ASTM D4740 Fuel Compatibility Tester – AD Systems ST10

ASTM D4740 Fuel Compatibility Tester for On-site and On-board Testing

The AD Systems ST10 ASTM D4740 fuel compatibility tester is a fully automated system for fuel compatibility and cleanliness testing of residual fuel oil and distillate. Developed as a portable, self-contained instrument, the ST10 brings the ASTM D4740 spot test into a single carrying-case system suitable for laboratory, on-site and on-board testing.

The ST10 automates the key stages of the ASTM D4740 procedure, including sample conditioning, filter-paper preparation, spot drying, image acquisition and automated rating. The operator’s direct involvement is limited to sampling, entering the test information and depositing the fuel drop onto the filter paper using the supplied micropipette.

This automation is particularly valuable where the ASTM D4740 spot test needs to be performed away from a conventional laboratory. The instrument is designed for on-board vessel testing, on-site fuel testing and laboratory use, providing a consistent automated workflow within a compact portable system.

ASTM D4740 Spot Test Automation

The ASTM D4740 spot test evaluates a fuel or fuel mixture by examining the resulting spot after controlled heating and drying. With the ST10, the sample is prepared according to the ASTM D4740 procedure before the instrument automatically performs the subsequent test stages.

The fuel or mixed fuel is placed into a disposable vial and conditioned in the built-in oven. The filter paper is automatically positioned and dried at 100°C. Once the sample reaches the required temperature, the operator is prompted to deposit one drop of fuel onto the filter paper using the supplied micropipette.

The fuel spot is then automatically moved into the oven for drying. After the drying period, the spot is moved beneath the CCD camera, where an image is captured and analysed by the dedicated software. The ST10 then displays and stores the result.

This gives the ASTM D4740 fuel compatibility tester a defined, automated workflow rather than requiring the operator to visually assess the spot.

Fuel Compatibility and Cleanliness Testing

The ST10 provides two programmable test modes:

1. Fuel Compatibility
2. Fuel Cleanliness

Results are reported as an ASTM D4740 rating from 1 to 5, with the instrument specification stating an accuracy of less than one rating.

The same automated platform can therefore be used for both fuel compatibility and fuel cleanliness applications, with the test mode recorded as part of the stored test information.

AD Systems specifically describe the ST10 for applications involving residual and distillate fuels, and the product leaflet identifies marine fuels including DM, HSFO, RM, ULSFO and VLSFO.

On-site Residual Fuel Compatibility Tester

The ST10 is more than a laboratory instrument. Its design places the complete ASTM D4740 automated testing system inside a portable carrying case, allowing the instrument to be used on-site, on-board or in the laboratory.

This makes the ST10 suitable for organisations that need to assess fuel compatibility at the point where fuel is received, stored, transferred or used.

AD Systems identifies the following application groups:

• Vessel operators
• Refineries
• Terminals
• Power plants
• Independent laboratories
• Military fuel testing

For vessel operators, the ST10 provides a practical on-board fuel compatibility tester. For fixed facilities, the same system can be used in refinery, terminal, power-plant or independent laboratory environments.

Automated Fuel Compatibility Testing with Image Analysis

One of the defining features of the ST10 is its automated optical assessment.

After the fuel spot has completed the drying stage, a CCD camera captures an image of the spot. The built-in computer and dedicated software then analyse the image and generate the ASTM D4740 rating.

The spot image is also retained with the test result. This provides a visual record alongside the numerical rating and forms an important part of the instrument’s built-in traceability system.

The automated image-analysis approach also reduces the subjectivity associated with manually assessing the spot. AD Systems specifically identifies removal of subjectivity as one of the ST10’s benefits.

ASTM D4740 Results and Full Test Traceability

The ST10 does not simply display a compatibility rating. Test information is saved in the built-in database together with the fuel spot image and test conditions.

The stored result can include:

• Sample type
• Sample ID
• ASTM D4740 rating
• Date and time
• Operator name
• Comments
• Test conditions
• Calibration information
• Instrument serial number
• Software version

The instrument can store up to 100,000 results and export data via four USB ports. This provides a practical record of the test rather than relying solely on a manually recorded compatibility number.

Fuel Compatibility Testing Without Solvents

The ST10 is designed as a no-solvent fuel compatibility and cleanliness testing system. 

The complete automated test system incorporates the sample oven, filter-paper handling, camera, computer, analysis software and database into one portable instrument. The required micropipette and consumables are also supplied with the standard instrument package.