The validation of a clean workbench is a key step in ensuring that its performance meets design requirements and meets clean environmental standards. It usually requires systematic validation of core indicators such as structural integrity, airflow organization, cleanliness, microbial control, vibration, and noise. The following are specific verification methods and operational points:
1、 Preparation before verification
Document verification
Check the factory certificate, user manual, and maintenance records of the equipment to confirm that the equipment model, specifications, and design requirements are consistent.
Confirm that the verification plan has been approved, including verification purpose, scope, methods, acceptance criteria, and personnel division.
Confirmation of environmental conditions
Verify that the environmental temperature and humidity meet the equipment requirements (such as temperature of 18-26 ℃ and humidity of 45-65%).
Ensure that there is no strong airflow interference in the verification area (such as direct air conditioning, open doors and windows) to avoid affecting airflow organization testing.
instrument calibration
Use calibrated instruments for testing, including:
Particle counter: used to detect cleanliness (such as the number of particles in 0.5 μ m and 5 μ m).
Anemometer: measures the wind speed in the work area.
Microbial sampler: collects air or surface microbial samples.
Sound level meter: measures noise levels.
Vibration meter: detects the amplitude of vibration during equipment operation.
2、 Core Verification Projects and Methods
1. Structural and visual inspection
Purpose: To confirm that the equipment is undamaged, has good sealing, and meets the design specifications.
Method:
Visually inspect the workbench shell, operation panel, and glass windows for completeness, without cracks or deformations.
Check if the HEPA/ULPA high-efficiency filter is securely installed and if the sealing strip is not aged or detached.
Confirm that the lighting fixtures and ultraviolet lamps (if any) are working properly, without flickering or damage.
Acceptance criteria:
Complete structure with no visible defects; The filter has good sealing and no risk of leakage.
2. Airflow organization verification
Purpose: To ensure that the airflow direction in the workspace is correct, the wind speed is uniform, and to avoid eddies or blind spots.
Method:
Wind speed test:
Arrange measuring points evenly in the workspace (such as using the 5-point or 9-point method) and measure the vertical airflow velocity using an anemometer.
The recommended testing height is 10-15cm above the working surface (or the height specified in the equipment manual).
Airflow direction test:
Use a smoke generator (such as tetrabutyl titanate smoke) to release smoke in the work area, and observe whether the airflow direction is vertically downward, without backflow or vortex.
Acceptance criteria:
Wind speed: 0.3-0.5m/s (ISOClass5/100 level) or 0.4-0.6m/s (ISOClass4/10 level), and the deviation of each measuring point is ≤± 20%.
Airflow direction: vertically downward, without obvious eddies or backflow.
3. Cleanliness verification
Purpose: To confirm that the air cleanliness in the workspace meets the design level (such as ISO Class 5/100).
Method:
Dynamic testing: When the device is running normally (fan on, lighting on), use a particle counter to continuously sample 3 times, with each sampling time ≥ 1 minute.
Static testing: After running the equipment without load for 30 minutes, sample according to the above method.
Measurement point arrangement:
The center, corners, and edges of the workspace (5-9 points in total) are 10-15cm above the working face.
Acceptance criteria:
ISOClass5 (Class 100): The number of particles ≥ 0.5 μ m ≤ 3520/m ³ (or ≤ 3.52/L), and the number of particles ≥ 5 μ m is 0.
The dynamic test results must meet at least 80% of the static standards.
4. Microbial control validation
Purpose: To confirm that the microbial contamination level in the work area meets the requirements (such as total bacterial count ≤ 1 CFU/dish · 30 minutes).
Method:
Air sampling: Use sedimentation method or planktonic bacterial sampler, place nutrient agar culture dish in the center of the work area, expose for 30 minutes, and incubate at 30-35 ℃ for 48 hours to count the number of bacterial colonies.
Surface sampling: Use a sterile cotton swab to wipe the inner surface of the workbench (such as the operating table and side walls), inoculate it onto the culture medium, and count the number of bacterial colonies after cultivation.
Acceptance criteria:
Total number of airborne bacteria: ≤ 1 CFU/dish · 30 minutes (ISO Class 5 environment).
Total number of surface bacteria: ≤ 0.1 CFU/cm ² (critical surface).
5. Vibration and Noise Verification
Purpose: To ensure smooth operation of the equipment, and that vibration and noise do not affect experimental operations.
Method:
Vibration test: Place vibration meters at the four corners and center of the workbench to measure the vibration amplitude (unit: mm/s ²) of the equipment during operation.
Noise test: Use a sound level meter to measure the noise level (in dB (A)) at a distance of 1 meter outside the work area.
Acceptance criteria:
Vibration amplitude: ≤ 5mm/s ² (vertical direction).
Noise level: ≤ 65dB (A) (during no-load operation).
6. Differential pressure verification (if applicable)
Purpose: To confirm that the pressure difference between the clean workbench and the surrounding environment meets the requirements (such as positive pressure ≥ 10Pa), in order to prevent external contamination from entering.
Method: Use a micro differential pressure gauge to measure the pressure difference between the working area and adjacent areas.
Acceptance criteria: Positive pressure ≥ 10Pa (or the value specified in the equipment manual).
3、 Post validation processing
Data organization and analysis
Summarize the test data into the validation report, draw wind speed distribution maps, particle number trend maps, etc., and visually display the validation results.
Compare the measured values with the acceptance criteria to determine if the equipment is qualified.
Nonconforming product handling
If a certain indicator is not qualified, the reason needs to be analyzed (such as filter damage, fan failure), repaired, and re verified.
The number of repeated verifications is generally not more than 2 times. If it still fails, the equipment should be stopped and the manufacturer should be contacted for maintenance.
validation cycle
First verification: after equipment installation and before putting it into use.
Regular verification: once every six months or one year (adjusted according to usage frequency and risk level).
Change verification: Re verification is required after replacing filters, repairing, or when environmental conditions change.