How should a cleanroom for food production be rationally laid out?

The core of food processing cleanroom layout is based on unidirectional process flow, three-level cleanroom zoning, strict separation of personnel and material flow, pressure differential and airflow directionality, physical isolation to prevent cross-contamination, and compliance with standards such as GB 14881 and GB 50073.

I. General Layout Principles (Compliance + Contamination Prevention)

Unidirectional Process Flow: Raw materials → Pre-treatment → Processing → Inner packaging → Finished product, without cross-flow, backflow, or detours.

Three-Level Cleanroom Zoning (Physical Isolation)

General Work Area (Non-Clean): Raw material receiving, rough washing, thawing, waste disposal, external cleaning of packaging materials.

Semi-Clean Area (ISO8 / Class 100,000): Semi-finished product processing, packaging preparation, secondary changing, buffer corridor.

Clean Area (ISO7 / Class 10,000 ~ ISO8): Ready-to-eat food cooling, aseptic inner packaging, sealing, metal detection.

Complete Separation of Personnel and Material Flow: Raw material inlet ≠ finished product outlet, personnel passage ≠ material passage.

Pressure differential and airflow orientation: Clean area → Semi-clean area → General area, with pressure differentials ≥5Pa and ≥10Pa respectively. Airflow flows from high cleanliness to low cleanliness to prevent backflow.

High cleanliness area is centrally located/upwind: High-risk areas such as aseptic packaging and cooling are located inside or in the center of the workshop, away from doors, windows, and external corridors.

II. Standard Functional Zoning and Flow Design

(I) Personnel Flow (Changing → Clean Area, Backward Movement Strictly Prohibited)

Entrance → Shoe Changing Area → First Changing (Removing Outer Clothing) → Handwashing → Second Changing (Wearing Clean Gown/Cap/Mask) → Air Shower → Clean Area.

Changing area: 0.5–0.8㎡/person; Air shower ≥800×800×2000mm per person.

Doors in each area are interlocked to prevent pressure differential failure caused by simultaneous opening.

(II) Logistics Flow (Raw In, Cooked Out, One-Way Closed Loop)

Raw Material Inlet → Raw Material Temporary Storage → Pre-treatment (Rough Washing/Thawing) → Pass-through Window (UV Disinfection) → Fine Processing/Blending → Sterilization → Cooling (Clean Area) → Aseptic Inner Packaging → Outer Packaging → Finished Product Temporary Storage → Finished Product Outlet.

Raw material and finished product channels are completely separated; raw and cooked areas are physically separated by walls and have independent ventilation.

Pass-through windows are equipped with UV disinfection for ≥30 minutes and can only be opened in one direction.

(III) Key Points of Functional Area Layout

Raw Material Storage: Located near the raw material inlet, cool and dry, protected from rodents and insects, with a buffer room between it and the pre-treatment area.

Processing Area: Arranged according to the process sequence, with equipment spacing ≥1m for easy cleaning and maintenance; high-humidity/high-odor processes (such as steaming, frying) are located on the leeward side and have independent exhaust ventilation.

Inner Packaging/Clean Area: The innermost part of the workshop, ISO 7–8 level, positive pressure ≥5Pa, equipped with laminar flow/FFU, with direct food contact processes centrally located.

Outsourced Area: Outside the clean area, near cleanliness level, with a buffer room/pass-through window between the outsourced area and the inner packaging area.

Finished Product Storage: Located near the finished product exit, with controllable temperature and humidity, stored off the ground and away from walls.

Auxiliary Areas:

Handwashing and Disinfection: Non-contact faucets, hand dryers, and disinfectant, located after the second changing of clothes/at the entrance to the clean area.

Tool Cleaning and Disinfection: Dedicated room, isolated from the production area to prevent cross-contamination.

Inspection Room: Independently set up, separated from the production area to avoid interference and contamination.

III. Key Hardware and Environmental Control

Building and Materials: Color steel plate/stainless steel partitions sealed to the ceiling; non-slip and easy-to-clean floor with a 1.5‰–2‰ slope for drainage; rounded corners for easy cleaning.

Pressure Differential and Ventilation: Clean area to non-clean area ≥10Pa; Air Change Rate: ISO 7 ≥25 times/h, ISO 8 ≥15 times/h; Independent exhaust and deodorization for high humidity/odor areas.

Cleanliness Indicators (Dynamic)

ISO7 (Class 10,000): ≥0.5μm particles ≤3.52 million/m³, airborne bacteria ≤100 CFU/m³.

ISO8 (Class 100,000): ≥0.5μm particles ≤35.2 million/m³, settling bacteria ≤10 CFU/plate.