaged high pressure fuel pumps and has overall been a very costly exercise.
There are many different types of biofuel - usually mixed - animal fat, fish oil, palm oil and rapeseed oil. some has a higher energy content - palm oil and this raises the temperature by 4 or 5 degrees (bad) and others have a low energy content like fish oil which causes idling and cold start problems.From 2012, the biodiesel is supposed to have risen to 12%, but this seems to have been delayed until at least 2015. Although the inclusion of Fame can resolve lubricity issues of ultra low sulphur diesel, it also promotes fuel oxidation and fuel instability. The ‘shelf life’ of Fame is between 6 and 12 weeks. An antioxidant is added to the biodiesel at the refinery but it ‘burns through’ within 12 weeks and it is only with the addition of the mineral diesel that it then has a ‘shelf life’ of between 3 and 6 months. This obviously creates problems when the fuel is or has been stored for longer than this either in storage tanks or in the boat tank. Oxidation of the fuel results in lower cetane levels which shows itself as loss of performance. It is incompatible with engine seals and sealants. The biggest problem, however, is its absorption of water and the formation of emulsions that has led to a series of potential issues for diesel users to occur in standing / stored diesel in the UK.
HISTORY
Sulphur in Diesel
Prior to 2001, there was 500 ppm of sulphur in road diesel - 1000 ppm in red diesel until 2011
From 2001 reduced to 350 ppm
From 2006 a maximum of 50 ppm of sulphur in diesel fuel
From 2008, ultra low sulphur diesel (ULSD) with a maximum of 10 ppm must be available
The Benefits of Sulphur in Diesel
Acted as a lubricant
Biocide killing off any bacteria, viruses, fungi and yeasts.
Biodiesel
In 2011, the sulphur in red diesel was reduced to 10 ppm in line with road diesel.
Some mineral diesel would still be available. It would appear that the railways take the bulk of this diesel, but certain marinas say that they supply FAME free diesel - this cannot be guaranteed. From 2011, all diesel supplied had to contain up to 7% fatty acid methyl esters (FAME) but it would appear that in reality this is anything from 5 - 10%. Where there have been problems, analysis of the fuel has found up to 18% FAME. This has irreversibly damaged high pressure fuel pumps and has overall been a very costly exercise.
There are many different types of biofuel - usually mixed - animal fat, fish oil, palm oil and rapeseed oil. some has a higher energy content - palm oil and this raises the temperature by 4 or 5 degrees (bad) and others have a low energy content like fish oil which causes idling and cold start problems.From 2012, the biodiesel is supposed to have risen to 12%, but this seems to have been delayed until at least 2015. Although the inclusion of Fame can resolve lubricity issues of ultra low sulphur diesel, it also promotes fuel oxidation and fuel instability. The ‘shelf life’ of Fame is between 6 and 12 weeks. An antioxidant is added to the biodiesel at the refinery but it ‘burns through’ within 12 weeks and it is only with the addition of the mineral diesel that it then has a ‘shelf life’ of between 3 and 6 months. This obviously creates problems when the fuel is or has been stored for longer than this either in storage tanks or in the boat tank. Oxidation of the fuel results in lower cetane levels which shows itself as loss of performance. It is incompatible with engine seals and sealants. The biggest problem, however, is its absorption of water and the formation of emulsions that has led to a series of potential issues for diesel users to occur in standing / stored diesel in the UK.
Diesel Bug
The collective term for bacteria, viruses, fungi and yeasts that feed at the water / diesel interface in the tank. Elevated temperatures during summer and autumn provide the ideal conditions for Diesel Bug to rapidly grow. In the right conditions, a single bacterium can multiply to billions in a very short time. It was seen before the loss of sulphur in diesel, but to a much lesser extent.
Where there is water present in the diesel, it appears cloudy and there will be water beneath the diesel. It is at this diesel/water interface that the diesel bug grows. It is usually browny black in colour and slimy. If, however it is gritty, then it may well be corrosion from the tank or varnish from the degradation of the diesel.
Boat owners need to be aware as they are regularly cruising during this summer/autumn period that this churns the fuel, dispersing the bug throughout the system, fully contaminating the fuel stock. However, the same applies to any diesel equipment that stands with fuel in for long periods in the right conditions. Acid is produced as a waste product with significant consequences for metal parts including fuel tanks, fuel lines, engine components and fuel pumps as well as rubber pipes and seals.
