The leak detection determination for DOP high-efficiency liquid filter is based on the core standard of **≤0.01% penetration rate (leakage rate)**. It is accompanied by repair and re-test rules, which need to cover the filter material, seal, and frame, and meet the specifications such as ISO 14644-3 and GB/T 6165-2008. Here are the determination criteria and practical key points:
Core determination indicators
Penetration rate threshold: The continuous and stable penetration rate of all scanable points of the filter ≤ 0.01% (that is, one ten-thousandth of the upstream concentration), any point exceeding this threshold is judged as不合格， and it needs to be marked for repair or replacement.
Scan coverage range： Filter material surface， filter material – frame bonding area， frame – liquid tank sealing surface， liquid tank – static pressure box / enclosure joint， frame joint seam， etc.
Detection parameters： Scan speed ≤ 5cm/s， probe distance from the filter surface is approximately 25mm， line overlap ≥ 10mm； the upstream aerosol concentration is stable at 10–20μg/mL (or meets the instrument linear range).
Repair and re-test rules
| Project | Qualified upper limit | Re-test requirements |
| Single repair length | ≤38mm | After repair, a re-measurement of the entire area was conducted, and the penetration rate remained ≤ 0.01% |
| Cumulative repair area | ≤ 3% of the filter material area | If it exceeds the limit, it must be replaced entirely. |
| Repair method | Special sealant / patch, compacted without air bubbles | Must not affect the sealing of the liquid tank and the uniformity of the airflow |
Qualification determination process
Upstream dust emission and concentration calibration: Confirm the stability of the upstream concentration, and perform zero adjustment and linear calibration on the spectrophotometer.
Zone scanning and data recording: Scan each zone, record the penetration rate at each point, and mark and locate the abnormal points.
Result determination: If the penetration rate of all points is ≤ 0.01% and the repair is compliant, it is determined as qualified; otherwise, it needs to be repaired/ replaced and retested until qualified.
Report and traceability: Record the equipment number, detection date, upstream concentration, maximum penetration rate, repair location / area, retest results, etc., and archive for retention.
Key standards basis
ISO 14644‑3: The maximum penetration rate of scanable high-efficiency filters is ≤ 0.01%.
GB/T 6165‑2008: The on-site leak detection penetration rate of high-efficiency filters (0.3μm) is ≤ 0.01%.
FDA/GMP: The pharmaceutical industry requires that filters and seals have no leakage and the penetration rate is ≤ 0.01%.
