How to choose airtight transfer Windows?

When choosing airtight transfer Windows, multiple factors such as usage scenarios, performance parameters, functional configurations, material quality, and compliance need to be comprehensively considered. The following are specific selection points and suggestions:
First, clarify the usage scenarios and core requirements
1. Determine the cleanliness level of the application field
Biosafety Laboratory (BSL/ABSL): It is necessary to meet the requirements of high-level protection (such as BSL-3/4, ABSL-3/4), with particular attention paid to the air tightness test standards (such as negative pressure maintenance capacity, and leakage rate), disinfection functions (such as VHP vaporized hydrogen peroxide disinfection), and biosafety certifications (such as compliance with standards like NSF/ANSI 49 or GB 19489).
Pharmaceutical/food industry: It is necessary to comply with GMP, FDA, and other standards, emphasizing the corrosion resistance of materials (such as 316L stainless steel), self-cleaning ability (such as equipped with high-efficiency filters), and disinfection convenience (such as ultraviolet + ozone combination).
Electronic/semiconductor workshop: Focus on dust control. It is necessary to confirm the internal cleanliness level of the transfer window (such as ISO 5 level) and the airflow direction (such as unidirectional flow to prevent cross-contamination).
2. Evaluate the characteristics of the transferred items
Size and weight: Select the inner cavity size of the transfer window (such as length × width × height) based on the size of the items to ensure that large items can be smoothly placed. At the same time, pay attention to whether the height of the door opening is suitable for the trolley or pallet.
Sensitive requirements:
For items sensitive to ultraviolet rays (such as certain medicines and reagents): Avoid choosing single ultraviolet disinfection. VHP or moist heat disinfection should be preferred.
Items that need to be transferred quickly: Consider whether a rapid disinfection mode (such as short-term high-concentration VHP injection) or dual-door automatic control function is required.
Ii. Comparison of Key Performance Parameters
Air tightness index
Static leakage rate: It must comply with industry standards (for example, biosafety laboratories require a leakage rate of ≤0.5% vol/h, or a pressure difference attenuation of < 250Pa within 60 minutes), and the manufacturer can be requested to provide a third-party test report.
Dynamic sealing performance: Simulate actual usage scenarios (such as frequent door opening and closing), test the sealing performance under pressure difference fluctuations, and ensure no air leakage during long-term use.
2. Disinfection capacity
Disinfection method:
Ultraviolet (UV-C): Low cost, suitable for surface disinfection, but poor effect on shadow areas. It is necessary to confirm the lifespan of the lamp tube (usually 8000-12000 hours) and the radiation intensity (≥70μW/cm²).
VHP (vaporized hydrogen Peroxide): No residue, high sterilization efficiency (6-log kill rate), suitable for high-risk scenarios, but it is necessary to confirm the generator power, disinfection time (usually 30-60 minutes), and residual concentration control.
Ozone disinfection: It is suitable for space disinfection. It should be noted that residual odors need to be ventilated to disperse them. It is not suitable for items made of rubber, plastic, and other materials.
Disinfection verification: Request the manufacturer to provide a sterilization effect verification report (such as the results of the spore challenge test).
3. Cleanliness and self-cleaning function
Filter grade: High-efficiency filter (HEPA, filtration efficiency ≥99.97%@0.3μm) or ultra-high-efficiency filter (ULPA, filtration efficiency ≥99.9995%@0.12μm). The filtration efficiency and replacement cycle need to be confirmed.
Self-cleaning time: The time it takes for the air in the transfer window to reach the target cleanliness level after the fan is turned on (e.g., from a non-clean state to ISO 5 grade ≤10 minutes).
Iii. Structure and Material Selection
1. Box material
Stainless steel grade:
Common scenario: 304 stainless steel (corrosion-resistant and easy to clean).
Highly corrosive environments (such as frequent disinfection): 316L stainless steel (containing molybdenum, with stronger resistance to acid and alkali corrosion).
Surface treatment: The inner wall should be smooth without dead corners (such as arc corner design) to avoid dust accumulation. The welding area should be fully welded and polished to prevent the growth of microorganisms.
2. Sealing device
Sealing form:
Mechanical compression type: The sealing strip is pressed tightly by the door shaft spring or cylinder. It has a low cost but may cause leakage due to wear over long-term use.
