Stainless steel cleanroom doors represent a critical architectural component in controlled environments where contamination control, hygiene maintenance, and environmental separation are paramount. These specialized barrier systems serve as the primary interface between classified cleanroom spaces and adjacent areas, functioning not merely as physical barriers but as engineered systems that maintain differential pressure, prevent particulate infiltration, and withstand rigorous decontamination protocols.
In pharmaceutical manufacturing, biotechnology research, semiconductor fabrication, and healthcare facilities, the integrity of cleanroom doors directly impacts product quality, research validity, and patient safety. Unlike conventional architectural doors, cleanroom doors must satisfy stringent requirements defined by international standards including ISO 14644 (Cleanroom and Associated Controlled Environments), EU GMP Annex 1 (Manufacture of Sterile Medicinal Products), FDA 21 CFR Part 211 (Current Good Manufacturing Practice for Finished Pharmaceuticals), and WHO Technical Report Series guidelines for pharmaceutical production facilities.
The selection of stainless steel as the primary construction material reflects specific engineering requirements: corrosion resistance to aggressive cleaning agents, non-porous surfaces that prevent microbial colonization, dimensional stability under thermal cycling, and compatibility with various sterilization methods including vaporized hydrogen peroxide (VHP), ultraviolet germicidal irradiation (UVGI), and chemical disinfectants. This article examines the technical design considerations, material specifications, performance requirements, and selection criteria for stainless steel cleanroom doors in regulated environments.
The selection of stainless steel grade for cleanroom door construction involves balancing corrosion resistance, mechanical properties, cost considerations, and regulatory compliance. The two primary grades used in cleanroom applications are austenitic stainless steels: AISI 304 (UNS S30400) and AISI 316L (UNS S31603).
AISI 304 Stainless Steel contains approximately 18% chromium and 8% nickel, providing excellent corrosion resistance in most cleanroom environments. The chromium content forms a passive chromium oxide layer (Cr₂O₃) on the surface, which self-repairs in the presence of oxygen and prevents further oxidation. This grade offers adequate resistance to:
AISI 316L Stainless Steel incorporates 2-3% molybdenum in addition to chromium and nickel, significantly enhancing resistance to chloride-induced pitting and crevice corrosion. The "L" designation indicates low carbon content (<0.03%), which prevents sensitization and intergranular corrosion during welding. This grade is specified for:
| Property | AISI 304 | AISI 316L | Test Standard |
|---|---|---|---|
| Chromium Content | 18.0-20.0% | 16.0-18.0% | ASTM A240 |
| Nickel Content | 8.0-10.5% | 10.0-14.0% | ASTM A240 |
| Molybdenum Content | - | 2.0-3.0% | ASTM A240 |
| Carbon Content (max) | 0.08% | 0.03% | ASTM A240 |
| Tensile Strength | 515 MPa (min) | 485 MPa (min) | ASTM A370 |
| Yield Strength | 205 MPa (min) | 170 MPa (min) | ASTM A370 |
| Elongation | 40% (min) | 40% (min) | ASTM A370 |
| Pitting Resistance (PREN) | 18-20 | 24-26 | ASTM G48 |
| Hardness (Rockwell B) | 70-90 HRB | 70-95 HRB | ASTM E18 |
Surface finish directly impacts cleanability, particle generation, and microbial adhesion. The surface roughness average (Ra) must be specified according to cleanroom classification and application requirements.
Standard Surface Finishes for Cleanroom Doors:
| Finish Designation | Ra Value (μm) | Ra Value (μin) | Description | Application |
|---|---|---|---|---|
| 2B (Mill Finish) | 0.4-1.0 | 16-40 | Cold rolled, heat treated, pickled | ISO Class 8-9, general cleanrooms |
| 2R (Bright Annealed) | 0.2-0.5 | 8-20 | Bright cold rolled finish | ISO Class 7-8, pharmaceutical areas |
| BA (Bright Annealed) | 0.1-0.3 | 4-12 | Highly reflective, smooth | ISO Class 6-7, aseptic processing |
| Electropolished | 0.05-0.15 | 2-6 | Electrochemical surface removal | ISO Class 5-6, sterile manufacturing |
| Mechanical Polish #4 | 0.4-0.8 | 16-32 | Directional satin finish | ISO Class 7-8, food processing |
According to ASME BPE (Bioprocessing Equipment) standards, surfaces in direct product contact areas should achieve Ra ≤ 0.8 μm (32 μin), while non-product contact surfaces in classified areas should maintain Ra ≤ 1.6 μm (63 μin). Electropolished surfaces reduce surface area by 20-30%, decreasing particle entrapment sites and facilitating more effective cleaning validation.
