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PQ – Measuring abnormal sized ferrous / iron wear particles in lube oils

PQ PQ   Measuring abnormal sized ferrous / iron wear particles in lube oilsPQ – this is a dimension absent value indicating the amount of ferrous (i.e. Iron, Steel, Cobalt or Nickel – magnetic) material in the sample. Standard Iron results are performed by ICP (Inductively coupled plasma) and measures particles ideally less than 5 to 10µm. By comparison the width of a human hair is 80µm. Therefore large ferrous particles that can be seen by eye will be underestimated by ICP. Hence the PQ method detects small and large particles and the test can be used with iron to detect the abnormal and normal sized particles.

A great limitation is this only applies to magnetic materials so other wear elements cannot be tested to the same degree. So this usually means just iron and equally, iron that is in a magnetic form because rust for instance is not magnetic. However new advances in technology such as the LubeWear method make this a thing of the past and the benefits of small and large particle testing can be detected with the LubeWear method

Ferrous debris – is a similar test to PQ but instead of it being unitless the test calibrated against known concentrations of magentic iron giving a true reading in ppm of ferrous material but it too has the same limitations of only detecting magnetic particles.

Common Causes Potential Result Potential advice
High PQ result compared to Iron ICP result Abnormal wear processes:
  • Abrasive contaminants
  • Misalignment
  • Overloading
  • Poor lubrication
  • And many more.
  • Machine failure
  • Reduced component life
  • Loss of production
 Further investigation of oil/filter by laser net fines or ferrography to determine cause

Find out how wear metals, ferrous debris, contamination elements, wear particle quantification index (PQ / PQI) and additive metals are tested below, what each element on a report means and how to diagnose which components on failing in the video below.

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