Inflatable seal: It adopts an airbag seal, which forms a sealing band through air pressure expansion, providing more reliable sealing performance and is suitable for high-level protection scenarios (such as BSL-4 laboratories).
Sealing strip material: Select silicone rubber or ethylene propylene diene monomer (EPDM) rubber that is resistant to aging and chemical corrosion to avoid material hardening and cracking caused by long-term disinfection.
3. Door body and interlocking system
Door type: Swing door (suitable for small sizes) or sliding door (space-saving, suitable for large transfer Windows). It is necessary to confirm whether the resistance to opening and closing the door is moderate (such as ≤40N).
Interlock function: Electronic interlock must be available (manual unlocking can be done in case of malfunction) to prevent both doors from opening simultaneously. High-level scenarios can be equipped with dual protection of mechanical interlocking and electronic monitoring.
Iv. Functional Configuration and Intelligent Requirements
1. Basic functions
Differential pressure display: A differential pressure gauge is configured to monitor the pressure difference inside and outside the transfer window in real-time, facilitating the determination of the sealing status.
Lighting system: Built-in LED lights ensure sufficient internal light and facilitate the observation of items.
Residual sterilization monitoring (optional): For instance, VHP automatically detects the residual concentration of hydrogen peroxide after disinfection. Door opening is only allowed after meeting the standard.
2. Intelligent upgrade
Control system: Touchscreen operation interface, which can preset disinfection programs, record operation logs (such as disinfection time, number of door opening and closing times), and support data export.
Remote monitoring: Connect to the laboratory management system via the RS485 interface to monitor the status of the transfer window in real-time (such as door opening and closing, and fault alarms).
Automatic sensing: Infrared sensing for door opening and automatic triggering of disinfection programs reduce personnel contact and lower the risk of contamination.
V. Compliance and After-sales Service
Certification and Standards
Domestic scenarios: It is necessary to comply with GB 50346 "Technical Code for Construction of Biosafety Laboratories", GB 50457 "Design Standard for Clean Rooms in the Pharmaceutical Industry", etc.
Export scenarios: The European Union needs to comply with CE certification (such as EN 12469), and the United States needs to comply with NSF/ANSI 49 or ASHE standards.
Special scenarios: If the transfer of radioactive substances is involved, the thickness of the lead protective layer and the radioactive leakage detection report need to be confirmed separately.
2. Manufacturer qualifications and services
Give priority to choosing manufacturers with production qualifications for clean equipment and biosafety equipment test reports, and avoid using products from small workshops.
After-sales service: Confirm whether installation and commissioning, regular maintenance (such as filter replacement, sealing test), and emergency fault response (such as on-site repair within 24 hours) are provided.
Six. Balancing Budget and Cost-effectiveness
Cost structure: The price range of airtight transfer Windows is relatively wide (the ordinary type is about 10,000 to 30,000 yuan, and the high-grade biosafety type can reach 100,000 to 300,000 yuan). It is necessary to comprehensively consider the initial procurement cost and the long-term usage cost (such as disinfection consumables and filter replacement costs).
Suggestions for cost performance:
Low-risk scenarios: Prioritize meeting basic airtightness and disinfection functions, and choose an economical model (such as 304 stainless steel + ultraviolet disinfection).
High-risk scenarios: Regardless of the cost to ensure safety, choose imported brands or domestic first-line brands (such as Suzhou Sujing and Shanghai Runda), and equip with inflatable sealing + VHP disinfection + intelligent monitoring.
Summary: Selection decision-making process
Clear requirements: Scene level (such as BSL-3), item characteristics (size, sensitivity), disinfection requirements (sterilization efficiency, residue limit).
Screening parameters: Narrow down the brand range based on core indicators such as air tightness, disinfection method, and material grade.
On-site inspection: Visit the manufacturer's production line and check the actual operation effect of similar cases (such as the actual measurement of door sealing gaps and disinfection time).
The contract stipulates that the testing standards (such as leakage rate testing methods), acceptance procedures (such as third-party testing reports), and warranty period shall be specified in the procurement contract.
Through the above steps, it can be ensured that the selected airtight transfer window not only meets the functional requirements but also complies with regulatory standards, minimizing the risk of cross-contamination to the greatest extent.