Cleanroom Dynamic Pass Box (DPB) — Active HEPA Filtration Gateway Between Classified & Non-Classified Areas
A Dynamic Pass Box is a self-contained structural unit installed between classified and non-classified areas, operating with vertically HEPA-filtered airflow to maintain cleanliness and minimise contamination during material transfer. Unlike a static pass box which relies on a pressure differential alone, the Dynamic Pass Box actively creates a Grade A (Class 100) environment within its chamber — scrubbing the surface of every item transferred with clean air before the inner door is opened.
Pass Box — The Controlled Transfer Gateway Between Sterile Zones
A pass box is one of the fundamental cleanroom systems used to transfer materials from one area to another through a controlled environment, in order to prevent airborne cross-contamination. The primary function of a pass box is to transfer material safely without raising contamination concerns — any particulate matter present on the material surface is minimised during the transfer operation before the material crosses the zone boundary.
📌 The Interlocking Door Mechanism — The Core Safety Feature
The interlocking door mechanism is the key contamination-prevention feature of a pass box. When the door on one side is open, the opposite-side door remains locked — ensuring that the two rooms connected by the pass box are never simultaneously open to a common air channel. This mechanical or electromagnetic rule prevents the pressure differential between the two rooms from being breached at any point during the transfer event, maintaining the ISO class integrity of both zones throughout material handling operations.
Pass boxes are also widely known as cleanroom pass-throughs, clean transfer windows, and transfer hatches. They are used in microbiology laboratories, pharmaceutical manufacturing, food processing, chemical industries, and all cleanroom environments where material must move between zones of different cleanliness classification or where zone air must be protected from mixing during transfer.
Active HEPA filtration — Class-crossing transfers
Pressure integrity — Same-class transfers
How the Dynamic Pass Box Actively Creates a Grade A Environment at Every Transfer
The core engineering distinction between a dynamic and static pass box is that the dynamic unit does not rely on the ambient cleanroom environment to maintain cleanliness during transfer — it generates its own Grade A environment actively, independent of the surrounding rooms.
Recirculatory Airflow — The Grade A Self-Generating System
The motor-blower (mounted with a suspension arrangement to prevent vibration transmission to the cabinet body) draws air from the pass box chamber interior through floor-level return grilles, passes it through the G4 pre-filter (which captures particles above 5 micron — protecting the H14 HEPA membrane from early loading by coarser particles), then forces it through the H14 HEPA filter which removes 99.97% of particles at 0.3 micron MPPS, and delivers it back into the chamber in a downward vertical pattern. This closed-loop recirculatory system continuously improves the air quality in the chamber throughout the transfer cycle — the particle count in the chamber falls toward Grade A (ISO Class 5) within minutes of the outer door being closed and the blower being activated, as each recirculation pass removes particles from the chamber air until the population falls below the Grade A threshold. The G4 pre-filter in the return path is replaceable without removing the H14 HEPA filter, allowing the HEPA filter to maintain its rated filtration efficiency throughout its full service life rather than being loaded prematurely by coarse particles.
Electromagnetic Interlocking — Sequential Access with Fail-Safe Logic
The electromagnetic door interlocking system of the dynamic pass box uses a logic controller PCB that monitors the status of both doors and enforces the sequential access rule: only one door can be open at any time. When Door A (dirty/non-classified side) is opened, the PCB activates the electromagnetic lock on Door B (clean/classified side) and prevents it from being unlocked until Door A is closed and latched. The reverse applies when Door B is opened. The LED status indicators (Red = locked, Green = available) mounted on both door frames communicate the current interlock state to personnel on both sides of the pass box, preventing the common error of attempting to force a locked door. The interlock logic controller is powered from a dedicated circuit with a battery-backed UPS — in the event of a power failure, the UPS maintains the electromagnetic lock power supply for a minimum of 4 hours, ensuring that both doors remain locked and the cleanroom pressure gradient is maintained through a power outage. Fail-safe mode: power loss to the main PCB results in both electromagnetic locks engaging, not releasing — the pass box defaults to the most secure state on any electrical fault.
