Buyers searching for a “cleanroom pass through” or comparing “static vs dynamic pass box” designs often encounter inconsistent terminology. Before requesting a quotation, it is important to define whether the transfer chamber simply isolates two rooms or actively recirculates HEPA-filtered air during the transfer interval.
This guide explains that industry split, identifies situations where a sealed static chamber may be sufficient, and outlines when buyers commonly ask for dynamic HEPA recirculation. It also maps the main transfer options in SENPEI’s pass boxes and transfer hatches range and provides a copy-ready enquiry checklist.
What buyers mean by static vs dynamic
A pass box, also written pass-through or pass-thru in US English, is a chamber installed through a wall or partition so items can move between rooms without using the main personnel doorway. Doors on opposite sides and an interlock help prevent both sides from being open at the same time.
A static pass box has no active supply airflow or fan-driven HEPA recirculation in the chamber. Its basic transfer control is the enclosed chamber, door seals, and interlock. Depending on the selected configuration, it may also include UV lighting, injection or validation ports, interior lighting, or another transfer-specific feature. These additions do not change its basic static-airflow classification.
A dynamic pass box adds a fan and HEPA filtration, commonly with unidirectional or laminar recirculation inside the chamber during the transfer dwell. The intent is to provide active airborne-particle control while items are inside the pass-through. A fan, filter arrangement, airflow pattern, operating sequence, and acceptance criteria all need to be defined for the intended process.
The static/dynamic distinction is therefore about airflow, not about whether the unit has UV, disinfection ports, stainless-steel construction, or an electronic interlock. A sealed unit with UV remains static unless it also has the specified fan-plus-HEPA recirculation system.
When static is enough
A static pass box is commonly considered for packed, wrapped, closed, or otherwise protected items where exposure inside the chamber is short and the transfer risk is controlled by the surrounding procedure. Typical reasons for selecting this simpler arrangement include:
- Items do not require active airborne-particle control during transfer.
- The main requirement is to avoid a directly open doorway between rooms.
- A two-door interlock and cleanable internal surfaces address the principal transfer risk.
- The facility already has validated cleaning, wrapping, and material-transfer procedures.
- There is no process requirement for fan-driven HEPA recirculation.
Even for a static unit, the enquiry should address more than chamber size. Confirm the wall construction and thickness, door arrangement, interlock type, clear opening, transferred-item dimensions, and any room differential-pressure or leakage-test criterion. A pass box must suit both the item and the wall interface.
Airtight pass boxes as a sealed static example
SENPEI’s airtight pass boxes use mechanically compressed doors with elastic seals and an electromagnetic interlock so both doors cannot open at once. The body is available in 304 or 316 stainless steel, with double tempered-glass windows. Options include a decontamination injection port, validation port, interior lighting, and UV lamp.
These features support a sealed-transfer arrangement; they do not make the unit dynamic. The product page does not publish a numeric leakage or pressure rating. If room pressure integrity matters, the buyer should state the required differential-pressure condition and leakage-test criterion for confirmation.
Likewise, optional ports, UV, or lighting alone do not establish a validated decontamination cycle or a biosafety rating. The buyer remains responsible for defining the process, cycle, and acceptance requirements.
Medical pass boxes as a static UV example
SENPEI’s medical pass boxes are wall-mounted units for transferring sterile items between rooms of different cleanliness classes. They use a two-door mechanical interlock and, in the page wording, a built-in 8 W UV germicidal lamp on all models. The casing can be powder-coated cold-rolled steel or stainless steel, with a brushed stainless-steel interior.
The page lists catalogue internal clear sizes of 500 × 500 × 500, 600 × 600 × 600, and 800 × 800 × 800 mm, with 220 V/50 Hz power. These are catalogue references only; dimensions, electrical requirements, configuration, availability, and supply scope must be confirmed on quotation.
There is no fan or HEPA-recirculation claim for this family. It is another static example, with UV as an additional feature rather than dynamic airflow.
When dynamic (laminar / HEPA recirculation) is justified
Buyers more often request dynamic HEPA recirculation when items are open, unwrapped, or otherwise exposed during transfer, or when the transfer crosses a larger cleanliness-class step. Higher-grade zone crossings and open-product transfers are common reasons to consider active particle control, including in pharmaceutical facilities developing contamination-control strategies.
