Don’t just test “convenient” spots. Use the statistical grid method from ISO 14644-1 Annex A. For non-unidirectional airflow, include and air returns .
Based on field experience, here are five pitfalls to avoid when applying the standard:
Note: Annexes H (visual inspection) and J (filter bypass leakage) are also available but less frequently used.
Note: Some regulated industries (e.g., EU GMP) may require more frequent testing.