Standard test: ISO 3104
Measured in cst at 100 °C


 Accurate measurement of the viscosity is essential to be able to dictate the temperature to ensure the pumpability and circulation of the fuel and avoid damage to fuel injector systems. Minor overshoots can be usually be re-corrected with increased pre-heating in settling and day tanks. The crucial issue it that that the viscosity controller must be able to quickly adjust the final heater to bring final viscosity deviations into line with those needed for the fuel injection. It is crucial that the viscosity of the fuel as it arrives at the injector be adjusted to ensure a designed spray characteristic as it come through the nozzles.

The questions to ask are:

  • Can the viscosity controller make the necessary adjustment to cope with the slightly higher viscosity?
  • Can the final pre-heater system compensate for the difference in viscosity prior to point of injection with an increase in temperature?

If so it is recommended that you take this approach and so avoid potential incompatibility risks when blending with marine Diesel oil. If blending is necessary than the buyer should normally expect that all additional costs involved in taking the additional MDO are for the supplier's account.

  • Poor atomization from incorrect injection viscosity can hamper or even prevent ignition. Adjust viscosity controller.

In the case that the differential between the viscosity required and that shown by the sample is significant, usually then either of two possible scenarios may exist:

  • An unrepresentative sample.
  • An inhomegenous batch of fuel.

In either case resampling is recommended. In the second instance see the section on Inhomegenity.