Material thickness directly affects door rigidity, impact resistance, sound attenuation, and thermal performance. Insufficient thickness leads to panel deflection, seal compression failure, and acoustic transmission.
Recommended Thickness Specifications:
| Component | Standard Thickness | Heavy-Duty Thickness | Material Grade | Justification |
|---|---|---|---|---|
| Door Frame | 1.2 mm (18 gauge) | 1.5 mm (16 gauge) | 304/316L | Structural support, hinge mounting |
| Door Panel (Exterior) | 1.0 mm (20 gauge) | 1.2 mm (18 gauge) | 304/316L | Impact resistance, rigidity |
| Door Panel (Interior) | 0.8 mm (22 gauge) | 1.0 mm (20 gauge) | 304/316L | Weight optimization, cost balance |
| Reinforcement Plates | 2.0 mm (14 gauge) | 3.0 mm (11 gauge) | 304 | Lock/hardware mounting areas |
| Threshold | 3.0 mm (11 gauge) | 4.0 mm (8 gauge) | 304 | Traffic wear resistance |
Frame thickness of 1.2 mm provides adequate rigidity for doors up to 1200 mm width × 2400 mm height. Wider doors (>1200 mm) or doors subject to high-traffic conditions require 1.5 mm frames to prevent deflection and maintain seal compression. The relationship between thickness and deflection follows the equation:
δ = (F × L³) / (48 × E × I)
Where:
- δ = maximum deflection
- F = applied force
- L = span length
- E = elastic modulus (193 GPa for stainless steel)
- I = moment of inertia (proportional to thickness³)
This cubic relationship demonstrates that increasing thickness from 1.0 mm to 1.5 mm reduces deflection by approximately 70%, significantly improving long-term seal integrity.
The door core provides structural rigidity, thermal insulation, acoustic attenuation, and fire resistance. Three primary core materials are used in cleanroom door construction, each offering distinct performance characteristics.
Honeycomb Core Structures:
Paper honeycomb cores consist of kraft paper formed into hexagonal cells, typically with cell sizes ranging from 6 mm to 19 mm. The hexagonal geometry provides optimal strength-to-weight ratio, with the structure resisting compression perpendicular to the cell axis while allowing flexibility parallel to the cells.
Aluminum honeycomb cores offer superior strength and moisture resistance compared to paper cores. The aluminum alloy (typically 3003-H19) provides enhanced fire resistance and dimensional stability in high-humidity environments.
Core Material Comparison:
| Core Material | Density (kg/m³) | Compressive Strength (MPa) | Thermal Conductivity (W/m·K) | Fire Rating | Cost Index |
|---|---|---|---|---|---|
| Paper Honeycomb | 48-96 | 1.5-3.5 | 0.045-0.065 | Class B (ASTM E84) | 1.0 |
| Aluminum Honeycomb | 80-160 | 3.0-8.0 | 0.080-0.120 | Class A (ASTM E84) | 2.5-3.0 |
| Mineral Wool | 100-150 | 0.3-0.8 | 0.035-0.042 | Class A (ASTM E84) | 1.8-2.2 |
| Polyurethane Foam | 40-60 | 0.2-0.5 | 0.022-0.028 | Class C (ASTM E84) | 1.2-1.5 |
| Polystyrene Foam | 20-35 | 0.15-0.35 | 0.030-0.038 | Class C (ASTM E84) | 0.8-1.0 |
Standard Core Thickness: 48 mm (approximately 1.9 inches) represents the industry standard, providing adequate thermal insulation (U-value ≈ 1.8-2.2 W/m²·K) and acoustic performance (Rw ≈ 30-35 dB) while maintaining reasonable door weight.
Cleanroom doors separating temperature-controlled zones must provide adequate thermal resistance to minimize heat transfer and prevent condensation formation. The thermal transmittance (U-value) quantifies heat transfer rate through the door assembly.
