#cleanroomafterhours # 8 Particle monitoring in the cleanroom – is it a piece of cake?
This week we will take up the subject of particle monitoring, or rather we will ask the question whether it is possible to “spoil” such a measurement?
The ISO 14644 standard indicates the need to monitor the particle cleanliness of the cleanroom zone. It provides information on the number of sampling points, how to perform measurements and how to deal with deviations.
So where’s the snag? What can you “spoil” here?
Answer: In the way of measurement.
It happens quite often, during training meetings, that you inform about the particle number measurements very often for the cleanroom you work in. The tests are performed every two weeks, sometimes more often.
One could say- WOW – weekly measurements, weekly reports, weekly supplementing the trend analysis – with large areas, it would actually be necessary to have a separate person dedicated only to this activity;)
Sometimes you take the sample in one point in the room and if the result is negative – you repeat the measurement, but in places designated by you as “critical” – i.e. at the door, at the ceiling ventilators, etc.
Sometimes the amounts determined by the standard, let it be 16 pieces, are divided into measurements carried out at weekly intervals, four measuring points per week.
Finally – sometimes you collect the correct number of sampling points in a given test, but the sampling points are designated only around the technological line and do not cover the entire room.
Each of the above-mentioned situations is an example of improperly implemented particle cleanliness monitoring.
This means that the results obtained in this way can NOT be used to determine the cleanliness class of the room.
So how do you get it right?
We always collect as many points as indicated in the table in the standard at the same time – so as to maintain uniform environmental conditions. Only then the results are comparable and can be used for trend analysis.
We divide the room area into X equal areas and locate the collection point in each of them. X is the total number of points given in the ISO norm. For subsequent measurements, the point in a given area can be taken from another place 🙂
We ALWAYS perform the tests at the height of the working area – there is no point in examining the particles at the door, at the ventilator, while performing one measurement “somewhere” in a representative place in the room. Only the execution, in accordance with the ISO standard, of the exact number of samples taken, ensures that 90% of the room meets the requirements of the cleanliness class. Then we don’t have to include statistics in our calculations;)
Always position the isokinetic probe in the direction of incoming air.
The time intervals between individual measurements are determined by means of a risk analysis and the assessment of requirements for the technological process.
Successful measurements!
#CRK #ISO1464