SOOT: Percentage vs FTIR value

Augusto,
You need to ask the lab to tell you what test they are running to get the the 2%. The problem with the FTIR and using the absorbance numbers to correlate with %soot is that you don't know the frequency range and the area that the FTIR software is using to assess the abs numbers. For example if they are using the JOAP-TSC formulas then the JOAP manual says that 30abs correlates approximately to XX %.

The simple answer is that trying to compare the 2 different labs who report on different scales after performing different tests, will not work.
But you should be able to get the lab doing the FTIR to provide you with an approximate % soot but you won't be able to go the oher way.

regards.......

There is one single important factor which should be seriously considered for the FTIR detemination of soot. Often the slope of the IR spectrum at 2,000 wavenumber, designated to evaluate soot content in the used oil, is not only related to the quantity of soot, but also it depends on the size and size distribution of soot particles. So it is difficult to calibrate FTIR spectrometer with soot-containing oil for practical determination of soot-laden used oils. In other words, correlation of FTIT soot readings with gravemetric determination of soot concentration is questionable.

FTIR is the most economical and fastest way to
quantify soot loading.Trending the soot data is
the best way to interpret.The elevated soot levels signals combustion related problems.FTIR can be best used as a screening tool.Usually
soot increases viscosity,depletes dispersant and anti-wear additives.Excess soot loading accelarates liners,rings,bearing wear.

Bala.

After lots of test we have found what you just told, there is no direct correlation between gravimetric and FTIR soot measurement.

The best is to define an analisys method and then keep it as the standard, trending data of the lube oil from the very begining of use.

Thanks for your reply