Setting-up a cleanroom involves making decisions. Which suppliers? Which clothing? Several articles in this issue of Monitor tackle these questions.
The society has recently held the AGM - Lynn Morrison reports.
Alas - Carol Gentle is leaving us.Carol has worked for the society for four years-always with humour-but has decided to move to sunnier shores. Australia this is your gain. Best wishes from all at SC.
A big thankyou to Mr Jack Diamond for his letter.
Dear Sirs,
Further to the article on the validation of clean rooms by particle counting from Duncan Smith, I would add a few comments.
Programmes incorporating Fed. Std. 209e airborne particle count determinations are carried out in the ‘at rest’ conditions for regulatory authorities. To quote Fed. Std. 209e 5.1.2.1. The status shall be reported ‘as built’, ‘at rest’, ‘operational’ or as otherwise specified". Therefore we do not understand 209e to apply solely to ‘in use’ conditions.
The number of locations the quoted example is unfair as a Class 100 (M3.5) standard room, attaining a 95% UCL requirement, would not normally be of non-unidirectional airflow. I believe the statistical methodology to be founded on the application of unidirectional air flows for Class 100 and better as is evident from the table in the article. As is shown within the article, unidirectional rooms do reflect both class and the discriminating size chosen in the sampling equations in the sampling volume requirements.
The statistical methods of 209e provide a realistic method of evaluating clean rooms, allowing for the practical reality of minor excursions outside the stated parameters.
The measurement of airborne particle size always was subject to interpretation and interpolation, except of course in the case of perfect particles such as calibration spheres which are rare visitors to controlled clean spaces!
Editor - Comments please