Prevention of Diesel Bug
Use the boat / fuel regularly
Buy fuel from suppliers with a large turnover. Unfortunately, Diesel bug is now present in the supplier’s tanks. This means that the fuel you buy may well be already contaminated. It will have left the refinery with a biocide in the Fame component, but it would appear that some fuel is escaping the net and is contaminated. It is therefore very important to use the correct additives.
Fuel Additives
There are two types of biocides :-
Enzymes - these have a shelf life of about 6 months, and are killed off by chemicals. They break down in hot weather and in hot recirculated fuel. Their efficacy is reduced in cold weather and they absorb water causing emulsification.
Names of Enzyme Biocides :-
Fortron Total Enzyme, Soltron
Starbrite - StarTron Diesel additive.
All the ‘Trons’ are enzymes
Chemical - Have an indefinite shelf life. They do not break down. Chemical additives are much preferable to enzymes, which CANNOT BE RECOMMENDED.
Names of Chemical Biocides
Exocet - Marine Fuel Conditioner - contains Cetane boosters improving the combustion efficiency - improving power (Cetane Number - 51), increasing shelf life, increasing lubricity, increasing the fuel’s resistance to microbial contamination, increasing the fuel’s resistance to water pick-up and it contains contains a combustion catalyst.
Exocet Anti-Bug Kill - Kills Bacteria, viruses, fungi and yeasts within 24-36 hours. Eliminates clogging of filters etc., protects against pipe and tank corrosion and has no adverse affects on steels, aluminium and zinc, nor polyethylene and polypropylene. This is used for contaminated fuel.
Exocet Fuel Store Plus - Contains a high dose of antioxidant. Delays formation of gums and solids. It maintains the fuels ignition qualities and extends the shelf life to approximately 2 years. It contains a fuel soluble biocide at a maintenance dose reducing the potential for microbial growth. It has corrosion inhibition properties and reduces the potential for filter clogging.
Grotamar 82 is similar to Exocet Marine Fuel Conditioner, whilst Grotamar 71 is used for contaminated fuel.
Marine 16 - Diesel Fuel Complete is similar to Exocet Marine Fuel Conditioner, whilst Diesel Bug Treatment is used for contaminated fuel.
One Shot Diesel Additives are very similar to the Fast Exocet products
Racor biocide - expensive and not easy to obtain - undoubtedly it will be good.
The collective term for bacteria, viruses, fungi and yeasts that feed at the water / diesel interface in the tank. Elevated temperatures during summer and autumn provide the ideal conditions for Diesel Bug to rapidly grow. In the right conditions, a single bacterium can multiply to billions in a very short time. It was seen before the loss of sulphur in diesel, but to a much lesser extent.
Where there is water present in the diesel, it appears cloudy and there will be water beneath the diesel. It is at this diesel/water interface that the diesel bug grows. It is usually browny black in colour and slimy. If, however it is gritty, then it may well be corrosion from the tank or varnish from the degradation of the diesel.
Boat owners need to be aware as they are regularly cruising during this summer/autumn period that this churns the fuel, dispersing the bug throughout the system, fully contaminating the fuel stock. However, the same applies to any diesel equipment that stands with fuel in for long periods in the right conditions. Acid is produced as a waste product with significant consequences for metal parts including fuel tanks, fuel lines, engine components and fuel pumps as well as rubber pipes and seals.
Prevention of Diesel Bug
Use the boat / fuel regularly
Buy fuel from suppliers with a large turnover. Unfortunately, Diesel bug is now present in the supplier’s tanks. This means that the fuel you buy may well be already contaminated. It will have left the refinery with a biocide in the Fame component, but it would appear that some fuel is escaping the net and is contaminated. It is therefore very important to use the correct additives.
Fuel Additives
There are two types of biocides :-
Enzymes - these have a shelf life of about 6 months, and are killed off by chemicals. They break down in hot weather and in hot recirculated fuel. Their efficacy is reduced in cold weather and they absorb water causing emulsification.
