HEPA is still the default. ULPA belongs where particle counts, sterility or cell culture leave no margin. Here is how we specify both on the same Weiber worktop.
1. HEPA vs ULPA is a retention claim
HEPA H14 retains 99.995% at MPPS. ULPA U15/U16 goes further. Specify ULPA when ISO 4 or sterile fill work is in the protocol — not because the brochure looks better.
2. Two-zone worktops
A two-zone layout keeps dirty loading off the sterile plane. Ask for the ULPA bank over the work zone only if the return path is already HEPA-filtered.
3. Velocity and smoke
0.45 m/s ± 20% at the work plane is typical. Confirm with a smoke test after filter install, not only at factory.
4. What to put on the PO
- Filter class and MPPS
- Work-plane velocity
- Pre-filter and Magnehelic
- IQ/OQ with particle counts
5. When HEPA is enough
Routine media prep and device assembly usually stay on H14. Send the ISO class and we will specify the cabinet.
