Tool 19: Cleanroom Equipment & Decontamination
Cleanroom Air Shower & Dynamic Pass Box Sizing
Dimensions HEPA-filtered cleanroom entry equipment per ISO 14644 and FDA cGMP Annex 1. Computes nozzle jet velocity, total recirculating CFM/CMH, chamber air change rates, volumetric chamber sweeps per cycle, and centrifugal blower motor power.
✔ 1. Formula Verified
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⚡ 2. Engineering Screening
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📐 3. Standards Referenced (ISO 14644 / FDA cGMP)
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⚖ 4. Engineer Review Required
Decontamination Equipment Parameters
Type
Persons
Chamber internal volume sized at ~2.5 m³ per person.
Nozzles
Adjustable stainless steel 304 nozzles distributed across side walls and ceiling.
mm
Standard orifice: 25 mm (1 inch) or 32 mm for concentrated particulate scrubbing.
m/s
Design exit velocity (standard ≥ 20.0 m/s ≈ 4000 FPM per ISO 14644).
Seconds
Programmable interlocked cycle timer (typically 15–25 seconds).
Equipment Sizing Sheet
Preliminary Screening
Total Recirculation Airflow
366 CFM
Volumetric Flow: 622 CMH with H14 HEPA (99.995% efficiency)
Air Discharge Velocity
22.0 m/s
Hourly Air Changes
248.8 ACPH
Volumetric Sweeps / Cycle
1.38 Sweeps
Velocity Standard Check
Pass (≥ 20 m/s)
Estimated Blower Motor Rating
1.0 HP / 0.75 kW (Theor. Input: 0.235 kW, 3.20× Commercial Motor Selection Margin)
Governing Engineering Standards & Calculation Model
Governing Standards & References
- ISO 14644-1: Classification of air cleanliness by particle concentration.
- US FDA cGMP Annex 1 / WHO TRS 986: Manufacture of sterile medicinal products (Personnel and material airlocks).
- IEST-RP-CC002: Unidirectional-Flow Clean-Air Devices.
Engineering Equations & Derivations
Air Shower Aerodynamics:
A_nozzle = π × (d_mm / 2000)² = 0.000491 m²
Q_m³/s = N_nozzles × A_nozzle × Exit_Velocity [m/s] = 0.1728 m³/s
CFM = Q_m³/s × 2118.88 (366 CFM); CMH = Q_m³/s × 3600 (622 CMH)
ACPH = (Q_m³/s × 3600) / (Persons × 2.5 m³) = 248.8 ACPH
Sweeps = (Q_m³/s × Cycle_sec) / Cabin_Volume = 1.38 Sweeps
Blower Power Physics (750 Pa, η_fan=0.65, η_motor=0.85):
P_air = (Q × ΔP) / 1000 = (0.1728 × 750) / 1000 = 0.1296 kW
P_shaft = P_air / 0.65 = 0.1994 kW
P_elec = P_shaft / 0.85 = 0.2345 kW (0.31 HP)
Selected Commercial Motor: 1.0 HP (0.75 kW) [3.20× Commercial Motor Selection Margin]
Note: Final fan curve, system resistance, filter loading, starting characteristics, duty cycle and manufacturer data require project-specific verification.
Dynamic Pass Box:
Q_m³/h = Chamber_Vol × 60 ACPH (Class B/C Purge)
A_nozzle = π × (d_mm / 2000)² = 0.000491 m²
Q_m³/s = N_nozzles × A_nozzle × Exit_Velocity [m/s] = 0.1728 m³/s
CFM = Q_m³/s × 2118.88 (366 CFM); CMH = Q_m³/s × 3600 (622 CMH)
ACPH = (Q_m³/s × 3600) / (Persons × 2.5 m³) = 248.8 ACPH
Sweeps = (Q_m³/s × Cycle_sec) / Cabin_Volume = 1.38 Sweeps
Blower Power Physics (750 Pa, η_fan=0.65, η_motor=0.85):
P_air = (Q × ΔP) / 1000 = (0.1728 × 750) / 1000 = 0.1296 kW
P_shaft = P_air / 0.65 = 0.1994 kW
P_elec = P_shaft / 0.85 = 0.2345 kW (0.31 HP)
Selected Commercial Motor: 1.0 HP (0.75 kW) [3.20× Commercial Motor Selection Margin]
Note: Final fan curve, system resistance, filter loading, starting characteristics, duty cycle and manufacturer data require project-specific verification.
Dynamic Pass Box:
Q_m³/h = Chamber_Vol × 60 ACPH (Class B/C Purge)
⚖ Statutory Notice & Engineering Disclaimer (Tier D Integration)
Air showers reduce surface particulate contamination on cleanroom personnel gowns before entry into ISO Class 5 to 7 cleanrooms. They are not biological sterilizers. Nozzle velocities must be calibrated during annual cleanroom validation using calibrated hot-wire anemometers. High-velocity HEPA filter seal integrity must be validated by DOP/PAO aerosol leak testing per ISO 14644-3.