U-Value Calculation:
U = 1 / (Rsi + R₁ + R₂ + R₃ + Rse)
Where:
- Rsi = internal surface resistance (0.13 m²·K/W)
- R₁ = resistance of exterior panel (stainless steel, negligible)
- R₂ = resistance of core material (thickness/thermal conductivity)
- R₃ = resistance of interior panel (stainless steel, negligible)
- Rse = external surface resistance (0.04 m²·K/W)
Thermal Performance by Core Configuration:
| Core Type | Thickness (mm) | U-Value (W/m²·K) | Temperature Differential (°C) | Condensation Risk |
|---|---|---|---|---|
| Paper Honeycomb | 48 | 2.0-2.2 | ≤15 | Low (RH <70%) |
| Aluminum Honeycomb | 48 | 2.3-2.6 | ≤12 | Moderate (RH <65%) |
| Mineral Wool | 50 | 1.6-1.8 | ≤20 | Very Low (RH <75%) |
| Polyurethane Foam | 50 | 1.2-1.4 | ≤25 | Very Low (RH <80%) |
For pharmaceutical cleanrooms maintaining 20-22°C with adjacent areas at 15-18°C, paper or aluminum honeycomb cores provide adequate thermal performance. Facilities with greater temperature differentials (e.g., cold storage access) require enhanced insulation cores.
The adhesive system bonding stainless steel panels to core materials must withstand thermal cycling, humidity exposure, and cleaning chemical contact without delamination or outgassing.
Polyurethane Adhesive Systems:
Two-component polyurethane adhesives (polyol + isocyanate) provide excellent adhesion to stainless steel and core materials. These systems cure through chemical reaction rather than solvent evaporation, eliminating volatile organic compound (VOC) emissions in cleanroom environments.
Key Performance Parameters:
| Property | Specification | Test Method | Significance |
|---|---|---|---|
| Shear Strength | ≥8 MPa | ASTM D1002 | Panel-to-core bond integrity |
| Peel Strength | ≥15 N/mm | ASTM D1876 | Resistance to edge delamination |
| Temperature Resistance | -40°C to +120°C | ASTM D3045 | Thermal cycling stability |
| Maximum Service Temperature | 300°C (short-term) | - | Autoclave/fire exposure |
| Cure Time (23°C) | 24-48 hours | - | Manufacturing cycle time |
| Pot Life | 15-30 minutes | - | Application window |
| VOC Content | <5 g/L | EPA Method 24 | Cleanroom compatibility |
High-temperature polyurethane formulations maintain bond integrity during vaporized hydrogen peroxide (VHP) decontamination cycles (45°C, 70% RH) and resist degradation from repeated exposure to quaternary ammonium compounds, alcohols, and oxidizing agents.
Door perimeter seals prevent air leakage, maintain differential pressure, and block particulate infiltration. Seal performance depends on material properties, compression characteristics, and installation geometry.
Polyurethane Foam Seals:
Two-component polyurethane foam gaskets are formed in place during door manufacturing, creating continuous seals without joints or gaps. The foam expands to fill the gap between door panel and frame, then cures to form a resilient, closed-cell structure.
Polyurethane Seal Properties:
| Property | Value | Test Standard | Requirement Basis |
|---|---|---|---|
| Density | 200-300 kg/m³ | ASTM D1622 | Compression resistance |
| Hardness (Shore A) | 25-35 | ASTM D2240 | Seal compliance |
| Compression Set (22h @ 70°C) | ≤15% | ASTM D395 | Long-term recovery |
| Tensile Strength | ≥1.5 MPa | ASTM D412 | Tear resistance |
| Elongation at Break | ≥200% | ASTM D412 | Flexibility |
| Service Temperature Range | -30°C to +90°C | - | Environmental exposure |
| Aging Resistance | 20 years (predicted) | ASTM D573 | Lifecycle performance |
| Chemical Resistance | Excellent | ASTM D471 | Cleaning agent exposure |
The compression-deflection relationship for polyurethane foam seals follows:
σ = E × ε × (1 + k × ε²)
Where:
- σ = compressive stress
- E = elastic modulus
- ε = strain (compression ratio)
- k = non-linearity coefficient
Optimal seal performance occurs at 25-35% compression, providing adequate contact force (0.5-1.0 N/mm) without excessive door closing force or permanent deformation.
