How to tell about the level of concentration of ferrographic particles in a ferrogram in terms of a rating number? I know that there is one who rates with weak, medium or strong, and other like Predict which rate with a scale from 1 to 10. Where can I find written rules about this subject?

There aren't any written rules. Each company has developed its own normal-to-critical rating system. Then, it's up to the individual interpreting the ferrogram to assign the rating they feel is most appropriate for the particles in question.

If you're looking for a systematic training reference for ferrography, try the Wear Particle Atlas CD-ROM from Lubrosoft.

Mark Smith
Analysts, Inc.

How do you rate the particles in your company? Is it by the percentage of the ferrogram covered by particles? And do you use dilutions? As about the CD, I have it but I don´t have the operating key to open the program. Contacting lubrosoft hasn´t made any result. Thanks

I have some difficulty in distinguishing sand particles from lube degradation. I see aglomerated particles envolving the rubbing wear which are translucid and by polarized light are not shinning but not dark neither. What do you think? I can provide some pictures.

particle rating in analytical ferrography is purely based on subjective scale severity index these index could be determined by using type of machine being monitored, quantitative results, size of the particles, concentration & orientation of the particles, composition & surafce structure of the particles. each has significant contribution size & concentration will give severity of wear. surface structue & composition will give source and some times root cause of wear.
sensitivity of the equipment plays key role in deciding the severity scale. gear boxes(high speed rough running) have different strategy when campared to clean running sensitive turbines.

There is no standardized method of setting severity levels for analytical ferrography.

My company no longer does analytical ferrography as a service. When we did we had three scales, one for wear particle concentration, one for max wear particle size and one for contamination concentration.

The main types of equipment we would analyze were diesel engines, fd/id fans, gearboxes, hydraulic systems, turbines and pumps.

At first, we used the DR Ferrograph as the "pass/fail" standard for a sample, if the DL/DS readings went up significantly, or were considered high for our set standards, then we carried out an AF. Later, we supplemented the DR with a pore blockage particle counter, and used both technologies as "pass/fail" standard.

AF criticality levels were set based on the wear particle concentration in combination with max wear particle size. If either or both went up significantly, then the alarm bells went off. The contamination concentration index was used to confim the particle count level increase.

Regards

Steve

Steve

Why do you no longer use ferrography? Did you replace it with another technique?

Regards