What are the precautions for the daily application of laminar flow hoods?

Laminar flow hoods need to be strictly managed from multiple dimensions such as equipment inspection, operation norms, maintenance and care, and safety protection in daily applications to ensure their clean effect and operational safety. The following are detailed precautions for different scenarios:
I. Preparations and Inspections before Operation
1. Equipment status verification
Power supply and circuit: Confirm that the power supply voltage is consistent with the rated value of the equipment (such as 220V/380V), check that the wires are undamaged and the grounding resistance is ≤4Ω to avoid the risk of electric leakage.
Filter performance: Monitor the resistance of the high-efficiency filter (HEPA/ULPA) through a differential pressure gauge. If it exceeds the initial value by 1.5 times (for example, initially 200Pa and now reaching 300Pa), it needs to be replaced in time to prevent insufficient air volume.
Fan operation: Manually rotate the impeller to confirm there is no jamming. When starting, listen for any abnormal sounds from the motor to prevent overload damage.
2. Environmental and installation requirements
Installation location: Keep away from sources of airflow disturbance such as doors, Windows, and air conditioning vents, and maintain a distance of no less than 50cm from the wall. The height of the vertical flow laminar flow hood from the working surface is recommended to be 1.2-1.5 meters to prevent short-circuiting of the airflow.
Temperature and humidity control: In conjunction with the air conditioning system, maintain the ambient temperature at 18-26℃ and the humidity at 45%-65% to prevent high humidity from causing condensation on the filter or rusting of the equipment.
Ii. Operating Norms during Operation
Core requirements for airflow management
Face wind speed monitoring: Use an anemometer for regular detection (vertical flow 0.36-0.54m/s, horizontal flow 0.45±0.2m/s). When the wind speed is 20% lower than the standard, check for filter blockage or fan speed.
Personnel and item control: During operation, avoid rapid movement or frequent hand raising in front of the laminar flow hood. Items should be slowly placed from the side to prevent interference with unidirectional flow.
2. Special operations in different industries
Medical/biological scenarios:
Turn on the machine 30 minutes before surgery or experiment. After use, turn on the UV lamp to sterilize for 30 minutes (avoid direct ultraviolet radiation on the human body).
When handling infectious samples, ensure that the exhaust air is connected to a biosafety filtration system to prevent aerosol leakage.
Electronic/semiconductor scenarios:
Operators must wear anti-static clothing (grounding resistance ≤10Ω), and tools should be disinfected with alcohol. The use of volatile solvents (such as acetone) is strictly prohibited.
Iii. Daily Maintenance and Disinfection
Frequency of cleaning and disinfection
Daily cleaning: Wipe the inner walls, countertops, and lampshades with 75% alcohol; In medical Settings, the surgical area should be wiped with emphasis to prevent bacterial growth.
Weekly deep cleaning: Disassemble components such as the grille and air intake screen, wash them with neutral detergent, and dry them. The pharmaceutical workshop can be sterilized by fumigation with formaldehyde or vaporized hydrogen peroxide (VHP) and then ventilated for 4 to 6 hours after sterilization.
2. Filter replacement standards
High-efficiency filter (HEPA): Replace it every 1-2 years in regular environments and every 6-12 months in highly polluted scenarios (such as operating rooms). When replacing, wear dust-proof clothing and disassemble it in the order of "exhaust first, then supply air" to prevent the spread of contaminants.
Primary filter: Check monthly. When dust accumulation is obvious, blow it with compressed air or replace it every 3 to 6 months.
Iv. Safety and Fault Handling
Key points of safety protection
Electrical safety: The equipment must be grounded. When maintaining, the power supply should be cut off. It is strictly forbidden to operate with power on.
Biosafety: After handling the pathogen, in-situ disinfection (such as high-temperature steam) is carried out on the interior of the laminar flow hood and the filter, and then the filter is replaced by professionals to prevent microbial leakage.
2. Common Fault Response
Insufficient air volume: Check the resistance of the filter. If it is normal, replace the fan capacitor or motor.
Abnormal noise: Abnormal noise from the fan may be due to worn bearings. Lubricating oil needs to be added or the bearings replaced. Airflow whistling is mostly caused by blocked air inlets. Cleaning the air intake screen will solve the problem.
The cleanliness does not meet the standard: Use a dust particle counter for detection. If the number of particles ≥0.5μm exceeds the standard (for example, > 3520 particles /m³ in the 100-level zone), immediately replace the high-efficiency filter and check whether the sealing gasket is aged and leaking air by the smoke method.
V. Industry Compliance and Special Scenarios
Pharmaceutical GMP compliance requirements
Regularly test for "suspended particles" and "settling bacteria" (settling bacteria in Grade A zone ≤1CFU/dish), record the data, and file it. For sterilization operations, keep the disinfection time, concentration, and the signature of the operator.
2. Precautions for Mobile laminar flow hoods
Avoid rain when used outdoors. The battery-powered type ensures that the backup power supply lasts for ≥4 hours. When moving, fix the filter compartment door to prevent vibration from damaging the components.
Summary
The daily application of laminar flow hoods should follow the principle of "prevention first and standardized operation". The entire process from equipment startup to maintenance must strictly follow the standard operating procedures (SOP). Especially in medical and pharmaceutical scenarios, regular training and the establishment of maintenance ledgers (recording filter replacement time, disinfection frequency, etc.) are necessary to ensure that the cleanliness level continuously meets the standards. Avoid pollution risks caused by management oversights.