Silicone Rubber Seals:
Silicone elastomer seals offer superior temperature resistance and chemical compatibility compared to polyurethane, making them suitable for autoclavable doors and areas exposed to aggressive cleaning agents.
| Property | Value | Test Standard | Application |
|---|---|---|---|
| Hardness (Shore A) | 40-60 | ASTM D2240 | Standard doors |
| Temperature Range | -60°C to +200°C | - | Autoclave doors |
| Compression Set (70h @ 150°C) | ≤25% | ASTM D395 | High-temperature stability |
| Tear Strength | ≥15 kN/m | ASTM D624 | Durability |
| Ozone Resistance | No cracking | ASTM D1149 | Outdoor exposure |
Air leakage through door assemblies compromises cleanroom classification, increases HVAC energy consumption, and allows cross-contamination between zones. International standards define maximum permissible leakage rates.
EN 12207 Air Permeability Classification:
| Class | Air Permeability (m³/h·m²) @ 50 Pa | Air Permeability (m³/h·m²) @ 100 Pa | Application |
|---|---|---|---|
| Class 0 | No requirement | No requirement | Non-critical areas |
| Class 1 | ≤50 | ≤150 | ISO Class 8-9 cleanrooms |
| Class 2 | ≤27 | ≤50 | ISO Class 7 cleanrooms |
| Class 3 | ≤9 | ≤27 | ISO Class 6 cleanrooms |
| Class 4 | ≤3 | ≤9 | ISO Class 5 cleanrooms, airlocks |
ASTM E283 Air Leakage Test Method:
This standard measures air leakage rate through door assemblies at specified pressure differentials. Test specimens are installed in a chamber, pressure differential is applied, and volumetric flow rate required to maintain pressure is measured.
Typical Performance Values:
| Door Configuration | Leakage Rate (m³/h·m) @ 75 Pa | EN 12207 Class | Suitable Classification |
|---|---|---|---|
| Standard cleanroom door | 1.5-3.0 | Class 3 | ISO Class 6-7 |
| High-performance door | 0.5-1.5 | Class 4 | ISO Class 5-6 |
| Airlock door | 0.2-0.5 | Class 4 | ISO Class 4-5 |
| Hermetic door | <0.1 | Beyond Class 4 | Containment, BSL-3/4 |
Automatic drop seals (also called automatic bottom seals or perimeter seals) deploy when the door closes, creating an acoustic and environmental seal at the door bottom without floor contact during door operation.
Operating Principle:
A spring-loaded or gravity-actuated mechanism extends a flexible seal element (typically silicone or neoprene) when the door closes. The seal contacts the floor surface, blocking the gap between door bottom and threshold. When the door opens, a cam or actuator retracts the seal, eliminating floor friction and wear.
Design Specifications:
| Parameter | Specification | Rationale |
|---|---|---|
| Seal Material | Silicone rubber, Shore A 40-50 | Floor contact durability |
| Seal Width | 25-40 mm | Coverage of floor irregularities |
| Drop Distance | 8-15 mm | Accommodation of floor variations |
| Actuation Force | 5-10 N | Reliable deployment without door binding |
| Cycle Life | >500,000 cycles | 10-year service life @ 100 cycles/day |
| Housing Material | Aluminum alloy 6063-T5 | Corrosion resistance, light weight |
Performance Benefits:
Door hinges must support the door weight, accommodate thermal expansion, resist corrosion, and maintain alignment throughout the door lifecycle. Cleanroom door hinges are typically fabricated from AISI 304 stainless steel with precision-machined bearing surfaces.
Hinge Load Calculation:
For a door of mass M, the load on each hinge depends on door dimensions and hinge placement:
F_hinge = (M × g × L) / (n × d)
Where:
- F_hinge = force on each hinge
- M = door mass (kg)
- g = gravitational acceleration (9.81 m/s²)
- L = distance from hinge axis to door center of mass
- n = number of hinges
- d = vertical distance between hinges
Standard Hinge Configurations:
| Door Height (mm) | Door Width (mm) | Door Mass (kg) | Number of Hinges | Hinge Load (N) | Hinge Size |
|---|---|---|---|---|---|
| 2100 | 900 | 45-55 | 3 | 180-220 | 100 mm × 75 mm |
| 2100 | 1200 | 60-75 | 3 | 240-300 | 120 mm × 75 mm |
| 2400 | 900 | 50-60 | 3 | 200-240 | 100 mm × 75 mm |
| 2400 | 1200 | 70-85 | 4 | 210-255 | 120 mm × 75 mm |
| 2400 | 1500 | 90-110 | 4 | 270-330 | 140 mm × 90 mm |
Three-hinge configurations are standard for doors up to 2400 mm height and 1200 mm width. Wider or heavier doors require four hinges to prevent sagging and maintain seal compression uniformity.
