Frequently Asked Questions About Pass Boxes

Q1. What is the difference between a static and a dynamic pass box?

A static pass box relies entirely on the facility’s pressure differential to prevent contamination — it has no active air handling. A dynamic pass box incorporates an internal HEPA fan-filter unit that actively creates laminar airflow inside the chamber, purging particles from transferred items and achieving ISO Class 5 conditions. For pharmaceutical GMP and high-grade cleanrooms (ISO Class 5–7), a dynamic pass box is typically mandated. For lower-grade areas (ISO Class 7–8) or less sensitive transfers, a static pass box is sufficient and more cost-effective.

Q2. What materials are Cronax pass boxes made from?

The standard construction uses AISI 304 stainless steel for the body and all internal surfaces, with a mirror-polished interior (Ra ≤ 0.4 µm) and satin or mirror exterior finish. For highly corrosive environments or pharmaceutical API applications requiring enhanced chemical resistance, we offer SS 316 / 316L as standard material. Mild steel with epoxy powder coating is available for non-pharmaceutical, budget-constrained applications.

Q3. Can both doors of a pass box be opened at the same time?

No — by design. The interlock system (mechanical or electro-mechanical) ensures that only one door can be opened at any given time. This is the defining safety and contamination-prevention feature of a pass box. If one door is open, the opposing door’s latch is physically or electrically disabled. Both Cronax mechanical and electro-mechanical interlocks are fail-safe: a power failure defaults to the secure (interlocked) state.

Q4. How often do HEPA filters in a dynamic pass box need replacement?

Under normal operating conditions, H14 HEPA filters in Cronax dynamic pass boxes have a typical service life of 12–24 months. The actual replacement interval depends on the particulate load of the incoming air, usage frequency, and whether pre-filters are installed. We recommend filter integrity testing (DOP/PAO challenge test) every 6 months as part of routine qualification maintenance. Cronax supplies OEM replacement filters and provides AMC support.

Q5. What cleanroom class is achieved inside a Cronax dynamic pass box?

Cronax dynamic pass boxes with H14 HEPA filtration achieve ISO Class 5 (Federal Standard 209E: Class 100) conditions inside the chamber during the laminar flow cycle, measured at ≥0.5 µm particle size. This is verified by particle count testing per ISO 14644-1 and is documented in our factory test report supplied with every unit.

Q6. Do you provide IQ/OQ documentation for pharmaceutical clients?

Yes. Cronax provides a comprehensive qualification document package including:

• Factory Acceptance Test (FAT) report
• Installation Qualification (IQ) protocol and report template
• Operational Qualification (OQ) protocol and report template
• HEPA filter integrity test certificate (PAO challenge)
• Calibration certificates for measuring instruments used
• User manual and maintenance schedule

These documents are formatted to support regulatory submissions to CDSCO, WHO-GMP inspectors, USFDA, MHRA, and other global regulatory bodies.

Q7. What wall thickness can Cronax pass boxes be installed in?

Standard Cronax pass boxes accommodate wall thicknesses between 100 mm and 350 mm. For thicker walls or special installations (double-wall sandwich panel systems, glass-reinforced plastic cleanroom panels), we manufacture custom extension frames. Provide your wall construction details during enquiry and our team will engineer the correct mounting solution.

Q8. Can the pass box size be customised for large components?

Absolutely. Customisation is a core capability at Cronax. We engineer pass boxes to accommodate items ranging from small vials and petri dishes to large trays, drums, and equipment components. Provide your largest transfer item’s dimensions and our engineers will design the optimal internal chamber size, ensuring the item can be transferred with clearance and that the HEPA airflow pattern (in dynamic units) covers the load effectively.

Q9. Is an electrical connection required for a static pass box?

Not necessarily. Static pass boxes with purely mechanical interlocks require no electrical connection and are fully operational in any facility, including areas with no convenient power outlet nearby. If you require LED status indicators or an electro-mechanical interlock, a 220V AC connection is needed. Dynamic pass boxes always require a power connection for the HEPA fan motor.

Q10. What is the typical delivery time for a Cronax pass box?

Standard catalogue models are delivered within 2–3 weeks of order confirmation and advance payment. Fully customised units — special dimensions, special materials, PLC controls, or RTP ports — are delivered in 4–6 weeks. Urgent requirements can be discussed on a case-by-case basis. Contact our sales team for project-specific timelines.

Q11. Do you export pass boxes internationally?

Yes. Cronax Industries exports pass boxes to customers in the UAE, Saudi Arabia, Bangladesh, Sri Lanka, Kenya, Tanzania, Nigeria, and Southeast Asian markets. We manage export documentation, pre-shipment inspection, and can provide CE marking documentation for European market customers on request.

Q12. How do I determine the right size pass box for my application?

The determining factors are: (a) the largest item you will transfer, (b) your wall construction and available cutout dimensions, and (c) the cleanroom classification on both sides of the wall. Contact Cronax with these three pieces of information and we will recommend the right model. We also offer free facility assessments for large projects.