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Key points of clean environment HVAC design
2026/5/25
1. Core Design Principles (3 major core aspects)
Cleanliness First: Based on the air cleanliness level (ISO 1-9 grades), the matching of filtration systems, air flow organization, and pressure difference control is carried out to completely prevent the spread of pollution.
Precise control: The humidity and temperature accuracy (such as ±0.5℃/±3% RH), pressure difference (10-30Pa), and air change frequency (10-100 times/h, depending on the cleanliness level) must be quantitatively met and achieved.
Energy-saving compatibility: Under the premise of meeting cleanliness requirements, optimize fresh air ratio, heat recovery, and variable frequency control to reduce operating energy consumption.
II. Key Design Modules (6 Core Aspects)
Air handling system design
Filter configuration: Primary efficiency (G3-G4) + Intermediate efficiency (F5-F8) + High efficiency (HEPA H13-H14) / Ultra-high efficiency (ULPA) three-level filtration. The high-efficiency filters should be placed close to the air supply end (such as FFU, air supply outlets). Processing functions: Includes temperature and humidity regulation, dehumidification / humidification (priority is isothermal humidification to avoid water mist pollution), sterilization (UV / antibacterial filtration, essential for biological scenarios). System form: Centralized: Large clean workshops (such as semiconductor factories), facilitating unified control; Semi-centralized: Laboratories / small clean areas, combined with FFU (fan-filter units) for flexible air supply.
2. Airflow distribution design (matched according to cleanliness level)
High cleanliness level (ISO 1-5): Vertical unidirectional flow ( laminar flow), air velocity 0.2 - 0.5 m/s, ensuring no vortex in the working area; Medium-low cleanliness level (ISO 6-9): Non-unidirectional flow (turbulent flow), top supply and bottom return / side return, optimizing the layout of supply air outlets to avoid dead corners; Special scenarios: Biosafety laboratories use negative pressure airflow to prevent harmful gases from leaking out.
3. Pressure Difference and Pressure Control
Pressure gradient: Clean area > Semi-clean area > Non-clean area. The pressure difference between adjacent areas should be ≥ 10 Pa. Control measures: Install pressure sensor + variable frequency fan. Adjust the air volume through the return air valve / exhaust air valve to maintain stable pressure. Fresh air supply design: Positive pressure area needs to reserve fresh air supply volume, negative pressure area needs to ensure smooth exhaust, to avoid excessive negative pressure that affects operation.
4. Temperature and Humidity Control and Energy Saving Design
Parameter settings: Electronics / Semiconductors: 22 ± 1℃, 45 ± 5% RH (anti-static, anti-condensation); Pharmaceuticals / Biology: 18 - 26℃, 30 - 60% RH (as per process requirements); Energy-saving measures: Fresh air heat recovery (sensible heat / total heat exchanger, recovering energy from exhaust air); Variable frequency control (fans, pumps adjust speed according to load); Zone control (independent regulation for different cleanliness levels areas to avoid energy waste).
5. Selection of ducts and materials
Material Requirements: The ducts should preferably be made of stainless steel (304/316L) or galvanized steel (with antibacterial coating) to avoid dust generation and accumulation; Construction Standards: The connections of the ducts should be tightly sealed (the flange gaskets should use non-fibrous materials), and after installation, they need to be cleaned and leak-tested (the air leakage rate should be ≤ 1%); Auxiliary Design: The insulation of the ducts should use non-combustible and non-toxic materials to prevent condensation pollution.
6. Supporting Facilities and Security Design
Fresh air guarantee: The fresh air volume must meet the maximum value of "person breathing + positive pressure supply + process exhaust volume", and the filtration must be up to standard; Exhaust air treatment: Harmful gases (such as laboratory waste gas, chemical dust) need to be purified (by activated carbon adsorption, high-efficiency filtration) before being discharged; Emergency system: A backup power supply (UPS) is set up to ensure the continuous operation of the clean area 24 hours a day (such as in semiconductor and pharmaceutical industries).
III. Design Process and Key Specifications
Initial input: Specify the cleanliness level, process requirements (ventilation volume, heat and moisture generation), and the number of personnel;
Core calculation: verification of heating and cooling loads, supply and return air volumes, fresh air volume, and filtration efficiency;
Reference standards: "Design Code for Cleanrooms" (GB 50073), "Technical Code for Construction of Biosafety Laboratories" (GB 50346), ISO 14644 series of standards.
IV. Core Summary
The key to the HVAC design of clean production environments lies in "matching technical solutions according to grades", focusing on filtration, airflow, and pressure difference, while also considering precise control and energy conservation. At the same time, it strictly adheres to industry standards to ensure that it meets the requirements of process production and safety.
If you need more detailed design points for specific scenarios (such as semiconductor factories, biological laboratories), please provide additional requirements.