Names of Enzyme Biocides :-
Fortron Total Enzyme, Soltron
Starbrite - StarTron Diesel additive.
All the ‘Trons’ are enzymes
Chemical - Have an indefinite shelf life. They do not break down. Chemical additives are much preferable to enzymes, which CANNOT BE RECOMMENDED.
Names of Chemical Biocides
Exocet - Marine Fuel Conditioner - contains Cetane boosters improving the combustion efficiency - improving power (Cetane Number - 51), increasing shelf life, increasing lubricity, increasing the fuel’s resistance to microbial contamination, increasing the fuel’s resistance to water pick-up and it contains contains a combustion catalyst.
Exocet Anti-Bug Kill - Kills Bacteria, viruses, fungi and yeasts within 24-36 hours. Eliminates clogging of filters etc., protects against pipe and tank corrosion and has no adverse affects on steels, aluminium and zinc, nor polyethylene and polypropylene. This is used for contaminated fuel.
Exocet Fuel Store Plus - Contains a high dose of antioxidant. Delays formation of gums and solids. It maintains the fuels ignition qualities and extends the shelf life to approximately 2 years. It contains a fuel soluble biocide at a maintenance dose reducing the potential for microbial growth. It has corrosion inhibition properties and reduces the potential for filter clogging.
Grotamar 82 is similar to Exocet Marine Fuel Conditioner, whilst Grotamar 71 is used for contaminated fuel.
Marine 16 - Diesel Fuel Complete is similar to Exocet Marine Fuel Conditioner, whilst Diesel Bug Treatment is used for contaminated fuel.
One Shot Diesel Additives are very similar to the Fast Exocet products
Racor biocide - expensive and not easy to obtain - undoubtedly it will be good.
Fuel Set - This is neither an enzyme nor a biocide. It is a blend of solvents used in paint and contains Methanol which is extremely toxic. It does not kill bugs.
FILTERS
We now need to look at the fuel and how to clean and keep it clean by removing impurities such as water, debris and the diesel bug, which will be dead - it has a short half life of about 24 hours. Thus the need for in-line filtration. All our boats have primary and secondary filters, but it is now almost essential to consider putting a pre-filter in line before the primary filter itself. There are two different types of pre-filter that are in common use :-
MLS Purifier - The Vortex filter (filterless filter). This works by spinning the fuel and dropping the water and debris into the bowl. This is drained off. There is no actual filter, therefore there is no maintenance. Disadvantages are that the larger filters do not work as well and debris will pass through them as the fuel does not spin so proficiently. Neither is there any visible means of seeing any water or debris. A water sensor can be added which will sound an alarm when water reaches that level This filter used to be known as an agglomerator.
Fuel Guard Decontaminator. Having a glass bowl, one can see what is going on. Water can be drained off and should the green conical filter contain debris, then it can easily be removed and cleaned. As the filter is 40 microns, it is too fine to act as a pre-filter but not fine enough to act as a filter.
FILTERS
We now need to look at the fuel and how to clean and keep it clean by removing impurities such as water, debris and the diesel bug, which will be dead - it has a short half life of about 24 hours. Thus the need for in-line filtration. All our boats have primary and secondary filters, but it is now almost essential to consider putting a pre-filter in line before the primary filter itself. There are two different types of pre-filter that are in common use :-
MLS Purifier - The Vortex filter (filterless filter). This works by spinning the fuel and dropping the water and debris into the bowl. This is drained off. There is no actual filter, therefore there is no maintenance. Disadvantages are that the larger filters do not work as well and debris will pass through them as the fuel does not spin so proficiently. Neither is there any visible means of seeing any water or debris. A water sensor can be added which will sound an alarm when water reaches that level This filter used to be known as an agglomerator.
Fuel Guard Decontaminator. Having a glass bowl, one can see what is going on. Water can be drained off and should the green conical filter contain debris, then it can easily be removed and cleaned. As the filter is 40 microns, it is too fine to act as a pre-filter but not fine enough to act as a filter.
DIESEL POLISHING SYSTEMS
Small Diesel Polishing Systems are available to be put in line within the fuel system and used when the boat is moored. They remove any water and debris, thus preventing the formation of the diesel bug and keep the fuel in good condition. They should be used in conjunction with the appropriate fuel additive. There are a number of these available - often from America - the American ones are very expensive.
