Sweeping Flat Electrode

A graphite flat electrode is used to hold oil or grease sample. The flat electrode is fixed on an XY sweeping wagon or table. While sparking, the flat electrode is continually moving under the spark fireball until the sample is burned entirely. Spectrometric oil analysis of multi-elements is so realized.

 

Advantages

 
1) Capturing large wear metal debris: the debris particles, no matter how large, “sit” on the flat electrode and are fed into a fireball. There is no limitation of particulate size or weight. The emissions of all metal particulates are registered by AES spectrometer. Apparently, RDE-AES and ICP-AES cannot achieve this advantage.
 

 2) Grease analysis: because sample “sits” on the flat electrode, and is fed into a spark gap by the wagon, the viscosity of the sample is no longer a concern. Any kinds of lubricant, including grease, can be sent into a spark for testing. This eliminates tedious wet chemical methods to treat a grease sample for multi-elemental analysis.

 

3) Burned or sparked oil or grease is no longer recycled into its holder to be re-sparked during testing, such as encountered in RDE-AES oil analyzer.

Why does RDE-AES under-report large wear metal particulates in used oil analysis?

 
Because of the gravity of wear metal particles, large particles cannot float in a standing sample holder for a certain time. They settle down to the bottom very soon. The oil is brought into spark by disk rotating. Such motion is incapable of digging up the particles hiding on the bottom. This is physics! Therefore, the rotating disk serves as a perfect filter to exclude large particles from being reported.
 
This doesn’t mean there is no way to improve the RDE-AES! At least, there is a way: set up a RDE-AES device in a zero-gravity zone, such as in International Space Station, where large wear metal particles are always suspending in your sample holder. But don’t forget to bill your customers a lot of their fortune!  
 
So do for ICP-AES and other methods that rely on the suspension of large particles in oil. Remember the physics.

SFE-AES Method was patented by COA