UV-C Germicidal Lamp — Automated Surface Sterilisation
The UV-C germicidal lamp is activated during the idle period between transfer cycles — when both doors are closed and interlocked. The lamp activates automatically after a programmed delay following the closing of the last-opened door (typically 5–10 minutes, set via the control panel), runs for the programmed cycle time (typically 15–60 minutes for standard pharmaceutical applications), and then deactivates automatically and initiates a blower purge cycle that clears any ozone generated by the UV-C lamp before the next transfer cycle. The lamp is interlocked with both doors — it cannot be activated when either door is open, and both doors are locked during UV-C operation to prevent personnel exposure to UV-C radiation. An optional UV-C lamp hour meter tracks cumulative lamp operating hours, allowing planned lamp replacement before the germicidal output falls below the effective threshold. The optional UV intensity sensor measures the actual UV-C output reaching the chamber surfaces and alerts the operator when the measured intensity falls below 70% of the lamp rated output.
Magnehelic Gauge — Continuous Filter Health Monitoring
The magnehelic gauge (differential pressure gauge) is mounted on the front face of the pass box control panel and measures the pressure differential across the H14 HEPA filter — the difference between the static pressure upstream of the filter (blower discharge) and the static pressure downstream of the filter (chamber supply). A clean HEPA filter has a low pressure differential (typically 15–25 Pa at the operating airflow rate); as the filter loads with captured particles over its service life, the pressure differential increases (typically to 80–100 Pa at end-of-life). The magnehelic gauge provides a continuously visible indication of filter loading status — visible on the pass box front panel without opening any service door — allowing cleaning and maintenance personnel to monitor filter health during each transfer cycle. An optional differential pressure switch (connected to the control panel LED alarm circuit) provides an automatic visual alarm when the filter pressure differential exceeds the set replacement threshold, ensuring that the filter is replaced before its loading reduces the effective airflow velocity and HEPA filtration efficiency below the Grade A maintenance threshold.
Eight Engineering Features of the Metrolabs Dynamic Pass Box
Every Metrolabs Dynamic Pass Box is built to these engineering standards — making it a self-contained cleanroom environment, not a hatch with a blower:
H14 HEPA Filter System — 99.97% Filtration Efficiency
The H14 HEPA filter (rated to EN 1822 — 99.97% minimum filtration efficiency at the 0.3 micron MPPS) is installed in the canopy of the pass box in a gel-seal or knife-edge frame that prevents any unfiltered air from bypassing the filter perimeter. Only air that has passed through the HEPA membrane enters the chamber interior. Combined with the G4 pre-filter on the recirculation return, the system maintains Grade A air quality in the chamber throughout the transfer cycle, with a particle count continuously driven toward the ISO Class 5 threshold with each recirculation pass.
Motor-Blower with Suspension Arrangement — Low Noise Operation
The centrifugal or EC motor blower is mounted in the canopy above the HEPA filter with a vibration isolation suspension arrangement — rubber anti-vibration mounts at each blower mounting point that decouple the blower vibration from the cabinet structure. This prevents the blower’s operating vibration from being transmitted through the cabinet body to the cleanroom wall panel, eliminating the resonant vibration and noise that unsilenced blowers in standard pass boxes create. The blower speed is selected to achieve the required face velocity at the HEPA filter (typically 0.45 m/s – 0.9 m/s for Grade A) with the minimum noise level achievable at that velocity. The blower on/off switch is on the control panel, with a time delay relay that keeps the blower running for a brief purge cycle after the UV-C cycle completes.
Electromagnetic Interlocking Doors — Fail-Safe Logic Controller
Heavy-duty electromagnetic locks on both doors — connected to a logic PCB that enforces one-door-open-at-a-time. Both doors are SS 316L-framed with double-glazed toughened safety glass vision panels — flush-mounted to the door frame (zero-ledge, no recessed frame that collects dust). SS 316L handles and SS 304 or SS 316L hinges. The door gaskets are medical-grade silicone — compressible to an airtight seal at the door perimeter on closing. The PCB is powered from a battery-backed UPS — power loss defaults to both locks engaged. Status LED lights (Red/Green) are mounted on both door panels, flush with the frame surface.
