Buyer guide
Static vs dynamic pass box: how to choose
A static pass box is a wall hatch with two doors that cannot open together and no air supply of its own. A dynamic pass box adds a fan and HEPA filter that flush the chamber with filtered air, the kind of flushing Annex 1 gives as an example for pass-through hatches that protect a higher-grade room.
By ZY Cleanroom · Updated · Sources at the end of the page
What the texts say
GB 50073-2013 defines a pass box as an opening in a clean room partition for moving materials and tools, with a casement on each side that may not be opened at the same time (term 2.0.22). None of the texts below calls for a dynamic box in every case. Annex 1 gives flushing as an example. The choice stays with the owner's risk assessment.
| Point | Text | Source |
|---|---|---|
| Both doors open together | Not allowed: USP says never at the same time; Annex 1 says should not open simultaneously | USP <797>; Annex 1 para 4.13; GB 50073-2013 term 2.0.22 |
| Interlock | Interlocking for airlocks leading to grade A and B; visual or audible warning for grade C and D; USP says doors should interlock | Annex 1 para 4.13; USP <797> |
| Air flushing | Hatches should protect the higher grade, for example by flushing with an active filtered air supply | Annex 1 para 4.12 |
| Transfer list | Only approved, validated items go into grade A or B | Annex 1 para 4.12 |
| Surface sampling | At least monthly for Category 1 and 2 compounding. For Category 3: before a longer use date is assigned, and at least weekly | USP <797> 6.3.1 |
How the two types differ
China's pass box standard, JG/T 382-2012, classifies boxes by function: basic, purification, disinfection, negative pressure and airtight. Its purification type has a fan and high-efficiency filter that recirculates air inside the box. The listing excerpt does not use the words static or dynamic, so state the function you need in your URS.
| Feature | Static | Dynamic |
|---|---|---|
| Air supply | None | Fan and HEPA filter |
| Chamber air | Not flushed | Flushed with filtered air |
| Doors | Not open together | Not open together |
| Filter to test and replace | No | Yes |
How to choose
Start from the two rooms, not the box. Write the grade or class of each side, what passes through, how it is packed and how often.
Annex 1 para 8.47 expects items sterilised in sealed packaging to enter grade A by validated methods, such as airlocks or pass-through hatches, with the outside of the packaging disinfected.
Where an item enters a cleaner room and shedding is a risk, flushing is the option Annex 1 names. Where the transfer is between low-risk rooms and wiping is enough, your risk assessment may accept a static box. Write the reasoning down.
Annex 1 para 4.12 also says items meant for grade A should be protected while they pass through the grade B area.
Interlock timing and the approved list
Annex 1 para 4.13 says a time delay between closing and opening interlocked doors should be set where needed to keep areas segregated. If your process needs a delay, put its length in the data sheet.
Keep the approved transfer list with the box. Annex 1 para 4.12 says an unapproved item needs pre-approval as an exception, with a risk assessment and a disinfection and monitoring programme approved by quality assurance.
Sizing and servicing
Size the chamber to the largest item on the approved list, plus room to wipe it. A dynamic box also needs a power supply, and its filter needs integrity tests and changes in the maintenance plan.
Put these in the data sheet
State the function type, the chamber size, the door type and interlock, the filter grade for a dynamic box, the air speed and where it is measured, the surface finish and the sampling plan.
Who approves the room
Your regulator or customer auditor judges the facility. The contractor builds to your data sheet and supplies test results. The owner keeps the responsibility. 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.
Pass box with an airlock chamber: when a hatch is not enough
The glossary of EU GMP Annex 1 (25 August 2022) defines an airlock as an enclosed space with interlocked doors that keeps air pressure control between adjoining rooms. It calls a pass-through hatch synonymous with an airlock but typically smaller. The text gives no size at which a hatch becomes an airlock, so choose by the largest item on your approved list and how it is moved.
A static box has no fan or filter, so it does not flush its chamber the way para 4.12 asks of airlocks. If your risk assessment needs that flushing, a static box does not provide it.
| Point | What Annex 1 says | Paragraph |
|---|---|---|
| Personnel and materials | Airlocks for personnel should be separate from those for material wherever possible; where not practical, separate them in time by procedure | 4.12 |
| Air | Airlocks should be flushed effectively with filtered air so the grade of the cleanroom is maintained | 4.12 |
| Final stage | At rest, the final stage has the same grade as the cleanroom it leads to | 4.12 |
| Lower to higher grade | Moving material from a lower grade or unclassified area to a higher-grade area is cleaned and disinfected in proportion to the risk | 4.12 |
Questions
Common questions
What is the difference between a static and a dynamic pass box?
A static box has two doors that cannot open together and no air supply. A dynamic box adds a fan and HEPA filter that flush the chamber with filtered air.
Does GMP require a dynamic pass box?
Annex 1 para 4.12 gives flushing with an active filtered air supply as an example, not a rule. The owner's risk assessment decides.
Do pass box doors need interlocks?
Both doors must never open together. Annex 1 requires interlocks for airlocks leading to grade A and B. USP <797> says pass-through doors should be interlocking.
How often is a pass box sampled?
USP <797> asks for surface sampling at least monthly for Category 1 and 2 compounding. For Category 3 it asks for sampling before a longer use date is assigned, and at least weekly.
What air velocity should a dynamic pass box have?
The sources checked here give no pass box value. Annex 1's 0.36 to 0.54 m/s is a guidance value for unidirectional air at the working position (para 4.30), and for pass-through hatches it asks for effective flushing with filtered air (para 4.12). State the speed and the measuring point in your specification, then confirm them by test.
How much does a dynamic pass box cost?
This guide gives no figure, because price follows the specification. A dynamic box adds a fan, a filter and a controller to a static box, and chamber size, steel grade, door type and interlock also move the price. Compare offers on one data sheet and check whether test documents are included.
Related guides
- What a cleanroom costs to run: energy, filters and testing
- The Cleanroom Project Lifecycle
- Building a cleanroom inside an existing building
- Cleanroom cost per m²: published ranges by ISO class
- 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 1 November 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 1 November 2026
- GB 50073-2013, Code for design of clean room (issued 28 January 2013, in force 1 September 2013; term 2.0.22, pass box; checked 1 November 2026)
- JG/T 382-2012, Pass box (issued 16 May 2012, in force 1 November 2012; listing page with scope and classification; checked 1 November 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.
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