Safety cabinetBiosafety cabinets, chemical safety cabinets, clean safety cabinets, etc. are key equipment in laboratories that protect personnel, the environment, and samples. Their performance directly affects experimental safety and data accuracy. Regular inspection is the core link to ensure the continuous and effective operation of the safety cabinet, but improper operation during the inspection process may cause cross contamination, equipment damage, and even personal injury. The following outlines key precautions from three stages: preparation before testing, operation during testing, and post-processing after testing, and provides solutions to common problems.
1、 Preparation before testing: Avoid basic risks and ensure the effectiveness of testing
1. Confirm the type and testing standards of the safety cabinet
Biosafety cabinet: It is necessary to test indicators such as airflow velocity, personnel protection, and product protection in accordance with GB 19489-2008 General Requirements for Laboratory Biosafety or NSF/ANSI 49-2022.
Chemical safety cabinet: Referring to the "JG/T 385-2012 Code for Design of Ventilation Systems in Chemical Laboratories", the focus is on testing corrosion resistance and gas leakage rate.
Clean safety cabinet: Detect suspended particle concentration and airflow organization according to ISO 14644-1:2015.
Risk point: Confusion of standards may result in missing testing items (such as failure to test the integrity of HEPA filters in biosafety cabinets).
2. Personnel qualifications and protection
Testing personnel: They need to hold a "Biosafety Laboratory Personnel Qualification Certificate" or a "Professional Technical Personnel Certificate for Occupational Health Technical Service Institutions", and be familiar with the structure and risks of safety cabinets.
Personal protective equipment (PPE): N95 masks, double layered gloves, and protective clothing should be worn when testing biosafety cabinets; When testing chemical safety cabinets, gas masks and acid and alkali resistant aprons should be equipped.
Case: A laboratory did not require testing personnel to wear goggles, resulting in chemical reagents splashing into the eyes and causing minor burns.
3. Equipment and tool calibration
Testing instruments such as anemometers, particle counters, aerosol generators, etc. need to be calibrated in advance to national measurement standards with an error range of ≤ 5%.
Backup tools: Prepare spare batteries, sensors, filter membranes, and other vulnerable parts to avoid testing interruptions.
Data: An uncalibrated anemometer may result in a measurement deviation of up to 20% in airflow velocity, directly affecting the classification judgment of the safety cabinet.
4. Environment and sample preparation
Environmental conditions: Close the laboratory doors and windows one hour before testing to avoid external airflow interference; The temperature should be controlled between 18-26 ℃ and the humidity should be ≤ 60%.
Sample simulation: For biosafety cabinet testing, simulated samples (such as culture dishes) need to be placed, while for chemical safety cabinets, corrosive liquid containers need to be placed to verify their performance in actual usage scenarios.
Risk point: Excessive environmental humidity may cause abnormal particle counter data, and dehumidification is required in advance.
2、 Operation during testing: precise control of variables to ensure reliable data
1. Airflow velocity detection
Inlet air velocity: measured at three points on the working window of the safety cabinet, including the top, middle, and bottom, with an error of ≤ 0.025m/s (according to the standard of Class II A2 biological safety cabinet).
Exhaust speed: Check the air speed at the exhaust outlet to ensure it matches the intake speed (e.g. A2 type exhaust speed should be 10% higher than the intake speed).
Common error: Placing the anemometer probe close to the filter membrane or grid can cause data to be inflated; The probe should be kept at least 15cm away from the surface of the filter membrane.
2. Personnel and product protection testing
Personnel protection: The biosafety cabinet should be tested for aerosol leakage rate in the operating area using the KI disus method or potassium iodide method, and the result should be ≤ 3 × 10 ⁻ ³/min.
Product protection: Place sensitive samples (such as bacterial cultures) in the safety cabinet to detect external contamination entering the work area.
Risk point: If the respiratory rate of the testing personnel is too fast, it may cause airflow disturbance. It is necessary to maintain stable breathing or use a breathing mask.
3. Filter integrity testing
HEPA filter: using DOP (dioctyl phthalate) or PAO (poly alpha olefin) aerosol generator, detect the concentration ratio upstream and downstream of the filter, and the leakage rate should be ≤ 0.01%.
Chemical filter: The adsorption efficiency of specific gases (such as formaldehyde and benzene) detected by activated carbon filter should be ≤ 5% of the initial concentration.
Case: A laboratory failed to test the integrity of the filter, resulting in the leakage of virus aerosols in subsequent experiments and causing personnel infection.
4. Noise and vibration detection
Noise: Measured 1m in front of the safety cabinet and 1.2m above the ground, the noise level should be ≤ 65dB (Class A).
Vibration: Use a vibration meter to detect the amplitude of the workbench vibration, which should be ≤ 5 μ m (to prevent affecting precision experiments).
Risk point: Excessive noise may damage hearing, requiring earplugs or adjusting fan frequency.
3、 Post detection processing: prevent secondary pollution and ensure equipment recovery
1. Cleaning and disinfection
Biosafety cabinet: Wipe the workbench, grille, and exhaust outlet with 75% ethanol, and then irradiate with ultraviolet light for 30 minutes.
Chemical safety cabinet: Clean corrosive residues with a neutralizing agent (such as sodium bicarbonate solution), and then rinse with deionized water.
Risk point: Incomplete disinfection may lead to cross contamination, and validated disinfectants should be used.
2. Data recording and reporting
Original records: Detailed records of testing time, environmental conditions, instrument model, testing points, values, and reasons for deviations.
Report template: A report shall be issued in a standard format, specifying the conclusions of "qualified", "rectification within a specified period" or "suspension of use", and signed by the testing personnel and laboratory manager.
Case: A certain testing report did not indicate environmental humidity, resulting in data being questioned during subsequent audits.
3. Equipment reset and identification
Reset: Set the safety cabinet to normal working mode (such as air speed and temperature), and turn off all detection interfaces.
Identification: Post a "Qualified Inspection" label on the device, indicating the next inspection date; If it is not qualified, a "stop use" label should be affixed and isolated.
Risk point: Failure to reset may result in abnormal experimental conditions in the future (such as low wind speed).
4、 Common Problems and Solutions
| Problem phenomenon | Possible reasons | Solution |
| Detecting large fluctuations in data | External airflow interference, instrument not calibrated | Close doors and windows, recalibrate instruments |
| Filter leakage rate exceeds the standard | The filter is damaged and not installed properly | Replace the filter and reseal it |
| The noise level is too high | Wear of fan bearings and blockage of air ducts | Replace bearings and clean air ducts |
| The device cannot start after detection | Power line malfunction, damage to control board | Check the circuit and contact the manufacturer for repair
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Compliance: Strictly follow national standards and equipment manuals to avoid "empirical" operations. Summary: Core Principles of Safety Cabinet Inspection
Safety: prioritize personnel protection to prevent infection, poisoning, or mechanical injury during the testing process.
Accuracy: Control environmental variables, calibrate instruments, standardize operations, and ensure data traceability.
Traceability: Complete recording of the testing process and results, providing a basis for equipment maintenance and laboratory certification.
The laboratory can systematically reduce testing risks and ensure experimental safety and data quality by developing the "Safety Cabinet Testing SOP", regularly training testing personnel, establishing instrument calibration files, and other measures.