Here is a set of methods for inspecting the leak of ultra-clean workbench high-efficiency filters that are applicable to both pharmaceutical factories and laboratories, and can be directly incorporated into the SOP. The focus is on the most commonly used and compliant PAO method for leak detection, which is simple and easy to understand and can be performed on-site. I. Applicable Standards Commonly used in the pharmaceutical / GMP field: ISO 14644-3, GB/T 25915 Core: Check whether the high-efficiency filter, the filter paper itself, and the frame seal are leaking II. Most Common Method: PAO Aerosol Leak Detection Method 1. Required Tools PAO aerosol generator Aerosol photometer (leak detector) Clean gloves, alcohol 2. Basic Principle Upstream dust generation: Introduce PAO aerosol to the inlet side of the high-efficiency filter Downstream scanning: Use the photometer to scan the outlet side Exceeding the standard → Leakage is determined 3. Operating Steps (Special for Ultra-clean Workstations) Start the ultra-clean fan and let it run for ≥ 10 minutes. The airflow should be stable. Upstream dust generation: Place the nozzle of the PAO generator on the inlet side of the high-efficiency filter (generally on the top / rear), allowing the aerosol to evenly enter

Determining whether the pre-filter (primary or secondary) needs to be replaced is quite simple. Just remember the 4 criteria and you can make the decision by observing and testing on-site without having to guess. 1. Check the pressure difference (the most accurate and standard method) This is the most common method used in HVAC and cleanroom systems: When installing, record the initial pressure difference. If the pressure difference reaches twice the initial pressure difference, it’s time to replace it. Common experience values (for quick judgment only): Primary filter: Final resistance 90-150 Pa Secondary filter: Final resistance 150-250 Pa As long as the pressure difference reaches this level, regardless of whether it’s dirty or not, it is recommended to replace it. Otherwise, the lifespan of the subsequent high-efficiency filter will be significantly shortened. 2. Check the appearance (the most intuitive) Without using instruments, you can also make the judgment: The filter material is obviously blackened, yellowed, or covered with dust The filter screen is deformed, collapsed, or bulging The frame, sealing area has chips, damage, or air leakage The surface has mold spots, water stains, or corrosion If any of these conditions occur, replace it immediately. 3. Feel the wind speed

I. Installation Precautions (Key Points) Location Selection Install it within the partition between the clean area and the non-clean area. Avoid placing it close to dust-producing, damp, or highly-vibrating equipment. Reserve maintenance space to facilitate the replacement of high-efficiency filters, lamps, and wiring in the future. Wall Hole Opening and Fixation The opening size should be slightly larger than the outer frame of the transfer window. Leave a 10-20mm gap around it. Fix it firmly with expansion bolts. The box must be level and vertical to avoid door deformation and poor closure. Sealing is of utmost importance (core for preventing contamination) The gap between the box and the wall must be fully sealed with sealant / foaming agent + sealant. There should be no gaps or holes. The door sealing strip must be complete, undamaged, and without distortion. It should be tightly pressed without light leakage after closing. Interlock Function Must Be Adjusted Correctly Electronic / Mechanical Interlock: When one door is opened, the other door must be absolutely unable to open. After powering on, repeatedly test: Door A opens → Door B locked; Door A closed → Door B can be opened. Electrical Installation Power Supply: AC220V/50Hz, independent socket

To extend the lifespan of the paper frame high-efficiency filter, the key lies in one thing: avoid allowing large particles and dust to directly block the high-efficiency section, and prevent dirt from reaching it in advance. Here are the most practical and immediately applicable methods in the field: 1. Front-end filtration setup (most crucial) It must be combined with a primary filter + a secondary filter + a tertiary filter Fresh air → Primary filter → Secondary filter → High-efficiency filter The primary and secondary filters should be replaced regularly, not waiting until they are completely clogged Primary filter: replace or clean every 1 to 3 months Secondary filter: replace every 3 to 6 months A well-set front-end filtration system can directly extend the lifespan of the high-efficiency filter by 30% to 100% 2. Control environmental humidity and temperature The paper frame is afraid of moisture and water. If the humidity remains above 80% for a long time, it is prone to deformation, warping, and air leakage. Avoid direct contact of condensation water, spray, and water leakage with the filter The environmental temperature should be as low as possible, below 60℃. High temperatures will cause the paper frame to soften

