DIESEL FUEL DYEING IN THE U.S.
In the U.S., a confusing situation for both refiners and purchasers of diesel fuel has arisen
because the IRS and the EPA require the addition of red dye to certain classes of diesel
fuel. Each agency requires adding the dye to a different class of fuel, at a different concentration,
and for a different reason such as:
The EPA wants to identify diesel fuel with high-sulfur content to ensure that it is not
used in on-road vehicles.
The IRS wants to ensure that tax-exempt high-sulfur and low-sulfur diesel fuel are not
used for taxable purposes.
The EPA Requirements
U.S. EPA regulations require "visible evidence of the presence of red dye" to identify high sulfur
fuels when they leave the refinery. In practice, this requires refiners to add a level
of red dye that is equivalent to no more than 0.75 pounds/1,000 bbl (ptb) (2.14 mg/L)
of a solid Solvent Red 26 dye standard. Solvent Red 26 was chosen as the standard
because it is a unique chemical available in pure form. Diesel fuels are actually dyed with
liquid concentrates of Solvent Red 164 because this dye is more fuel soluble and less
costly than the standard. Solvent Red 164 is a mixture of isomers that are very similar to
Solvent Red 26, except the former incorporates hydrocarbon (alkyl) chains to increase its
solubility in petroleum products.
Any red dye observed in the fuel of a vehicle in on-road use triggers a measurement of the
fuels sulfur content. Penalties are assessed based on the actual sulfur content of the fuel,
rather than simply on the presence of dye.
As of June 2012, only heating oil will require red dye for EPA purposes. By then,
on-road, non-road, locomotive, and marine diesels will all be ULSD.
The Internal Revenue Service (IRS) Requirements
U.S. IRS regulations require that tax-exempt diesel fuels, both high-sulfur and low-sulfur,
have a minimum level of a Solvent Red 164 dye that is spectrally equivalent to 3.9 ptb
of the Solvent Red 26 dye standard. This level of dye is more than five times the amount
required by the EPA regulations. The IRS contends that the high dye level is necessary to
allow detection of tax evasion even after five-fold dilution of dyed fuel with undyed fuel.
In the U.S., a confusing situation for both refiners and purchasers of diesel fuel has arisen
because the IRS and the EPA require the addition of red dye to certain classes of diesel
fuel. Each agency requires adding the dye to a different class of fuel, at a different concentration,
and for a different reason such as:
The EPA wants to identify diesel fuel with high-sulfur content to ensure that it is not
used in on-road vehicles.
The IRS wants to ensure that tax-exempt high-sulfur and low-sulfur diesel fuel are not
used for taxable purposes.
The EPA Requirements
U.S. EPA regulations require "visible evidence of the presence of red dye" to identify high sulfur
fuels when they leave the refinery. In practice, this requires refiners to add a level
of red dye that is equivalent to no more than 0.75 pounds/1,000 bbl (ptb) (2.14 mg/L)
of a solid Solvent Red 26 dye standard. Solvent Red 26 was chosen as the standard
because it is a unique chemical available in pure form. Diesel fuels are actually dyed with
liquid concentrates of Solvent Red 164 because this dye is more fuel soluble and less
costly than the standard. Solvent Red 164 is a mixture of isomers that are very similar to
Solvent Red 26, except the former incorporates hydrocarbon (alkyl) chains to increase its
solubility in petroleum products.
Any red dye observed in the fuel of a vehicle in on-road use triggers a measurement of the
fuels sulfur content. Penalties are assessed based on the actual sulfur content of the fuel,
rather than simply on the presence of dye.
As of June 2012, only heating oil will require red dye for EPA purposes. By then,
on-road, non-road, locomotive, and marine diesels will all be ULSD.
The Internal Revenue Service (IRS) Requirements
U.S. IRS regulations require that tax-exempt diesel fuels, both high-sulfur and low-sulfur,
have a minimum level of a Solvent Red 164 dye that is spectrally equivalent to 3.9 ptb
of the Solvent Red 26 dye standard. This level of dye is more than five times the amount
required by the EPA regulations. The IRS contends that the high dye level is necessary to
allow detection of tax evasion even after five-fold dilution of dyed fuel with undyed fuel.