A dynamic arrangement may be worth evaluating when:
- The transferred item or product contact surface is exposed inside the chamber.
- The process requires active HEPA-filtered airflow during a defined transfer interval.
- The cleanliness-class difference between the two rooms creates a higher airborne-contamination concern.
- The operating sequence needs a defined recirculation or dwell period before the receiving door can open.
- The qualification plan calls for agreed airflow and filtration acceptance checks.
Dynamic airflow should not be treated as an automatic substitute for cleaning, disinfection, wrapping, or a validated transfer procedure. HEPA recirculation addresses airborne particles; it does not by itself prove sterilization or surface decontamination. Buyers should define what the equipment is expected to achieve and how that performance will be checked at acceptance.
SENPEI confirms dynamic or laminar HEPA-recirculation configuration on quotation. There is no separate live product page for this option yet, so a generic industry parameter table should not be treated as a SENPEI specification. Describe the process and acceptance requirements in the enquiry rather than assuming a standard fan, airflow, noise, or filter configuration.
Other transfer options on this site
Not every transfer process is best served by either a conventional static chamber or a dynamic airflow box. SENPEI also lists options based on liquid disinfection or pulsed-light treatment.
Dunk tanks use a disinfectant basin to create a liquid disinfection barrier, with no shared airflow through the hatch. They include a mechanical compression interlock, 304 or 316 stainless-steel construction, a low-level alarm, and emergency stops on both sides. The buyer defines the disinfectant chemistry and follows the site procedure; compatible chemical classes listed on the page are examples, not a substitute for process validation.
Pulsed-light pass boxes use intense pulsed xenon ultraviolet during clean-to-non-clean transfer, with an optional combined cycle using atomized disinfectant spray and a standard two-door interlock. This is another treatment-based transfer option, not a HEPA or laminar-airflow claim.
An air shower is different again: it is a dry personnel or cargo entry cabin with HEPA jets, not a pass box. See the air shower sizing guide for that application.
Decision checklist
Work through the following questions before selecting a configuration:
- What is being transferred? Record whether items are packed, wrapped, closed, open, liquid, heat-sensitive, or otherwise process-sensitive.
- What is the cleanliness-class difference? Identify both rooms and whether the transfer crosses a higher-grade boundary.
- Is active airflow required? Choose static when enclosure and interlocking meet the process need; investigate dynamic HEPA recirculation when active particle control is required.
- What wall interface is involved? Confirm wall thickness, construction, opening, installation orientation, and door arrangement.
- Is differential pressure or leakage important? State the room condition and the required test criterion instead of assuming a sealed enclosure has a published rating.
- Which interlock is appropriate? Specify mechanical or electromagnetic operation and any required door-status or release logic.
- Is another treatment step needed? Consider UV, injection or validation ports, a liquid barrier, or pulsed light as separate process choices. Do not confuse any of these with dynamic airflow.
- What utilities are available? Confirm voltage, frequency, and other site requirements on quotation.
- How will acceptance be demonstrated? Define the relevant interlock, dimensional, leakage or pressure, treatment-cycle, and—if dynamic—airflow and HEPA checks before ordering.
Quote checklist
Copy and complete this block for the enquiry. Clear internal dimensions, item dimensions, wall details, and acceptance requirements will help distinguish a static sealed chamber from a dynamic or treatment-based configuration.
Transfer type: Static / dynamic HEPA recirculation / dunk tank / pulsed light / unsure
Process and transferred items:
Packed, wrapped, closed, or open:
Internal clear chamber size required (W × H × D, mm):
Maximum item size (W × H × D, mm):
Room cleanliness classes on both sides:
Wall thickness and construction:
Wall opening and door arrangement:
Room differential-pressure condition and leakage-test criterion, if required:
Material: 304 stainless steel / 316 stainless steel / other casing requirement
Interlock: Mechanical / electromagnetic / required operating sequence
Options: UV / injection port / validation port / lighting / liquid barrier / pulsed light
Power available:
Acceptance tests or documentation required:
Quantity:
Destination port:
Additional process requirements:Start with the SENPEI pass-box range to compare the live sealed-transfer, liquid-barrier, and pulsed-light families. For a static, dynamic, or other transfer configuration, send the completed checklist through request a quote so dimensions, wall interface, utilities, availability, and equipment supply scope can be confirmed.