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Fuel dyes are dyes added to fuels, as in some countries it is required by law to dye a low-tax fuel to deter its use in applications intended for higher-taxed ones. Untaxed fuels are referred to as "dyed", while taxed ones are called "clear" or "white".
Aviation gasoline is dyed, both for tax reasons (avgas is typically taxed to support aviation infrastructure) as well as safety (due to the consequences of fuelling an aircraft with the wrong kind of fuel).
Types of Dyes
The dyes used have to be soluble in the fuels they are added to and therefore in hydrocarbon-based nonpolar solvents ("solvent dyes"). Red dyes are often various diazo dyes, e.g., Solvent Red 19, Solvent Red 24, and Solvent Red 26. Anthraquinone dyes are used for green and blue shades, e.g., Solvent Green 33, Solvent Blue 35 and Solvent Blue 26.
The pure dyes found in modern liquid petroleum dyes are essentially longer alkyl side chain forms of traditional dyes and normally multiple chain length variations of the chromophore are found within a typical commercial liquid petroleum dye. For instance, Sudan Red 462 is essentially Solvent Red 19, with the ethyl side chain replaced by either a 2-ethylhexyl or a tridecyl side chain. The longer branched side chains improve solubility dramatically, but in some cases the high solubility prevents the dye being isolated as a crystal, except at very low temperatures. The high solubility liquid dyes originated with Morton International and BASF (ACNA Italy) as the primary inventors. For instance, Morton International created Solvent Blue 98 as a high solubility form of Solvent Blue 35. BASF created Solvent Blue 79 as its high solubility form of Solvent Blue 35. In some cases it is possible, with normal solvents—e.g., xylene—to prepare stable (to -20C) solutions at 65% "solids" content. The original powder dye form of the chromophore would not be soluble beyond 2% in xylene.
Only a few refineries worldwide still use powder dyes for colouring fuels, as ultimately they are still lower cost per active molecule of dye chromophore than the modified forms. They have significant handling issues and health and safety issues that inherently arise from the handling of azo dyes (reds/yellows/green mixes). It is advantageous to mix a liquid with a liquid instead of handling powdered dyes into a liquid.
Fuel dye in the European Union
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After August 2002, all European Union countries became obliged to add about 6 mg/L (0.034 oz/bbl) of Solvent Yellow 124, a dye with structure similar to Solvent Yellow 56, to heating fuel. This dye can be easily hydrolyzed with acids, splitting off the acetal group responsible for its solubility in nonpolar solvents, and yielding a water-soluble form. Like a similar methyl orange dye, it changes color to red in acidic pH. It can be easily detected in the fuel at levels as low as 0.3 ppm by extraction to a diluted hydrochloric acid, allowing detection of the red diesel added into motor diesel in amounts as low as 2–3%. The European Union has announced that has found a new and better marker to replace Solvent Yellow 124.[full citation needed]
In the United Kingdom, "red diesel" is dyed gas oil for registered agricultural or construction vehicles such as tractors, excavators, cranes and some other non-road applications such as boats. Red diesel carries a significantly reduced tax levy compared to un-dyed diesel fuel used in ordinary road vehicles. As red diesel is widely available in the UK, the authorities regularly carry out roadside checks. Unauthorised use incurs heavy fines but despite this, spot checks have occasionally found as many as one in five motorists using red diesel.
Red diesel can also be used in road vehicles which are registered as off-road with the DVLA provided they are only used on private land. On 14 July 2014, the European Commission announced it was referring the United Kingdom to the European Court of Justice over the use of red-diesel in propelling private pleasure craft on water. It believes the UK is not properly applying EU regulations for the fiscal marking of fuels.
On 18 November 2014, a new measure to combat fuel laundering should result in the illegal trade being "virtually eliminated" in the United Kingdom, according to HM Revenue and Customs. A new dye was introduced in April 2015 in the United Kingdom and the Republic of Ireland.
Carbon offset red diesel
Carbon offset red diesel is, as of 2014, available in the UK. It is marketed as an environmentally friendly alternative to regular red diesel. There is an extra cost incurred when purchasing carbon offset red diesel, however some[clarification needed] suppliers of the fuel are donating the extra cost to projects aimed at lowering carbon emissions, meaning they make no extra profit from the sale of the fuel.