Below is a detailed list of the most crucial, easily overlooked, and directly affecting the lifespan and cleaning efficiency aspects when installing an efficient filter in a manual double-door or shower room, specifically for this purpose. It is practical and can be directly followed: 1. Pre-installation precautions Make sure the direction is absolutely correct and the filter cannot be installed backwards. The efficient filter has arrow markings, and the arrow must be in the same direction as the airflow (in a shower room, it usually blows from the outside to the inside). Installing it backwards will result in high resistance, easy clogging, sealing failure, and a halved lifespan. Clean the installation frame and box Before installation, wipe the static pressure box, installation slot, and sealing strip position with a dust-free cloth. There should be no dust or debris. Dust can cause poor sealing and air leakage. Do not touch or squeeze the filter paper with your hands. Finger oil and sweat can damage the filter paper structure, causing local blockage or leakage. Only grasp the metal frame when moving, do not pinch the filter paper. 2. Sealing section (most critical) The sealing strip must be complete, without fractures, and not

Based on the automatic double-door cargo shower room conditions you have been asking about, here is the most practical and industry-standard lifespan conclusion for you: 1. General usage environment (most factories) Electronic, food, ordinary clean workshops, little dust Used for 8 to 12 hours per day, normal maintenance Efficient filter lifespan: 1 to 2 years 2. High dust, high usage frequency environment Raw material workshop, packaging workshop, large dust, frequent transfer 24-hour operation or extremely high usage frequency Lifespan: 6 to 12 months 3. Pharmaceutical / GMP sterile clean area Strict compliance requirements, not just about whether it is blocked Suggested lifespan: No more than 12 to 18 months for mandatory assessment and replacement 4. What truly determines whether to replace or not is not the time As long as any of the following occurs, even if only used for 1 month, it should be replaced: Pressure difference exceeds the initial pressure difference by more than 1.5 times PAO leak detection or particle scanning shows leakage The air outlet of the shower room has significantly reduced wind speed Filter material is damaged, damp, or moldy 5. Remember in one sentence Maintain well, less dust: 1 to 2 years High dust,

Paper-frame high-efficiency filters (HEPA) are high-performance air purification devices with a paper or composite paperboard frame and glass fiber filter paper as the filter material. They are mainly used to capture extremely fine particles (such as dust, smoke, and bacteria) larger than 0.3 μm. They are cost-effective, lightweight, and easy to install and replace, making them the mainstream choice for end-of-line filtration in clean environments. 1. Core application fields 1. Electronics and semiconductor manufacturing (main application) Used to control air dust and ensure product yield. Scenarios: Wafer lithography / etching rooms, chip packaging and testing workshops, LCD/OLED factories, hard disk / magnetic head workshops. Grade: ISO Class 4-7 clean rooms, commonly H13-H14 grades. Installation: FFU (fan-filter unit), clean room shelters, laminar flow hoods at the end. 2. Biopharmaceuticals and hospitals (sterile / high hygiene requirements) Pharmaceuticals: GMP A/B sterile filling lines, raw material drug workshops, laboratories. Medical: Operating rooms, ICUs, isolation wards, sterile dressing rooms, biosafety cabinets. Function: Intercept bacterial and virus aerosols to prevent cross-infection. 3. Food and cosmetics processing Scenarios: Baking, beverages, health supplements, cosmetics sterile filling / packaging workshops. Function: Filter air-borne microorganisms and dust to avoid product contamination. 4. Precision instruments and aerospace Scenarios: Optical lens

The normal service life of paper-frame high-efficiency filters is mostly between 6 and 12 months. In reality, there will be significant differences depending on the dirtiness of the usage environment. Here is a practical and commonly used reference range for you: 1. General service life reference Clean rooms, electronics factories, operating rooms, and pharmaceutical workshops have relatively clean environments and are protected by primary and intermediate filters → 6 to 12 months Spray workshops, woodworking workshops, cement plants, garbage stations, etc., with large amounts of dust and heavy oil stains → 3 to 6 months, or even shorter Office buildings, shopping malls, and ordinary central air conditioning environments have medium levels of dust → 9 to 12 months Home / commercial air purifiers → 8 to 12 months 2. Criteria for determining when to replace (more accurate than time) Generally, we do not strictly adhere to a fixed time. Look at these two points: The final resistance reaches about twice the initial resistance (usually when it reaches 400 to 450 Pa, it must be replaced) The air volume becomes significantly smaller, the air outlet is weak, or the cleanliness does not meet the standard Paper-frame high-efficiency filters cannot be cleaned