UV-C Germicidal Lamp — Programmable Auto-Cycle
Mounted in the upper interior corners of the chamber — 360° irradiation coverage of all interior surfaces and of transferred item surfaces. Door-interlocked: UV-C cannot activate when either door is open. Programmable cycle timer on the control panel (factory default 30 minutes — adjustable 15–60 minutes). Auto purge cycle after lamp deactivation to clear ozone before next transfer. Standard LED type or traditional UV-C tube depending on application. Optional UV-C hour meter for planned replacement scheduling.
SS 304 / 316L Stainless Steel Construction — Rugged & Durable
The interior chamber is SS 304 (standard) or SS 316L (optional) — with all internal corners coved to a large radius to prevent particle and moisture accumulation. The internal surface is brushed or mirror-polished to Ra <0.8μm (standard) or Ra <0.5μm (SS 316L EP optional). The exterior body is brushed SS 304 — matching the cleanroom panel aesthetic. All internal welds are ground flush and polished. The construction is rugged and durable — the pass box is engineered for long-term performance under repeated daily transfer cycles, frequent IPA wipe-downs, and periodic VHP decontamination cycles throughout the cleanroom service life.
LED Tube Light Illumination — Full Visibility During Loading
LED tube light illumination inside the pass box chamber provides full visibility during the loading and unloading operations — personnel on both the dirty and clean side can see the items in the chamber clearly through the double-glazed glass door panels, confirm item identity and position before closing their side door, and verify that the chamber is fully empty before the next transfer cycle begins. The LED fitting is flush-mounted in the chamber ceiling — no protruding fixture, no shadow zones, and no conventional lamp that generates heat inside the chamber that could affect temperature-sensitive pharmaceutical products.
Flush Mounting — Zero-Ledge Seamless Wall Integration
The Metrolabs Dynamic Pass Box is designed to be installed flush with the cleanroom panel wall surface on both sides — the door frames are specified to the thickness of the cleanroom panel so that the pass box face is flush with the panel face on both the classified and non-classified sides. No external dust-collecting ledge, no recessed face that creates a step in the panel surface, and no exposed structural frame members that create obstacles to wall cleaning. The panel-to-pass-box junction is sealed with pharmaceutical-grade silicone on both sides — forming a cleanable, continuous seal between the panel surface and the pass box frame throughout the cleanroom service life.
Easy to Operate & Maintain — Audit-Ready Documentation
The dynamic pass box is designed for daily operation by non-specialist cleanroom personnel — the operating procedure is load items (dirty side), close dirty-side door, wait for Grade A confirmation (blower + particle count interval), open clean-side door, unload. All controls are on the front panel: blower on/off, UV-C on/off, LED status. Filter replacement, UV-C lamp replacement, and blower maintenance are all front-access — no special tools and no cleanroom shutdown required. Factory PAO/DOP test performed before dispatch to confirm HEPA filter integrity. Test certificates and calibration certificates supplied for direct inclusion in GMP audit and ISO qualification documentation.
Dynamic Pass Box — Standard Technical Specification
Metrolabs Dynamic Pass Box standard specification — customisable at any parameter to meet your facility requirement:
| Specification | Details |
|---|---|
| Design Type | Dynamic — Active HEPA Filtration |
| Cleanliness Level✓ Grade A | Class 100 / ISO Class 5 |
| Standard Internal Dimension | 2×2×2 Ft (60×60×60 cm) |
| Custom Sizes | Available as per customer requirements |
| MOC (Standard) | Stainless Steel 304 |
| Illumination | LED Tube Light — flush-mounted |
| Air System | Motor-Blower with Suspension Arrangement |
| Pre-Filter | G4 — 95% efficiency down to 5 micron |
| HEPA Filter | H14 — 99.97% — protected by SS grills |
| Door System | Two-side doors · Glass window · SS handles & SS hinges · Electromagnetic interlocking |
| Standard Fittings | UV light · Door status LED indicators · On/off switch for blower |
| Power Supply | 220 Volts / 50 Hz |
Configure Your Dynamic Pass Box — Optional Upgrades & Accessories
Every Metrolabs Dynamic Pass Box can be configured with optional accessories to match your specific facility requirements, GMP documentation needs, and ISO class:
SS 316 / SS 316L MOC
Upgrade from standard SS 304 to SS 316 or SS 316L for VHP-intensive environments and Grade A/B pharmaceutical suites. Provides superior pitting corrosion resistance against chloride-containing disinfectants.
