Fluorescence

Relative measurement technique

Fluorescence is a relative measurement technique. There are many factors that affect the level of light emitted by the oil:

• Not all oils fluoresce- generally aromatics do and aliphatics don’t.
• Different oils give different levels of emitted light for the same ppm of oil.
• Droplet size affects the level of emitted light.
• Some chemicals used also fluoresce.
• Oil fluorescence is not a simple linear equation.

In order to ensure that all Advanced Sensors analyzers are as accurate as possible each analyzer is calibrated to the expected ranges,  with a sample of the customers own oil where provided. Pre-calibration with the customers own sample is particularly important for higher oil ranges. Advanced Sensors can provide measurement up to 20,000 ppm.

Overcoming issues

• Use of ultrasonics ensures that a homogenised sample is provided, giving a reference point should there be any fluctuation in oil droplet size, as well as keeping the sensor clean.
• Creation of customer specific oil  curves for pre-defined ranges overcomes issues associated with different oil types and their relative strengths.
• Use of a spectrometer means that Advanced Sensors can detect a change in oil type or the presence of fluorescing chemicals and can adjust for them.
• As the emitted fluorescence is based upon the level of the excitation light it is critically important that the output of the light source remains constant , otherwise the analyzer will require periodic recalibration. Advanced Sensors uses a laser to provide a long life consistent light source. The technique is often called LIF (Laser Induced Fluorescence).