PQ index and wear particle monitoring

http://www.practicingoilanalysis.com/article_detail.asp...ookgroup=OilAnalysis

Hi,

The PQ measures all magnetic/ferrous material in a sample. Its advantage is that all metal in the sample regardless of size is measured (a problem with ICP and sometimes the Spectroil M).

In my experience the PQ mimics the Fe (from the Spectrometer) almost exactly.

What if the PQ and Fe don't match?? An example - PQ is high and Fe is low we can assume in this case that the Ferrous metal in the sample is comprised of large metal pieces which the ICP or Spectrometer have not picked up but are being read by the PQ. This scenario might occur at the onset of failure e.g. a chipped gear tooth results in large metal particles not picked up by the ICP immediately.

The PQ should not be used as a substitute for the Spectroil M / ICP.

Anyone correct me if I'm wrong but I think measurement is in miligrams per litre. Or PPM.

I echo Andrew's info except that the PQ Index can be considered unitless. It is an index and thus has no units. It is very useful to trend and use to determine if further analysis is required i.e. an actual visual debris analysis. But keep in mind it only measures "magnetic" metals so one could have a low PQ but still a lot of non-magnetic metallic particles present i.e. aluminium, brass, bronze etc. The good thing is that this is a rare occurence as most systems have at least one iron-based wearing part.

Hi,
The advantage of PQ index is obvious as a measuring method of magnetic/ferrous metallic particles. But what standard we should execute to acquire a measurement of PQ index? In another word, is there such a accepted standard by far?
Thanks for any insight you can provide.

And rust has little to no magnetic value,

And what has a high magnetic flux, there surely are mines mining stuff with elements which have higher magnetism than unrusted iron....

And generally I have found that:-

Fe>>PQ then magnetised particles are small in size

Fe~PQ then ~7um ave particle size (ICP max. size)

Fe<<PQ then ave size are sizable

It’s really great posts.

hello

I'm implementing the PQ index test in my lab in Rio de Janeiro, my equipment calibration and is giving good response in the calibration but to buy samples to another laboratory in the USA, get higher results. EX USA result: 5, Result Rio: 30, this trend is repeated for all samples.

Other samples the U.S. finds zero index PQ and my lab finds 20, 25 ...
What can be happening?

thank you very much