What are the standards and requirements for cleanliness in purification workshop installation?

The core of purification workshop's installation is grading according to ISO 14644-1/GB 50073-2013, controlling particles and microorganisms, ensuring airflow/pressure difference/temperature and humidity, sealing and filtering, and strict acceptance. The following are complete standards and installation requirements.

A, cleanliness grade standard (core basis)

GB 50073-2013 Code for Design of Clean Workshop is implemented in China, and ISO 14644-1 is adopted internationally. The classification is based on * * particle concentration ≥ 0.5μ m (unit: one/m):

form

Common application of domestic ISO grade ≥ 0.5μ m maximum limit ≥ 5μ m maximum limit.

100-level ISO 5 ≤3,520 0 Medical aseptic filling and semiconductor lithography

Thousands of ISO 6 ≤ 35,200 ≤ 293 Precision electronic and medical instruments

Ten thousand ISO 7 ≤ 352,000 ≤ 2,930 Electronic assembly and food packaging

One hundred thousand ISO 8 ≤ 3,520,000 ≤ 29,300 General electronics and food processing

Note: The smaller the grade, the cleaner it is; The inspection is divided into * empty state/static state/dynamic state, with dynamic state as the final acceptance standard. *

Second, the installation core requirements (directly affect the cleanliness)

1. Enclosure structure (no dust, no air leakage)

Wall/ceiling: 50mm machine-made rock wool/glass magnesium color steel plate with smooth surface, scrub resistance and no dust accumulation angle; Yin and Yang Angle arc transition (R≥50mm).

Floor: epoxy self-leveling, PVC or antistatic floor; Seamless, wear-resistant and easy to clean; The electronic workshop should be antistatic (surface resistance is 10–10 Ω).

Doors and windows: closed and clean doors/windows, with sealed gaps; The glass is double-layer hollow; Door interlock (to prevent pressure difference damage).

Sealing: all seams, through-wall holes and equipment interfaces are tightly sealed with sealant/foaming agent; Air tightness is the first guarantee of cleanliness.

2. Air distribution (determining the upper limit of cleanliness)

Unidirectional flow (laminar flow): ISO grade 5 and above; Full of high efficiency filters (FFU), wind speed of 0.3–0.5m/s, vertical/horizontal unidirectional flow, no dead angle.

Non-unidirectional flow (turbulent flow): ISO 6–8 grade; Top air supply and lower return air; Ventilation times:

ISO 7 (ten thousand): 25–40 times/hour.

ISO 8 (class 100,000): 15–25 times/hour.

Tuyere layout: efficient air supply outlets are evenly distributed; The air return port is equipped with a medium-effect filter to avoid short circuit.

3. Three-stage filtration system (core purification)

Primary effect (G4): intercepting large particles ≥5μm, which is necessary for fresh air inlet.

Medium efficiency (F8): intercept 1–5 μ m particles and protect the high efficiency filter.

High efficiency (HEPA/ULPA):

Iso grade 5: ULPA (efficiency ≥99.999% for 0.12μm)

Iso 6–8: HEPA (efficiency ≥99.97% for 0.3μm)

Installation points: the high-efficiency filter must be leak-proof (PAO method), and there is no leakage; The frame is sealed and compacted evenly.

4. Differential pressure control (pollution prevention)

Clean area → quasi-clean area → unclean area: positive pressure step by step.

Differential pressure between adjacent clean areas: ≥5Pa

Pressure difference between clean area and non-clean area: ≥10Pa

Installation: install micro-pressure differential meter for real-time monitoring; Fresh air volume ≥ exhaust air volume+positive pressure air volume.

5. Temperature and humidity and environmental control

Temperature: electronics/precision manufacturing 22 2℃; Medicine/food 20–26℃.

Humidity: 45%–60% RH; Anti-static and anti-microbial.

Electrostatic control: ground/equipment grounding resistance * * ≤ 1Ω * *; Personnel shall be equipped with anti-static wrist strap; Ion fans are set in key areas.

Vibration control: the vibration speed in the precision equipment area is ≤ 0.1μ m/s (1–100 Hz); Independent damping foundation.

6. Microbial control (medicine/food must reach)

Plankton: ISO 5 ≤ 100 cfu/m; Iso grade 7 ≤ 500 cfu/m.

Sedimentation bacteria: ISO grade 5 ≤3 CFU/dish; Iso grade 7 ≤10 CFU/dish.

Measures: ozone/ultraviolet disinfection, special sanitary ware in clean area, and personnel changing clothes in air shower.

7. Personnel and material purification (installation)

People flow: changing clothes → shoes → air shower (≥15s, wind speed ≥20m/s)→ clean area.

Logistics: materials → buffer room → transfer window (ultraviolet disinfection) → clean area; Transmission window interlock.

Iii. Installation acceptance criteria (inspection required)

Cleanliness detection: laser particle counter, distributed according to ISO 14644-1, reaching the standard dynamically.

High-efficiency filter leak detection: PAO aerosol leak detection, the leakage rate **≤0.01%**.

Differential pressure detection: the differential pressure in all areas meets the gradient requirements.

Ventilation frequency/wind speed: measured value ≥ design value.

Temperature and humidity, static electricity and microorganism: tested according to industry standards.

Four, the industry common level reference

Medicine (GMP): aseptic filling → ISO 5; Oral preparations → ISO 7–8.

Electronic semiconductor: lithography → ISO 3–5; Packaging test → ISO 6–7.

Food/cosmetics: clean packaging → ISO 7–8.

Precision machinery/optics: assembly → ISO 6–7.

Five, the installation of pit avoidance points

Do air tightness test first, and then install high efficiency filter.

Air duct/equipment shall be cleaned, disinfected and sealed after installation to avoid secondary pollution.

Construction shall be carried out in strict accordance with drawings and specifications, and openings and diversions shall not be made at will.

After the completion of continuous self-purification for 30 minutes or more and then test.