I. Standardize data collection and ensure accuracy from the source The detection instruments must be calibrated regularly Pressure differential meters, particle counters, temperature and humidity meters, etc. should be within the valid calibration period. The calibration certificate number should be recorded in the ledger to avoid errors in data caused by instrument inaccuracies. Unify data reading standards Ensure that the line of sight for pressure differential readings is perpendicular to the dial and be precise to two decimal places; for example, measure the temperature and air volume of the fan using a unified method to prevent human reading errors. Double-check critical data by two people For important data such as the final resistance of the high-efficiency filter and cleanliness testing, two people should read and confirm separately. If there is inconsistency, immediately re-measure. II. Implement on-site immediate recording to eliminate memory errors Adhere to recording while operating, fill in immediately after measuring the pressure differential and completing the cleaning. Prohibit recalling and supplementing after the fact. Avoid vague descriptions. All states should be quantified and filled in, for example, write “Pressure differential 280Pa, approaching the initial value by 1.5 times”, rather than simply writing “Normal”. III. Standardize record filling to

The retention period for the daily maintenance records of the air supply ceiling ( laminar flow ceiling ) depends mainly on industry regulations, product/project lifecycle, and the risk level of the clean area. There is no uniform “one-size-fits-all” figure across the country, but there are clear compliance guidelines in mainstream industries such as pharmaceuticals (GMP), medical devices, electronics, and food. 1. Pharmaceutical Industry (GMP): The strictest and most explicit Bottom line requirement: At least keep for 1 year after the expiration of the product Daily maintenance records (pressure difference, air velocity, cleaning, filter replacement, leak detection): At least 5 years (industry standard, default standard for audits) Sterile drugs, high-risk products (A/B class areas): Suggested to keep ≥ 10 years (or until the product is withdrawn) Key records (efficiency filter leak detection, replacement, verification): Long-term preservation (entire equipment lifecycle) 2. Medical Device Industry (GMP / Medical Device Production Specifications) Maintenance records for purification systems and air supply ceilings: At least 5 years Involving sterile, implantable: Suggested ≥ 5 years, or 3 years after product launch 3. Electronics Semiconductor / Precision Manufacturing (ISO 14644) Daily maintenance, particle monitoring, filter replacement records: At least 3 years Key process areas (such as 100-level /

Based on the paper partition / aluminum partition you previously asked about, I have compiled a set of filter selection steps that can be directly implemented in the project. This selection process takes into account various factors such as working conditions, cleanliness level, environment, and cost, and is very practical in engineering. 1. First, determine these 4 core conditions: Cleanliness level requirements For general ventilation and comfort air conditioning: Medium efficiency is sufficient, and high efficiency is usually not necessary. For 100,000-level and 10,000-level clean rooms: Initial efficiency + medium efficiency + high efficiency is required. For 100-level, 1,000-level: High efficiency / ultra-high efficiency filters must be used. Environmental temperature and humidity Normal temperature and dryness: Paper partition can be used for high efficiency. High temperature, high humidity, and steam sterilization: Aluminum partition must be used for high efficiency. Presence of corrosive and chemical gases For ordinary air: Paper partition is feasible. For acids, bases, and organic solvents: Only aluminum partition + anti-corrosion frame can be selected. Vibration and installation conditions Ceiling, quiet units: Paper partition can be used. Near the fan, high vibration: Aluminum partition should be preferred, as it is less prone to damage. 2. Select directly based

Based on the scenario of your negative pressure weighing chamber, I have clearly listed the differences and reasons for the replacement cycles of different types of high-efficiency filters, while also differentiating by structure, material, and application scenario, to facilitate your direct use in equipment management: 1. Classified by filtration efficiency grade Type Applicable scenarios Regular replacement cycle Reasons for cycle differences H13 High-efficiency Filter Negative pressure weighing room, normal clean area air supply 12 ~ 24 months The filter paper has an appropriate pore size and a moderate dust holding capacity, and is a mainstream configuration for the weighing chamber. H14 Ultra-High Efficiency Filter Highly active, sterile, and highly precise weighing 10 ~ 18 months Higher filtration accuracy, denser filter paper, faster increase in wind resistance, prone to clogging II. Classification by Filter Material Conventional Glass Fiber High-Efficiency Filter Period: 12-24 months Features: Large dust holding capacity, suitable for dry dust environments, high cost performance PTFE Coated High-Efficiency Filter Period: 8-12 months Features: Dust adheres only to the surface, not easily penetrable, but the surface is prone to accumulate dust and block, and the resistance rises rapidly; resistant to acid and alkali, resistant to humidity, suitable for frequent disinfection scenarios