Differential Pressure Gauge
Magnehelic ΔP gauge mounted on front control panel — monitors HEPA filter loading continuously. Visual replacement indicator when pressure differential exceeds the end-of-life threshold.
DOP Test Port
Dedicated upstream and downstream sampling ports for PAO (Poly-Alpha Olefin) or DOP test during filter integrity commissioning and routine qualification, required for ISO and GMP audit compliance.
Flange for Panel Mounting
Structural flange at the perimeter of the pass box body for secure bolting to the modular cleanroom panel structural frame — ensures flush, airtight panel-to-pass-box mounting without silicone-only sealing.
Test Certificates (PAO/DOP)
Factory-performed PAO or DOP HEPA filter integrity test with full test report — confirms filter installation integrity and measured filtration efficiency before dispatch. Required for GMP IQ documentation.
Calibration Certificate
Calibration certificate for the magnehelic ΔP gauge and any instrumentation fitted to the pass box — traceable to national standards. Required for GMP instrument qualification documentation.
Door Buzzer Alarm
Audible door-open alarm — activated when a door remains open beyond the configured time (factory default 30 seconds). Alerts personnel on both sides of the pass box to an incomplete transfer procedure.
UV-C Light Hour Meter
Cumulative UV-C lamp operating hour counter — mounted on the control panel. Enables planned lamp replacement at the manufacturer’s recommended life (typically 8,000–10,000 hours) before germicidal output falls below effective threshold.
Dynamic Pass Boxes Across Every ISO Class and Regulated Sector
H14 HEPA Grade A active filtration for every cleanroom where materials cross classification boundaries:
Pharmaceutical GMP
Dynamic pass boxes for Grade C-to-Grade B material entry. H14 HEPA Grade A active scrubbing of item surfaces. EM interlock fail-safe. EU Annex 1 (2022) compliant. Full GMP IQ documentation including PAO test record at handover.
Aseptic Manufacturing
Dynamic pass boxes for vial, ampoule, stopper, and closure component entry into aseptic Grade A/B suites. UV-C idle-period germicidal cycle. Grade A chamber confirmation before clean-side door release.
Biotech & ATMP
Dynamic pass boxes for cell culture media, reagents, and single-use component transfer into ATMP and cell therapy GMP suites. VHP-compatible SS 316L option for high-frequency room decontamination.
Semiconductor Fabs
Dynamic pass boxes for wafer cassette and process component transfer across ISO class boundaries in semiconductor manufacturing cleanrooms. ESD-safe interior specification available on request.
Hospital & CSSD
Dynamic pass boxes for sterile-to-non-sterile zone material transfer in hospital pharmacy cleanrooms, CSSD, and oncology drug preparation suites. NABH compliant with full documentation package.
BSL Containment
Dual-HEPA Dynamic Pass Boxes (H14 on both supply and exhaust paths) for BSL-2 and BSL-3 containment material transfer — preventing any hazardous agent from escaping the containment zone during material handling.
Microbiology Labs
Dynamic pass boxes for sample and reagent transfer into Class II Biosafety Cabinets and microbiological testing areas. UV-C germicidal idle disinfection. EM interlock. Standard 2×2×2 Ft or custom dimensions.
Food & Beverage
Dynamic pass boxes for high-care food production zone material entry — packaging component transfer, ingredient entry, and sample removal from high-care zones. FSSAI high-care zone compliance with active HEPA filtration.
Long-Term Performance, Zero-Ledge Design & Audit-Ready Documentation
Metrolabs focuses on long-term performance and Zero-Ledge engineering — every pass box is designed to be a seamless extension of the modular cleanroom panel system, not an industrial unit inserted into a cleanroom wall:
Zero-Ledge Flush Mounting — No External Dust-Collecting Protrusions
Every Metrolabs Dynamic Pass Box is designed to be installed level with the cleanroom panel wall surface — the door frame is flush with the panel face on both sides, no external dust-collecting ledges exist on the cleanroom side of the panel, and the pass box-to-panel junction is sealed with pharmaceutical-grade silicone. This design eliminates the most common contamination audit finding associated with pass boxes — the ledge at the top of the pass box frame where dust accumulates between cleaning cycles.
