Key Installation Notes for Cleanroom Engineering in Medical Industry

1. Pre-construction Embedding & Construction Sequence Control

Follow construction sequence: concealed works → enclosure structure → electromechanical installation → final HEPA filter setup; avoid slotting and drilling after wall panel installation.

Build 100mm-high concrete anti-seepage concrete parapet along base of partition walls to block moisture and mold migration. Sink floor by 300~400mm with drainage slope for cleaning rooms and waste rooms with water supply.

Pre-embed airtight sleeves for ducts, medical gas pipes and electric conduits penetrating walls/ceilings; seal gaps with waterproof filler after civil works completion. No operable exterior windows inside clean areas; seal original open windows completely.

Isolate clean zone from ordinary area physically. Remove outer packaging and dust off all materials before moving into clean area; workers wear cleanroom shoes and caps to control on-site dust.

2. Enclosure Installation (Sandwich Panel, Flooring & Doors)

Wall & Ceiling Panels

Adopt 50mm antibacterial rock wool/honeycomb sandwich panels with interlocking joints; fill all seams with medical mildew-proof neutral silicone sealant with zero visible gap.

Install R50mm curved aluminum profiles for all internal corners (wall-floor, wall-ceiling, wall-wall) to eliminate dead corners prone to dust and bacteria accumulation (mandatory medical specification).

Pre-embed independent load-bearing hangers for surgical ceiling pendants and IV rails; never suspend heavy fittings on ceiling keel of sandwich panels.

Seal openings for penetrating pipes with fire-resistant sealant to prevent air leakage and cross-contamination.

Flooring (Homogeneous PVC / Epoxy Self-leveling Floor)

Base concrete strength ≥C20, moisture content＜8%, flatness ≤2mm per 2m span without hollowing or sanding. Lay damp-proof layer prior to top flooring; strengthen moisture insulation for humid southern regions.

Hot-weld seamless joints for PVC sheets; pre-embed copper grid (1.2m×1.2m) for anti-static cleanrooms with qualified earthing resistance.

Ban regular floor drains in Class A/B (Class 100) clean areas; adopt sealed water-sealed dedicated cleanroom floor drains for general spaces to block odor backflow.

Doors & Pass-through Hatches

Equip airtight rubber gaskets on cleanroom doors with automatic door closer; pass-through hatches adopt mechanical interlock to avoid simultaneous opening of double doors and cross air contamination.

Recess door frames with full perimeter sealing.

3. HVAC Purification System Installation

Air Duct Fabrication & Installation

Prefabricate galvanized steel ducts off-site; remove burrs and welding slag on inner surface, clean with neutral detergent, dry and cover with protective film; peel films only during field installation.

Use vibration-damping hangers and 5mm closed-cell sponge flange gaskets for full sealing; apply firestop filler for ducts penetrating fire walls.

Conduct full air leakage & light leakage inspection; high-pressure duct air leakage rate ≤1%.

Filter Installation

Install primary & medium efficiency filters first; mount HEPA filters only after full room cleaning and 24h continuous system pre-blow to prevent filter contamination.

Adopt liquid tank sealing (sealant depth ≥8mm); perform on-site PAO aerosol leak test for each HEPA unit and replace defective filters.

Install terminal HEPA + check valve on exhaust duct of negative-pressure OR to prevent outdoor pollutant backflow.

Differential Pressure & Airflow Control

Maintain step-down pressure gradient: clean area → buffer room → waste room; clean area keeps +10Pa vs non-clean area, buffer room 5~10Pa, negative isolation OR -8~-10Pa.

Air change rate: Class I OR ≥36 times/h, standard OR ≥24 times/h, Class 10,000 ICU ≥15 times/h; unidirectional airflow speed at surgical zone 0.25~0.35m/s.

Temperature & humidity: OR 22~25℃, RH 50%~60%; fresh air volume ≥40m³/h per person.

4. Special Medical Piping Works (Medical Gas, Water & Purified Water)

Medical Gas Pipeline (Oxygen, Vacuum, Nitrogen)

Use 316L stainless steel pipe with orbital TIG welding; conduct internal degreasing & purge; recess medical gas outlets 1.0~1.2m above finished floor at anaesthesia side with zero leakage.

Keep vacuum pipeline gradient ≥0.5% for condensate drainage to avoid water backflow.

Domestic Sewage & Clean Water

Install induction stainless steel sinks with water-sealed trap; seal pipe penetration points; prohibit direct sewage discharge from clean zone into ordinary trench.

Adopt 316L stainless steel tubing for purified water with orbital welding & passivation; pipe slope ≥1% to eliminate stagnant water dead legs.

5. Electrical & Weak Current Installation (per GB16895.24)

Conceal conduits as much as possible with sealed sleeves at panel penetration; recess sockets & distribution boxes flush to wall with full perimeter sealing for dustproof purpose.

Install recessed hermetic cleanroom lamps with sealed gaskets; illuminance ≥400lx for OR and ≥200lx for auxiliary rooms.

Class I power supply with dual incoming feed + UPS backup for OR & ICU; independent equipotential earthing system.

Preinstall sensors for differential pressure, temperature, humidity and CO₂ for central control linkage with variable-frequency air conditioner.

6. Fire Protection & Negative Pressure Special Requirements (Infectious Disease Ward / Negative OR)

Recess sprinklers and smoke detectors with sealed covers; full firestopping for all penetrations through fire barriers.

Independent high-level exhaust system for negative isolation wards; exhaust air shall not connect to common ventilation duct. Regular leakage inspection and disinfection for exhaust HEPA filters.

7. Final Cleaning & Acceptance Check

Three-stage cleaning: rough sweeping → neutral detergent wiping → ultrapure water wipe with lint-free cloth; run full-system continuous blow for minimum 72 hours afterward.

Mandatory acceptance tests: HEPA leak test, room differential pressure, air change rate, temperature/humidity, airborne particle count, settling bacteria concentration and anti-static floor resistance before handover to hospital.