Biosafety cabinets are precision equipment that rely on precise balance of airflow, pressure, filtration, and control for their operation. Once a malfunction occurs, it will directly threaten the safety barrier. The following is a common technical fault analysis based on core principles, divided into phenomena, possible causes, risks, and preliminary treatments.
Malfunctions related to airflow and wind speed
1. Fault phenomenon: Front window airflow alarm (face wind speed too low or too high)
Possible reasons:
Filter blockage: This is the most common cause. The HEPA filter for air supply or exhaust is clogged, causing excessive airflow resistance and preventing the fan from maintaining the set air speed.
Air intake grille blockage: The air intake grille under the front window is covered with experimental supplies, waste, or labels.
Rear exhaust grille blockage: Improper placement of items inside the cabinet has blocked the rear exhaust passage.
Wind speed sensor malfunction/contamination: The sensor probe is contaminated with dust or droplets, resulting in inaccurate readings.
Fan malfunction: Fan motor aging, capacitor damage, belt looseness (some models), or control system failure.
Environmental airflow interference: The safety cabinet is placed at the door, air conditioning outlet, and in areas with frequent movement, which strongly interferes with the airflow and damages the front window curtain.
Improper window frame position: The front window glass has not fully risen to the correct height and is stuck in place.
Risk: If the wind speed is too low (<0.3m/s) to form an effective air curtain, pollutants may leak out; Excessive (>0.7m/s) may generate turbulence, leading to cross contamination inside the cabinet.
Preliminary processing:
Check and remove all items that may block the intake/exhaust grille.
Check if the height of the front window is correct.
After shutting down, gently clean the wind speed sensor probe with an alcohol swab (according to the instructions).
Remove the surrounding interference sources or consider changing the location of the safety cabinet.
2. Fault phenomenon: Abnormal airflow mode (smoke test failed)
Possible reasons:
Filter leakage: The HEPA filter has invisible pinholes or frame sealing failure.
Improper installation of filter: Incorrect installation or sealing after replacement.
Internal wall leakage: Cracks appear at the welding or sealing points of the safety cabinet body (especially after movement or vibration).
Disruption of airflow balance: Severe imbalance between supply and exhaust air ratios, usually related to fan or valve control failures.
Risk: Pollutants may escape directly from the leakage point or form turbulence and dead corners in the work area, rendering both protections ineffective.
Preliminary handling: Stop using immediately. This fault cannot be repaired by the user themselves, and professional personnel must be contacted for integrity leak testing.
Fan and control system malfunction
1. Fault phenomenon: The fan does not turn or makes abnormal noises
Possible reasons:
Power supply issues: power supply not connected, circuit breaker tripped, unstable voltage.
Motor damage: bearing wear, coil burnout.
Capacitor fault: The starting capacitor of the single-phase motor has failed.
Mechanical failure: Fan blade deformation, severe dust accumulation, belt breakage or slippage.
Control board malfunction: The relay or electronic module controlling the fan is damaged.
Risk: The safety cabinet completely loses airflow and has no protective function.
Preliminary processing:
Check the power connection and laboratory main switch.
Listen to the sound and distinguish the position. Abnormal noise may indicate bearing or fan blade problems.
Immediately stop the machine and report for repair. Do not use it forcefully.
2. Fault phenomenon: Control panel malfunction, abnormal display, or false alarm
Possible reasons:
Circuit board malfunction: moisture, dust accumulation, component aging.
Sensor failure: Wind speed, pressure, glass position sensor damage or signal drift.
Software/program error: microprocessor program error (rare).
Risk: Unable to monitor the actual operating status, which may hide serious security risks.
Preliminary handling: Record the fault code and attempt to completely power off and restart. If it is ineffective, professional maintenance is required.