Low-tax dyed fuel oil (Finnish: polttoöljy; Swedish: brännolja; always abbreviated on nozzles as MPÖ), is available in many rural petrol stations in Finland, primarily intended for certain types of non-road vehicles such as tractors and driveable construction vehicles. Until 2002, furfural was used to dye fuel oil in Finland, when it was replaced with Solvent Yellow 124. Since 2008, boats and pleasure craft are no longer legally allowed to use low-tax fuel oil, instead taxable diesel must be used for fuel.
Currently there are no naked-eye visible dyes in car fuels sold in Poland. However, during the time of Communist Party rule, the state-owned CPN fuel monopoly dyed leaded gasolines (marketed as "ethilins") in the following colors: 78 – blue, 86 – green, 94 – yellow, 98 – red. Diesel fuel, although unleaded, was also dyed a brown color.
Fuel dye in North America
In the United States of America, the Environmental Protection Agency mandates use of a red dye to identify fuels for off-road use. Solvent Red 26 is used in the United States as a standard, though it is often replaced with Solvent Red 164, which is similar to Solvent Red 26 but with longer alkyl chains. The Internal Revenue Service regulation 26 CFR 48.4082-1 mandates use of the same red dyes, in fivefold concentration, for tax-exempt diesel fuels such as heating oil; their argument for the higher dye content is to allow detection even when diluted with "legal" fuel. Detection of red-dyed fuel in the fuel system of an on-road vehicle will incur substantial penalties.
Organised crime gangs may "launder" low-price dyed fuel, removing the dye and selling it illegally to unsuspecting motorists at the higher price of undyed fuel. Paramilitary groups connected to political unrest in Northern Ireland have established laundering plants on both sides of the Irish border. In 2004, Northern Irish police discovered an illegal facility capable of removing the dye from 12 million L (2.6 million imp gal; 3.2 million US gal). In 2009, customs officials shut down a plant capable of removing the dye from 6.5 million litres of fuel per year. In 2011, a plant capable of processing 30 million litres was discovered.
Dyes Used By Country
Some dyes required in some countries are listed here:
|Australia||Regular unleaded petrol||undyed - clear to yellow (was purple or brown up to 2013, was red/orange until 2015)|
|Premium unleaded petrol||undyed - clear to yellow|
|Austria||Heating oil||any red dye and Solvent Yellow 124|
|Canada||Off-road fuel (agriculture, construction, mining etc.)||red/purple dye|
|Marine gasoline||any red dye|
|Heating oil||any red dye|
|Finland||Heating oil||Solvent Yellow 124|
|Diesel for construction and agriculture||Solvent Yellow 124|
|France||Diesel (heating/off-road)||Solvent Red 24 and Solvent Yellow 124|
|Marine diesel||Solvent Blue 35|
|Latvia||Heating oil||The used chemical substance is N-ethyl-N- [2- (1-iso butoxyethoxy) ethyl] azobenzene-4-amine (Solvent Yellow 124). SIA “Straujupīte” for diesel labeling is using no more than 0.2% of sulfur content.