Silent Operation — Optimised Aerodynamics, Vibration-Isolated Blower
Optimised internal aerodynamics — the blower inlet and HEPA filter plenum are designed to maintain laminar air entry into the blower at all operating speeds, minimising aerodynamic noise from turbulence at the inlet. Combined with the vibration-isolation suspension mounting, the pass box operates with minimal noise contribution to the cleanroom environment — ensuring that the hygiene stations adjacent to the pass box can be used without disturbance from pass box blower noise.
Audit-Ready Documentation — Factory-Validated for ISO & GMP
Every Metrolabs Dynamic Pass Box is factory-validated for airflow velocity (measured at the HEPA filter face and at the door opening) and filter integrity (PAO/DOP test confirming no bypass around the filter perimeter) before dispatch. The factory test report, material test certificates (MTCs), ASTM A967 passivation certificate, and calibration certificates (if applicable) are supplied at handover as part of the IQ documentation package — structured for direct inclusion in ISO qualification and GMP audit submissions.
Pressure Gradient Management — Higher Internal Pressure for Clean Sweep
The Metrolabs Dynamic Pass Box maintains a higher internal pressure than the surrounding rooms — ensuring a constant outward clean sweep when doors are accessed. The motor-blower is set to deliver a chamber pressure typically 5–15 Pa above both the classified and non-classified room pressures — so when either door is opened, the air flow is always outward from the clean chamber into the room, never inward from the room into the clean chamber. This prevents any room-air ingress during the door-open period of the transfer cycle.
Dynamic Pass Box vs Static Pass Box vs Standard Hatch
Dynamic vs Static: Use a dynamic pass box when materials are crossing from a lower to a higher ISO class (e.g. non-classified to Grade B, or Grade C to Grade A). Use a static pass box for transfers between two rooms of the same ISO class where the goal is pressure integrity rather than active decontamination. See Static Pass Box →
From Specification to Factory-Tested & IQ-Documented Dynamic Pass Box
Metrolabs manages the complete pass box supply and commissioning process:
Specification & Design
ISO classes of both rooms confirmed. Transfer material type assessed. MOC (SS 304 / SS 316L), internal dimensions (standard 2×2×2 Ft or custom), optional features (magnehelic gauge / DOP port / flange / touchscreen HMI / dual-HEPA), power supply, and mounting configuration confirmed. Dimensioned drawing produced and signed off.
Fabrication
Interior chamber fabricated — SS 304 or SS 316L — coved corners. HEPA canopy and blower housing fabricated. Blower installed with vibration mounts. HEPA H14 filter installed with gel-seal frame. G4 pre-filter fitted. EM interlock PCB installed and tested. UV-C lamp mounted and interlocked. LED illumination fitted. SS hinges, handles, and door gaskets fitted. Polished and passivated. MTCs issued.
Factory Test & Validation
Airflow velocity measured at HEPA filter face and door opening. PAO/DOP integrity test performed on HEPA filter — confirms no bypass. EM interlock function tested (both door sequences). UV-C interlock tested. LED indicators tested. Full transfer cycle simulated. Test report produced. Optional: calibration certificate for magnehelic gauge.
IQ Documentation
SS MTCs, ASTM A967 passivation cert, H14 EN 1822 filter cert, PAO/DOP test report, airflow velocity measurement record, EM interlock test record, UV-C interlock test record, and installation photos compiled for GMP IQ qualification submission at handover.
Factory & Office
4, SIDCO-MICRO, Thirumudivakkam,
Chennai – 600 132, Tamil Nadu
🗺 Open in Google Maps ↗
Phone
Website & GSTN
www.metrolabs.biz
www.schoollabfurniture.com
GSTN: 33AASFM3382K1ZT
Ready to Install a Dynamic Pass Box in Your Cleanroom?
Contact Metrolabs for a free consultation. Our specialists will confirm your ISO class requirements, transfer material type, internal dimensions, optional features, and documentation requirements — then fabricate, factory-test, and supply your Dynamic Pass Box with complete IQ documentation at delivery.
🔌 Request a Free Dynamic Pass Box Quote
Quote Request Received!
Our pass box team will contact you within 24 working hours.
Immediate: 9840931231