Hinge Material Specifications:
| Component | Material | Surface Treatment | Load Capacity (kg/pair) |
|---|---|---|---|
| Hinge Leaf | AISI 304 stainless steel | Satin finish | 80-120 |
| Hinge Pin | AISI 304 stainless steel | Hardened, polished | - |
| Bearing | Bronze or nylon | - | - |
| Fasteners | AISI 304 stainless steel | Passivated | - |
Ball-bearing hinges provide smoother operation and extended service life compared to plain bearing hinges, particularly for high-traffic applications. The ball bearings distribute load over multiple contact points, reducing friction and wear.
Cleanroom door locks must provide secure latching, smooth operation, and compatibility with cleanroom protocols. Lever handles are preferred over knobs for ergonomic operation and compliance with accessibility standards (ADA, EN 179).
Lock Types and Applications:
| Lock Type | Mechanism | Security Level | Application | Advantages |
|---|---|---|---|---|
| Passage Latch | Spring latch only | Low | Internal cleanroom doors | Free access, no locking |
| Privacy Lock | Push-button lock | Low-Medium | Gowning rooms, offices | Simple operation, emergency release |
| Keyed Lock | Pin tumbler cylinder | Medium-High | Material airlocks, storage | Access control, key management |
| Electronic Lock | Solenoid/motor actuated | High | Controlled access areas | Audit trail, integration with BMS |
| Magnetic Lock | Electromagnetic holding | High | Emergency exits, containment | Fail-safe operation, no mechanical wear |
Lever Handle Specifications:
| Parameter | Specification | Standard Reference |
|---|---|---|
| Material | AISI 304 stainless steel | - |
| Surface Finish | Satin (Ra 0.4-0.8 μm) | - |
| Operating Force | ≤22 N | ADA, EN 179 |
| Return Spring Force | 3-5 N | - |
| Lever Length | 120-140 mm | Ergonomic optimization |
| Lever Projection | 50-65 mm | ADA clearance requirements |
| Warranty Period | 3 years (minimum) | - |
Stainless steel construction ensures corrosion resistance and cleanability. Lever handles should be designed without crevices or recesses that could harbor contamination.
Automatic door closers ensure consistent door closing, maintain differential pressure, and prevent unauthorized access. Cleanroom applications require closers with adjustable closing speed, latching speed, and backcheck functions.
Door Closer Sizing:
Door closers are rated by power size (EN 1154) or spring size (ANSI/BHMA A156.4), which must match door width and mass:
| EN 1154 Power Size | ANSI Spring Size | Maximum Door Width (mm) | Maximum Door Mass (kg) | Application |
|---|---|---|---|---|
| Size 2 | Size 1 | 850 | 40 | Light interior doors |
| Size 3 | Size 2-3 | 950 | 60 | Standard cleanroom doors |
| Size 4 | Size 4 | 1100 | 80 | Heavy or wide doors |
| Size 5 | Size 5 | 1250 | 100 | Extra-heavy doors |
| Size 6 | Size 6 | 1400 | 120 | Maximum capacity |
Adjustable Functions:
| Function | Adjustment Range | Purpose |
|---|---|---|
| Closing Speed | 3-10 seconds (90° to 15°) | Control closing rate |
| Latching Speed | 0.5-2 seconds (15° to 0°) | Ensure positive latching |
| Backcheck | 70-90° | Prevent wall/frame damage |
| Hold-Open | 90-180° (optional) | Temporary door holding |
Material and Finish:
Nickel-plated finishes provide adequate corrosion resistance for most cleanroom environments. Stainless steel closers are available for highly corrosive environments but at significantly higher cost.
Vision panels (observation windows) allow visual communication between cleanroom zones without door opening, reducing contamination risk and improving operational efficiency.