Diesel is labeled by adding one of the coloring matters to 1000 liters of oil products::
|Agricultural diesel||fiscal marker - chemical N-ethyl-N- [2- (1-isobutoxyethoxy) ethyl] -4- (phenylazo) aniline (Solvent Yellow 124, CAS Nr.34432-92-3) - at least 6.0 grams, and no more than 9.0 grams; on 1000l|
|blue colorant 1,4-bis (butylamino) -9,10-anthraquinone (Sovlent Blue 35, CAS no. 17354-14-2) or any other equivalent blue coloring - at least 7.0 grams on 1000l|
|Estonia||Heating oil||Automate Red NR or similar|
|Agricultural diesel||Automate Blue 8 GHF or similar|
|Germany||Heating oil||Solvent Yellow 124 + 4.1 gr/litre Solvent Red 19 or 5.3 gr tolyazotolyazo-ethylhexylbetanaphthylamine or 6.1 gr tolyazotolyazo-tridecylbetanaphthylamine & similar|
|Greece||Heating oil||any red dye|
|Marine diesel||any black dye|
|Indonesia||Pertalite (RON 90)||Green dye|
|PERTAMAX (RON 92)||Blue dye|
|PERTAMAX Turbo (RON 98)||Red dye|
|Ireland||Gas oil||green dye = Solvent Yellow 124 and Anthraquinone Blue dye equivalent to Solvent Blue 35 and ACCUTRACE S10 ((3-(sec-butyl)-4-(decyloxy)phenyl)methanetriyl)tribenzene]]|
|Kerosene||Solvent Red 19, Solvent Yellow 124 and ACCUTRACE S10 ((3-(sec-butyl)-4-(decyloxy)phenyl)methanetriyl)tribenzene|
|Italy||Heating oil||Solvent Red 161|
|Gas oil||Solvent Green 32 or 33 and Solvent Yellow 124|
|Netherlands||Agricultural diesel||any red dye and Solvent Yellow 124 (the additive Furfural is obsolete)|
|Norway||Agricultural diesel||any green dye|
|Portugal||Agricultural diesel||Solvent Blue 35|
|Heating oil||Solvent Red 19 and similar|
|Spain||Agricultural diesel||any red dye + Solvent Yellow 124: Orden PRE/1724/2002 of the 5th of July.|
|Heating oil||any blue dye + Solvent Yellow 124: Orden PRE/1724/2002 of the 5th of July.|
|Sweden||Heating oil||Solvent Blue 35, Solvent Blue 79, Solvent Blue 98 and Solvent Yellow 124|
|Thailand||Gasoline 95||yellow dye|
|Gasoline 91||red dye|
|United Kingdom||Gas oil ("red diesel")||Solvent Red 24, quinizarin, Solvent Yellow 124 and ((3-(sec-butyl)-4-(decyloxy)phenyl)methanetriyl)tribenzene|
|Rebated kerosene||Coumarin, Solvent Yellow 124 and ((3-(sec-butyl)-4-(decyloxy)phenyl)methanetriyl)tribenzene|
|Europe||many rebated||Solvent Yellow 124 ("Euromarker")|
|United States||low-tax fuels, high-sulfur fuels||Solvent Red 26 3.9 lbs per 1000 barrels (11 mg/L), Solvent Red 164|
|Worldwide||Aviation gasoline 80/87||red dye|
|Aviation gasoline 82UL||purple dye|
|Aviation gasoline 100LL||blue dye|
|Aviation gasoline 100/130||green dye|
- "New and better Euromarker for labelling of gas oil and kerosene". 17 July 2017.
- "Evaluation of the performance of the short-listed candidate markers regarding the technical requirements: Call for expression of interest to present products suitable for use as a marker in gas oils and kerosene". 6 July 2017.
- "Thousands using illegal car fuel". BBC News. 3 November 2007. Retrieved 16 April 2008.
- "EC to take UK to court over red diesel". RYA. 14 July 2014. Retrieved 1 August 2014.
- "HMRC: New diesel dye 'should eliminate fuel laundering'". BBC News. 18 November 2014.
- "Carbon Offset Red Diesel". Crown Oil Ltd. 2014.
- "Blackmarket Britain: Fake Fuel". BBC News. 9 June 2004. Retrieved 16 April 2008.
- "Illegal fuel plant largest in NI". BBC News. 1 December 2009. Retrieved 1 December 2009.
- "UK's biggest fuel laundering plant found in Crossmaglen". BBC News. 16 March 2011. Retrieved 17 March 2011.
- "Bord na Móna to dye fuel to fight theft". Irish Times. 11 December 2012. Retrieved 6 June 2015.
- "The colour of Australian unleaded petrol is changing to red/orange" (PDF) (Press release). Australian Institute of Petroleum. 28 September 2012. Archived from the original (PDF) on 9 April 2013. Retrieved 22 November 2012.
- "THE COLOUR OF AUSTRALIAN UNLEADED PETROL IS CHANGING" (PDF). Australian Institute of Petroleum. Retrieved 28 March 2020.
- "Par akcīzes nodokli". LIKUMI.LV (in Latvian). Retrieved 2 April 2017.
- Gorringe, Jason (22 December 2014). "Ireland To Use New Marker For Lower Duty Fuels". Tax-News.com.
- "Revenue and Customs Brief 4 (2015): introduction of a new rebated fuel marker from 1 April 2015". gov.uk.
- Minnesota State Patrol Commercial Vehicle Enforcement Dyed Fuel Program
- Shell information on aviation gasoline specifications
- Crown Oil fuel dye information