can any body tell me the basic difference b/n ferrographic testing,emission spectroscopy and particle count in case of lube oil.
good luck
Anurag

Ferrographic testing sees mostly ferrous particles, not the other stuff. Direct reading ferrography quantifies the particle count of these ferrous particles in a small (<5um) and large (>5um) size range. Sometimes called wear particle concentration meaning some people think it is a good thing to track to see machine wear. Analytical ferrography costs a lot more and involves a human examining these particles with a microscope to attempt to characterize their nature and orign.

Emission testing testing includes a variety of technologies that will identify the atomic content of the small particles. Tests include ICP, RDE (both limited <5 um) and RFS (<10um). One thing this provides is an indirect check on the type of oil (are the expected addivites present). Various elements identified in these small particles might gives clues (Fe may be rust or steel wear, Cu may be brass wear, Si is usually contamination).

Particle count is primarly to check for contamination. Usually reported as an ISO cleanliness code. Particle sizes grouped into >4um, >6um, and >14um

Good explaination Mr Pete. I don't think that many people realise the limitations of particle sizes when haveing a spectroscopy report.

This alone has little chance of picking up excessive worm wear in a worm/wheel box does it not? It all goes to prove you shouldn't just accept the first suite of tests your lab offers you.

tthew,

You are correct in judging that the end users typically don't know that the spectroscopy report doesn't give the whole picture. I just finished doing a round of cold calls to wastewater industry facilities and asked that question and most of them didn't know the limit was that small.