Glass Specifications:
| Property | Specification | Standard | Rationale |
|---|---|---|---|
| Glass Type | Tempered (toughened) safety glass | EN 12150, ASTM C1048 | Impact resistance, safety |
| Thickness | 5-6 mm | - | Structural integrity, safety |
| Visible Light Transmittance | ≥85% | - | Clear visibility |
| Impact Resistance | Class 2 (EN 12600) | EN 12600 | Human impact safety |
| Fire Rating | 30-60 minutes (optional) | EN 1634-1 | Fire-rated door assemblies |
Standard Vision Panel Dimensions:
| Configuration | Width (mm) | Height (mm) | Area (mm²) | Viewing Height (mm) |
|---|---|---|---|---|
| Small | 200 | 300 | 60,000 | 1400-1700 |
| Standard | 300 | 400 | 120,000 | 1350-1750 |
| Large | 400 | 600 | 240,000 | 1200-1800 |
| Full-height | 400 | 1800 | 720,000 | 300-2100 |
Vision panel frames must be constructed from AISI 304 stainless steel with continuous welded construction to prevent crevice formation. The glass-to-frame seal uses silicone sealant (ASTM C920, Type S, Grade NS, Class 25) to accommodate thermal expansion and maintain air-tightness.
Installation Considerations:
Cleanroom door dimensions should align with modular coordination principles (ISO 1006) to facilitate integration with wall panel systems and minimize custom fabrication.
Standard Single-Leaf Door Dimensions:
| Designation | Clear Opening Width (mm) | Clear Opening Height (mm) | Nominal Door Width (mm) | Nominal Door Height (mm) | Application |
|---|---|---|---|---|---|
| 8021 | 800 | 2000 | 926 | 2100 | Personnel access, light material |
| 9021 | 900 | 2000 | 1026 | 2100 | Standard personnel access |
| 10021 | 1000 | 2000 | 1126 | 2100 | Personnel + equipment carts |
| 12021 | 1200 | 2000 | 1326 | 2100 | Wide access, large equipment |
| 9024 | 900 | 2300 | 1026 | 2400 | High ceiling facilities |
| 12024 | 1200 | 2300 | 1326 | 2400 | High ceiling, wide access |
| 15024 | 1500 | 2300 | 1626 | 2400 | Extra-wide access |
Double-Leaf Door Configurations:
| Total Clear Width (mm) | Leaf Width (mm) | Clear Height (mm) | Application |
|---|---|---|---|
| 1600 | 800 + 800 | 2000 | Equipment access |
| 1800 | 900 + 900 | 2000 | Large equipment, pallet access |
| 2000 | 1000 + 1000 | 2000 | Process equipment installation |
| 2400 | 1200 + 1200 | 2300 | Maximum access, machinery |
Dimensional accuracy directly affects door operation, seal performance, and aesthetic appearance. Manufacturing tolerances must be specified and verified during production.
Critical Dimensional Tolerances:
| Dimension | Tolerance | Measurement Method | Impact of Deviation |
|---|---|---|---|
| Door width | ±2 mm | Steel tape, calibrated | Frame fit, seal compression |
| Door height | ±2 mm | Steel tape, calibrated | Frame fit, bottom seal clearance |
| Panel thickness | ±0.5 mm | Micrometer | Core compression, weight |
| Frame squareness (diagonal difference) | ≤3 mm | Diagonal measurement | Door binding, seal gaps |
| Panel flatness | ≤2 mm per meter | Straightedge, feeler gauge | Visual appearance, seal contact |
| Hinge alignment (vertical) | ±1 mm | Plumb bob, level | Door swing, seal compression |
| Reveal (gap) uniformity | ±1 mm | Gap gauge | Visual appearance, air leakage |
Installation Tolerances:
| Parameter | Tolerance | Verification Method |
|---|---|---|
| Frame plumb (vertical) | ±2 mm per 2 m height | Spirit level, laser level |
| Frame level (horizontal) | ±1 mm per meter | Spirit level |
| Frame-to-wall gap | 10-20 mm | Measurement at multiple points |
| Anchor spacing | 400-600 mm centers | Tape measurement |
| Reveal gap (perimeter) | 3-5 mm | Gap gauge, visual inspection |
ISO 14644-1 defines cleanroom classifications based on airborne particulate concentration. Door selection must support the required classification by minimizing particle generation and preventing infiltration.
ISO 14644-1 Cleanroom Classes:
| ISO Class | Maximum Particles/m³ (≥0.5 μm) | Maximum Particles/m³ (≥5.0 μm) | Typical Applications |
|---|---|---|---|
| ISO 3 | 35.2 | - | Semiconductor lithography |
| ISO 4 | 352 | - | Semiconductor manufacturing |
| ISO 5 | 3,520 | 29 | Aseptic processing, filling |
| ISO 6 | 35,200 | 293 | Pharmaceutical manufacturing |
| ISO 7 | 352,000 | 2,930 | Pharmaceutical packaging |
| ISO |