5.1 In the United States, high sulfur content distillate products and diesel fuel used for off-road purposes, other than aviation turbine fuel, are required to contain red dye. A similar dye requirement exists for tax-free distillates. Contamination of aviation turbine fuel by small quantities of red dye has occurred. Such contamination presents major problems because airframe and engine manufacturers have severely limited operation on aviation turbine fuel containing red dye.

5.2 An alternate methodology for the determination of the presence of red dye in aviation turbine fuel is the observation of the color of the fuel when placed in a white bucket. The presence of the dye can be masked in aviation turbine fuels having dark Saybolt color. This test method provides an objective means of quickly measuring red dye concentration, but to avoid confusion with trace levels of other materials which will be indicated by the instrument, the method requires that instrument readings below 0.026 mg/L be reported as No Dye Present.

5.3 The color of the base fuel is masked by the presence of the red dye. This test method provides a means of estimating the base color of aviation turbine fuel and kerosine in the presence of red dye.

1.1 This test method covers the determination of the red dye concentration of aviation turbine fuel and kerosine and the estimation of the Saybolt color of undyed and red dyed (<0.750 mg/L of Solvent Red 26 equivalent) aviation turbine fuel and kerosine. The test method is appropriate for use with aviation turbine fuel and kerosine described in Specifications D1655 and D3699. Red dye concentrations are determined at levels equivalent to 0.026 to 0.750 mg/L of Solvent Red 26 in samples with Saybolt colors ranging from +30 to –16. The Saybolt color of the base fuel for samples dyed red with concentration levels equivalent to 0.026 to 0.750 mg/L of Solvent Red 26 is estimated in the Saybolt Color range +30 to –16. The Saybolt Color for undyed samples is estimated in the Saybolt color range from +30 to –16.

1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.