Correlation Studies
| Study | Type of Artificial Leak | CCS | Studied Range/Size | Artificial Leak with No/Zero Ingress | Equivalent He leak Flow for Zero Ingress (mbar * L/s) | Critical Leak Size: Substantial increase in risk/frequency for microbial ingress (% of tested units) | Critical Leak Size: Equivalent He leak flow for substantial ingress (mbar*L/s) | Reference |
|---|---|---|---|---|---|---|---|---|
| Morical et al.(outside-in) | Wire in rubber stopper | 15 mL vial | 10–120 µm | 15 µm | 1.3-1.8E-05 | 20 µm | 2.2–2.8E-05 | (5) |
| Stainless-steel orifice disks | 15 mL vial | 0.5–15 µm (FED) | 2 µm | 1.4E-03 | 4 µm | 6.1E-03 | ||
| Mathaes et al.(outside-in) | Wire in rubber stopper | Vials of undefined size | He flow rate10-8 to 10-1 | ND | 4E-07 | ND | ≈1E-05 | (13) |
| Burrel et al. (no He leak determinations) | Fused silica capillaries | 5 mL vials | 2–75 µm (ID) × 30 mm L | 5 µm | 3.7 E-06b | 10 µm (70%) | 2.3E-05b | (14) |
| Kirsch et al. (inside-out) | Glass pipettes | 10 mL vials | 0.1–10 µm | 0.2 µm | 2.2 E-07 | 0.4 µm | 2.0E-06a | (3) |
| Keller (no He leak determinations) | Nickel microtubes | Bioaerosol test chambers of 8 cm (h) × 5 cm (d) | Nickel microtubes (liquid filled) 2–50 µm ID × 7 mm L | 2 µm | 3.1E-07b | 5 µm (depending on Δp)): at ± 20.7 kPa)) | 2.2E-05b | (16) |
| Gibney (no He leak determinations) | Nickel microtubes | Bioaerosol test chambers of 8 cm (h) x 5 cm (d) | Nickel microtubes(air filled) 2–50 µm ID × 7 mm L | 5 µm | 2.2E-05b | 7µm (at −34.5 kPa) | ND | (17) |
| Ravishankar et al.(no He leak determinations) | Tungsten wire (withdrawn prior to challenge) | Polymeric trays (335 mL) | 10–200 µm (6 mm L) | ND | ND | 10–200 µm | ND | (18) |
| Disk pinhole (plastic / steel) | Polymeric trays (335 mL) | 5–50 µm (0.7 or 0.05 mm L) | ND | ND | 5–30 µm | 4.3E-03c |
Note: CCS = container closure system; FED = flow effective diameter; ND = not determined.
↵a Mid value of published range was chosen.
↵b He leak flow rate from authors used to provide an order for typical He flow rates for such artificial leaks (same dimensions with fused silica capilleries).
↵c Average He leak flow rate for steel disk in vial measured by outside-in method in this study (n = 25 results, span 0.99).