FAQ - Pharmaceutical/Life Sciences Particle Counting

IsoAir Particle Counting Sensor

Question
If performing particle counting with tubing connected to the isokinetic probe, is there a suggested timeframe to change the tubing due to possible particle hold up?

Answer

There is no real recommendation for tubing change, in essence the tubing is drawing through "clean" air, and so would not be exposed to the levels of contamination one might see if we were sampling outside air.

From experience, we have tubing installed into fixed systems that have lasted over 15 years and are still clean.

A test to verify tubing would be to attach a filter directly to the inlet of the particle counter, take a 5 minute sample and generate a baseline reading, then using the same filter attach the tubing (no more than 2 m - see An Analysis of Acceptable Particle Losses in Tubing ) and attach the filter to the end of the tubing - the results should be the same or no more than a 10% difference. The numbers are 0, 1 or at worst a 2, so it become difficult to state in absolute terms what error you mat be seeing as the numbers are very small. However as the numbers you are likely to see in Class A, B or C are well in excess of the 1-2 values with a filter, the relative error is extremely small.

If you do have contaminated tubing, i.e. the expected counts with tubing and filter are greater than tolerated, then the solution is to discard the tubing and replace with new - the chance of cleaning contaminated tubing is very small. New tubing will need purging through for a few minutes to ensure any particles from shipping has been dislodged and are out of the system.