ST10 On-site Fuel Stability and Compatibility Tester


Fuel Stability

Bulk fuel stored for long periods can become unstable the asphaltene content can precipitate out of solution causing the formation of sludge. This has the potential to block filters and pipes, leaving tanks with an unpumpable residue.

The ‘break up’ is dependent on the nature of the liquid hydrocarbons in which the asphaltenes are suspended. If the medium is aromatic (hydrocarbons in ring formation) then they will remain in suspension but if it is paraffinic (linear hydrocarbon formation) the asphaltenes may have a propensity to coalesce into sludge. Once a fuel has chemically broken down there is no way to satisfactorily reverse the process. Precipitated asphaltene cannot be re-dissolved.

Fuel Compatability

On board a vessel, a good way to measure the compatibility of marine fuels, including residual and distillate fuels, is the ASTM D4740 spot test. The ideal percentage mix is 50/50 as this is the worst case scenario.

A drop of the blend is put on a test paper and heated to 100°C. After 1 hour, the test paper is removed from the oven and the resultant spot is examined for evidence of precipitation and rated for compatibility against D4740 reference spots.

AD Systems has developed a portable / on-site / on-boardfully automated instrument for stability and compatibility testing of heavy fuel oil. This portable device is a complete automation of the ASTM D4740 method.



ASTM D4740


  • A complete automated system self-contained in a carrying case
  • Multi-applications instrument, lab, on-site, on-board : Vessel operators , Refineries , Military , Power
  • Fully automated, no training or analytical knowledge required
  • Prevent sludge deposits, failure of fuel handling systems and costly combustion related engine damage.
  • No solvents
  • Removes subjectivity


The ST10 is designed for all types of applications related to fuel stability and fuel compatibility. It is a complete automated system self-contained in a carrying case for, lab, on-site, on-board.


Reported Results Measurement Range
ASTM D4740 rating From 1 to 5
Accuracy Less than one rating
Test mode Programmable:

  • Fuel Stability
  • Fuel Compatibility