Buyer guide
Air shower and pass box selection
An air shower blows loose particles off a gowned person at an entry, and a pass box moves materials through a wall without opening both sides at once. EU GMP Annex 1 and USP <797> both bar the two doors of an airlock or pass-through from opening together, and Annex 1 requires interlocks into Grade A and B areas.
By ZY Cleanroom · Updated · Sources at the end of the page
What each device does
EU GMP Annex 1 does not mention air showers. Its personnel route is a changing room that works like an airlock (paras 4.1 and 4.12). Decide on an air shower from your own contamination risk, not from the standard.
| Device | Job | Rule from the sources |
|---|---|---|
| Air shower | Removes loose particles from gowned people | Not named in Annex 1. Build the doors as an interlocked pair, like an airlock. |
| Static pass box | Moves small items through a wall | Doors never open together; no air supply |
| Dynamic pass box | Same, with a filtered air flush | Annex 1 gives flushing with filtered air as an example of protection |
| Material airlock | Moves carts and large items | Only approved items into Grade A or B, with cleaning and disinfection |
Interlocks and pressure
FDA's 2004 guidance says airlocks and interlocking doors help control air balance. These are the written rules.
| Item | Rule | Source |
|---|---|---|
| Doors into Grade A or B | Interlock; doors not open together | Annex 1, para 4.13 |
| Doors into Grade C or D | Visual or audible warning, as a minimum | Annex 1, para 4.13 |
| Door delay | Time delay between close and open, where needed | Annex 1, para 4.13 |
| Pharmacy pass-through | Both doors never open together; doors should interlock | USP <797>, 4.2.1 |
| Pressure step | 10 Pa minimum between adjacent grades, guidance | Annex 1, para 4.14 |
| Anteroom to unclassified | 0.020 in. w.c. minimum, about 5 Pa | USP <797>, 4.2.5 |
Size an air shower by throughput
The sources set no nozzle velocity or cycle time. Ask each supplier for velocity at the nozzle exit, measured with a calibrated anemometer, and the cycle time per person.
Example only, with assumed numbers. At an assumed 30 s cycle, one person at a time, 20 people entering in 15 minutes need 20 × 30 = 600 s, or 10 of the 15 minutes. If your own figures leave little margin, compare a second unit or a tunnel type.
Filters and maintenance
Air showers and dynamic pass boxes carry a final filter. Ask for its class under EN 1822 and whether it can be leak tested in place. ISO 14644-3:2019 clause B.7 describes the method for installed filters.
A pass box does not replace the cleaning rule. Annex 1 asks for cleaning and disinfection of items moving into higher grades, commensurate with risk.
Put these in the data sheet
State each device, the grade on both sides, the door interlock type, the airflow or flush, the final filter class, the pressure target, peak people per hour and the largest item to pass. Add the alarm and bypass rule for a power cut.
What goes through the pass box
Annex 1 allows only items on an approved list, assessed during validation, into Grade A or B through an airlock or hatch. An unapproved item needs a recorded exception and a risk assessment.
USP <797> bars shipping cartons and corrugated or uncoated cardboard from classified areas. It also says transport carts must be cleanable, and must be cleaned and disinfected, casters included, before crossing from the dirty to the clean side of the anteroom.
Who approves the room
Your regulator judges the facility, not the contractor. The contractor builds to your data sheet and supplies test records. To have a room list reviewed, send it to ZY Cleanroom, a cleanroom design-and-build contractor with its own panel factory in Tianjin, China.
Questions
Common questions
Is an air shower required for GMP?
The text of EU GMP Annex 1 does not mention air showers. It requires airlock-type changing rooms.
Can both pass box doors open at once?
No. Annex 1 and USP <797> both bar it. Annex 1 requires interlocks into Grade A and B.
Static or dynamic pass box?
Annex 1 says hatches should protect the higher grade, for example by flushing with filtered air. Decide by risk assessment.
What pressure should a pass box hold?
Follow the room cascade. Annex 1 gives 10 Pa minimum between adjacent grades as guidance.
How much does an air shower cost?
This guide gives no figure, because price follows the specification. People per cycle, number of doors, body material, nozzle count, filter grade and controls all move it. To compare offers, send each supplier the same data sheet and ask whether freight, installation and the filter test are included.
What is the HS code for an air shower?
US customs ruling NY 898508 of 1994 placed an air shower with a HEPA or ULPA filter under subheading 8421.39, filtering or purifying machinery for gases. That ruling is old and covers US imports only. Ask your importer or customs broker to confirm the code in your country before you ship.
Related guides
- How to audit a cleanroom panel factory, on site or by video
- What a cleanroom costs to run: energy, filters and testing
- How long does it take to build a cleanroom?
- How to Import a Cleanroom from China
- Turnkey cleanroom contractor
- Room list builder
Sources
- EudraLex Volume 4, Annex 1: Manufacture of Sterile Medicinal Products (published 25 August 2022, applied from 25 August 2023; checked 31 October 2026)
- FDA, Guidance for Industry: Sterile Drug Products Produced by Aseptic Processing, Current Good Manufacturing Practice (September 2004, nonbinding; checked 31 October 2026)
- Washington State Department of Health, Pharmacy Self-Inspection Worksheet, 2026 USP 797 Sterile Compounding Addendum, DOH 690-296 (January 2026), which reproduces USP <797> text by section; checked 31 October 2026
- ISO 14644-3:2019, Cleanrooms and associated controlled environments, Part 3: Test methods (published August 2019; contents list checked 31 October 2026)
Project enquiry
Send what you have
A room list, a floor plan or only the floor area is enough to start. After you submit, send drawings by email or WhatsApp.
We reply by email within one working day. We can sign an NDA before you send drawings.
WhatsApp +44 7962 561184 is our UK number for export enquiries. The factory is in Tianjin, China.
Email: [email protected]
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