Following the publication of the new Annex 1 an uncertainty regarding the maximum allowed tube length leads to additional parts in every risk assessment. Annex 1 mentions 1 m as the maximum length allowed for newly designed and also existing systems. The main question is now: Where is this limit of 1 m coming from and is it fixed? Or is there a possibility to use longer tubes? If the answer to the latter question is yes, how can longer tube lengths be justified?
The presentation covers not only the topic of tube length but extends also to the need of high counting accuracy and the influence of the particle size on the particle motion within the tubing. Finally potential error sources of particle counting are discussed.
Last but not least some content of the new ISO 14644 Technical Report 21 will be presented including some decision scheme to assess the actually used tubing length.
A completely new qualification is not necessarily required if the tubing length differs from 1m. If it is the instrument manufacturers can provide supporting information or even carry out comparison measurements regarding the particle loss. Our expert will be happy to guide you through this complex topic within our presentation.