Small Diesel Polishing Systems are available to be put in line within the fuel system and used when the boat is moored. They remove any water and debris, thus preventing the formation of the diesel bug and keep the fuel in good condition. They should be used in conjunction with the appropriate fuel additive. There are a number of these available - often from America - the American ones are very expensive.
USA - Algae X Fuel Polishing System
The Algae X Fuel polishing system uses a Marco pump to produce a medium pressure system with a pump life of approximately 5,000 hours. If this springs a leak, fuel may be sprayed into the engine bay. If fuel only goes into the tray, then the automatic shut-off valve operates when the fuel reaches a certain level within the tray. This system, working at medium pressure, is supposed to also clean the tank. The Algae-X uses a Parker disposable filter element. Although a very good system it is prohibitively expensive.
The Algae X Fuel polishing system uses a Marco pump to produce a medium pressure system with a pump life of approximately 5,000 hours. If this springs a leak, fuel may be sprayed into the engine bay. If fuel only goes into the tray, then the automatic shut-off valve operates when the fuel reaches a certain level within the tray. This system, working at medium pressure, is supposed to also clean the tank. The Algae-X uses a Parker disposable filter element. Although a very good system it is prohibitively expensive.
UK - PDF100 Fuel polishing system.
This uses either a Fuel Guard Decontaminator or a MLS Purifiner - this is the customers choice. It also uses a solid state Facet fuel pump which has a life of approximately 30,000 hours and is cheap to replace. Like the Algae X, water can be drained from the filter. As it is enclosed in a cabinet, should a leak occur, there is no external spill of fuel and the machine has a cut-off switch. The fuel flows into the sump which can be drained. The filter is cleanable. The PDF100 is a low pressure system and is designed to keep the fuel clean and water free. It is not designed to clean the tank, which should have already been cleaned if it was contaminated.
DIESEL BUG REMOVAL
Once the fuel is heavily contaminated, it becomes expensive, requiring the fuel filters to be replaced and often fuel polishing, which will also clean the tank. Diesel Bug also produces acid as a waste product and has significant consequences for all internal metal parts including fuel lines, engine components, fuel pumps and fuel tanks as well as rubber seals where used. If rubber seals and pipes require replacement, the material of choice is Viton - a fluoroelastomer manufactured by Du Pont. Nitrile may also be used.
It is said that it is possible to visualise the bottom of the tank using fibre optic equipment - this is rubbish. You know when there is a problem when the boat loses power and the filters are blocked. When changed they immediately block again. This is the point where the tank needs cleaning and the fuel polishing. Costs vary and are dependant on the access to the tank and the tank volume. Whilst the tank is being cleaned it is dosed with the appropriate biocide which will ensure that there is no reinfection.
In summary - Once the fuel and tank are clean - to maintain it that way :-
Use the appropriate fuel additive
Keep the tank topped up with fresh fuel from a supplier who has a large turnover of fuel.
Use the boat regularly.
When laying up the boat for the winter use a fuel storage additive.
Once the fuel is heavily contaminated, it becomes expensive, requiring the fuel filters to be replaced and often fuel polishing, which will also clean the tank. Diesel Bug also produces acid as a waste product and has significant consequences for all internal metal parts including fuel lines, engine components, fuel pumps and fuel tanks as well as rubber seals where used. If rubber seals and pipes require replacement, the material of choice is Viton - a fluoroelastomer manufactured by Du Pont. Nitrile may also be used.
It is said that it is possible to visualise the bottom of the tank using fibre optic equipment - this is rubbish. You know when there is a problem when the boat loses power and the filters are blocked. When changed they immediately block again. This is the point where the tank needs cleaning and the fuel polishing. Costs vary and are dependant on the access to the tank and the tank volume. Whilst the tank is being cleaned it is dosed with the appropriate biocide which will ensure that there is no reinfection.
In summary - Once the fuel and tank are clean - to maintain it that way :-
Use the appropriate fuel additive
Keep the tank topped up with fresh fuel from a supplier who has a large turnover of fuel.
Use the boat regularly.
When laying up the boat for the winter use a fuel storage additive.