# Compression Air Qualification

Hi,

We have qualified compressed air system as per ISO 8573-1:2010 and considered class 3 for acceptance criteria. As per class 3, the particle size for 0.5 – 1.0 micron should be < 90,000 and for 1.0 – 5 micron should be < 1,000. Attached is the test result for one of the location. Can any one tell me how to measure the particle ranges. Do we have any reference documents to state how to consider the particle counts.

I’m not familiar with ISO 8573-1 (I’m exposing my lack of knowledge). Hopefully I didn’t deviate from requirements.

But, I did follow 14664 guidelines for air quality. We used that to test air quality of compressed air as well. In 14664 there are instructions on how to calculate the ranges for particles. This would require multiple data points at each location. These values were entered into a validated spreadsheet, and the 95% confidence level was calculated using average + 1 standard deviation. This 95% confidence level was what we compared to the upper limit (you referenced <90,000 and < 1,000).

Again we used ISO 14644 rather than ISO 8573-1, so there might be some discrepancy between the two requirements

Ok, let’s analyze your Lasair III particle counter printout - we use the same one. Your have two resulting colomns - Delta and Summ. For example for 0,5 microns raw you have Delta = 3492 particles/m^3 and Summ 6215 particles/m^3. It means, that particle counter has determined 6215 particles/m^3 of size >= 0,5 microns, and actually in range 5,0 - 1,0 - 3492 of the total amount. It easy to check: 6216 - 3492 = 2723 particles/m^3. It directly corresponds to the value, shown in next raw and applicable for particles >= 1,0 micron.

So first your value to compare with ISO 8573-1 requiremnets it’s definitely Delta between 0,5 and 1,0 - first raw and first resulting colomn. This value is 3492 particles/m^3 and your result is ok (it less then 90 000 and even enough for Class 2 <=6000 particles/m^3).

Then another range. A little bit more complicated, but also not too much. The required range is between 1,0 and 5,0 microns. And particle counter suggest more detailed info - Delta between 1,0 - 2,0 microns and between 2,0 - 5,0 microns - you need simply to add them - in your case it will result in 1350 +1097 = 2 447 (in this case it is not enogh for Class 3 and only corresponds to Class 4 < = 10 000 particles/m^3).

Actually it’s too much for this range - do you utilize high pressue diffusor: http://www.prager-elektronik.at/datenblaetter/PMS/HPDIII.pdf

What the system is that - which compressor, which filters, which distribution system? Was is treated after construction - cleaning, passivation? Which the intended use - instrumentation air for valves or for sterilizing filtration of aseptic products?

1 Like

Thank you for the response.

Thank you for the response.

HI,
Below is the data that was generated for compressed air system in 2014 using different model of particle counter.
If we compare both in terms of particle sizes on the left side, in 2014, the particle counter generated data for 0.3, 0.5, 1.0, 5.0, 10.0 & 25.0.
Whereas the recent data shows for 0.5, 1.0, 2.0, 5.0, 10.0 & 25.0.

The doubt/ question: If the particle count had the option of reading the particle count for 1.0, 2.0, 3.0, 4.0 & 5.0 microns, then each individual will have counts and adding this values for range between 1.0 to 5.0 micron will ultimately result in higher values. As in the data generated in 2014, the particle counter had the reading for 1.0 & 5.0 micron. And since there is no data for 2.0 micron, otherwise which could have resulted in higher values.

With this doubts, I request you to further clarify on this.

I’m not sure I understand your question. Is your question “Do we add the particle sized together to get the total results”? If that is your questions, then the answer is “No”. The values given are for particles with a minimum size. So results for 0.5 include all particles for 0.5, 1.0, 2.0, 3.0, 4.0, AND 5.0, etc… The particle reader does not read particles that are exactly that size and only that size, it counts particles that are at least that size. Please double check with the instruction manual for the instrument you are using, though.

Hi ,
as per the ISPE guidance on compressed gases, the limit for particle count shall be as the grade (class) of area, where POU is located