FDM 6000 - for Fuel Dilution Measurements

Direct fuel dilution measurements are possible with Spectro scientific's FDM 6000, which is completely portable because of its built-in battery.

The FDM 6000 Series fuel dilution meter directly measures the fuel dilution percentage in engine oil.

The FDM 6000, a portable battery-powered fuel dilution meter, can ascertain the fuel dilution concentration in an oil sample within minutes. It punctures the cap of a disposable sample vial and extracts the headspace inside, using a novel, patent-pending fang design.

A surface Acoustic Wave (SAW) sensor that is flown over by the headspace detects fuel vapor within a detection range of 0 to 15%. In motor oil, it can identify diesel, gasoline, or jet fuel. It adheres to ASTM D8004, which outlines the "Standard Test Method for Assessing Fuel Dilution in Operational Lubricants Using Surface Acoustic Wave Sensing."

Principle of Operation

Henry's Law: The concentration of fuel vapor present in the head space of a closed bottle at equilibrium is proportional to the amount of fuel present in solution. Image Credit: AMETEK Spectro Scientific

By taking a sample of the "headspace" in a vial or bottle, fuel dilution meters use a Surface Acoustic Wave (SAW) vapor sensor to determine the fuel concentration in spent oil samples. The apparatus assumes that the amount of fuel in the oil sample and the fuel concentration in the headspace vapor are directly correlated (based on Henry's Law).

A piezoelectric substrate with an interdigitated electrode lithographically patterned on its surface makes up a SAW sensor. The polymer coating on the SAW sensor's surface was selected to provide a particular level of solubility for fuel vapors. The fuel component's reversible absorption into the polymer serves as the detection mechanism.

Surface Acoustic Wave (SAW) Sensor. Image Credit: AMETEK Spectro Scientific

FDM Sampling system. Image Credit: AMETEK Spectro Scientific

Fuel contamination will seep into the polymer coating when it comes into contact with the SAW sensor surface. The amplitude and velocity of the surface wave change in tandem with the mass change brought about by this absorption into the polymer. The vapor absorption into the polymer coating changes the Rayleigh wave velocity, which changes the oscillator frequency in a self-resonant oscillator circuit. This frequency shift is the basis for detection.

The FDM calibrates the system to a particular fuel/oil matrix and ambient temperature using a one-point user calibration. When room temperature varies by a few degrees, it is advised that the FDM be calibrated using a reference sample because fuel vapor concentration fluctuates with environmental and sample temperature.

When running samples, it is best practice to calibrate the FDM at the same room temperature. Spectro Scientific sells standard oil with known fuel dilution that can be used as a reference, or the user can mix their sample with known fuel concentration. It is possible to store calibration for later use.

Key Features

• Complies with ASTM D8004: “Standard Test Method for Fuel Dilution of In-Service Lubricants Using Surface Acoustic Wave Sensing.”
• Innovative headspace sampling fang design ensures excellent repeatability (<= 5% RSD)
• Direct fuel dilution measurement within a 0.2 to 15% fuel dilution range
• It only takes a minute to complete
• Small sample volume – only 0.5 ml of oil used
• The use of up to three stored calibration profiles is made possible by the onboard memory
• Sample ID entry and data file export via USB cable
• Disposable FDM vials eliminate carryover contamination
• An optional hard case for transit that is lightweight and battery-operated
• An audio prompt feature that walks operators through testing

Model Comparison

Source: AMETEK Spectro Scientific

FDM 6000 Fuel Dilution Meter. Video Credit: AMETEK Spectro Scientific