1. Correspondence between liquid tank seal filter and clean room
Clean rooms are divided into different ISO classes (ISO 14644-1 standard) based on the concentration of suspended particles in the air, from ISO Class 1 (highest) to ISO Class 9 (lowest). Different levels of clean rooms have different requirements for air filtration systems, among which the installation and sealing method of the end high-efficiency filter is a key link.
The application of liquid tank sealed high-efficiency filters in clean rooms is mainly concentrated in high cleanliness areas of ISO level 5 and above. This is because as the cleanliness level increases, the tolerance for leakage at the filter installation frame becomes lower and lower. In clean rooms of ISO Class 6 and below, the impact of bypass leakage of ordinary sealing strip filters on the overall cleanliness is relatively controllable; however, in environments of ISO Class 5 and above, any tiny frame leakage may cause local cleanliness to exceed the standard.
2. Clean room ISO grade and filter selection comparison
ISO grade
Cleanliness requirements (≥0.5μm particles/m³)
Recommended filter types
Recommended sealing method
ISO class 1
≤20
ULPA (U15-U17)
Tank seal
ISO level 2
≤100
ULPA (U15-U17)
Tank seal
ISO level 3
≤1000
ULPA (U15-U16)
Tank seal
ISO class 4
≤10000
ULPA (U15) or H14
Tank seal
ISO class 5
≤100000
H14
Tank seal
ISO class 6
≤1000000
H13-H14
Sealing strip or tank
ISO class 7
≤3520000
H13
Sealing strip
ISO class 8
≤35200000
H13
Sealing strip
In clean rooms of ISO Class 5 and above, liquid tank seals are a more common configuration. ISO level 6 can be selected on demand, and ISO level 7 and below are usually sealed with rubber strips to meet the requirements.
3. Typical application scenarios of liquid tank seal filters
(1) Pharmaceutical GMP clean room
The GMP standards for the pharmaceutical industry classify clean rooms differently from international standards, and are usually divided into four levels: Class A, Class B, Class C and Class D:
Level A : high-risk operation area (such as aseptic filling, aseptic preparation). H14 or ULPA filter is required and tank seal is standard.
Level B : The background environment of the Level A area (such as a sterile production clean room). H14 filter is also required and the liquid tank is sealed.
Level C and D : non-sterile production or low-risk operating areas. H13-H14 filters can be used, and the sealing method can be selected according to specific requirements.
In Class A and Class B clean areas, the application of liquid tank seal filters is quite common. This is because the monitoring standards for suspended particles and microorganisms in clean rooms during GMP inspections are strict, and any frame leakage may cause monitoring data to exceed standards.
(2) Semiconductor and electronic manufacturing industry
The requirements for cleanliness in semiconductor chip manufacturing continue to increase as process nodes shrink:
Front-end processes such as photolithography and etching : usually require ISO 3-4 cleanliness and use ULPA (U15-U16) liquid tank sealing filters.
Diffusion, film deposition : ISO 4-5 cleanliness is usually required, and H14 or U15 liquid tank seal filters can be used.
Post-process packaging and testing : The cleanliness requirements are relatively low (ISO level 6-7), and H13-H14 rubber strips can be used to seal the filter.
In the semiconductor front-end process, the usage rate of liquid tank seal filter is high. This is because particle contamination on the wafer surface directly affects product yield, and any small leakage cannot be ignored.
(3) Hospitals and medical facilities
Areas in hospitals with the highest air cleanliness requirements include:
Laminar flow operating room : usually requires ISO level 5 cleanliness and uses H14 liquid tank seal filter. During the operation, the surgical area needs to maintain one-way flow, and the sealing performance of the filter installation is directly related to the postoperative infection rate.
ICU (Intensive Care Unit) : Some ICUs require ISO 6-7 cleanliness, H14 filters can be used, and the sealing method is selected according to specific requirements.
Hematology ward and burn ward : Patients with low immune function have high requirements for air cleanliness and are usually equipped with H14 liquid tank sealing filters.
(4) Biosafety laboratory
Biosafety laboratories (levels P3 and P4) have stricter requirements for exhaust systems. The exhaust filters must ensure that pathogenic microorganisms do not leak into the external environment:
P3 laboratory : The exhaust system usually uses H14 high-efficiency filter, and the liquid tank seal ensures that the exhaust duct does not leak.
P4 laboratory : The exhaust system adopts double HEPA filtration, and the two-stage filters are sealed with liquid tanks.
In these scenarios, the role of the liquid tank seal is not only to ensure internal cleanliness, but also to prevent the leakage of harmful biological aerosols.
(5) Precision manufacturing and scientific research facilities
Precision optical manufacturing : In the production environment of precision products such as optical lenses, lasers, and optical fibers, particulate matter is controlled below the micron level. ISO 4-5 clean rooms are usually equipped with liquid tank seal filters.
Medical device manufacturing : The production of implantable medical devices and high-precision diagnostic equipment is usually equipped with ISO Class 5 clean rooms and uses H14 liquid tank seal filters.
Nanomaterial research : Nanomaterial synthesis and characterization are extremely sensitive to particulate matter in the environment. It is usually equipped with an ISO 3-4 clean room and uses U15 and above ULPA liquid tank seal filters.
(6) Food and health product production
Links in the food and health care products industry that require higher levels of cleanliness include:
Aseptic filling line : The aseptic filling area for infant formula, liquid milk and other products is usually equipped with an ISO Class 5 clean room and uses an H14 liquid tank sealing filter.
Health product production workshop : According to GMP requirements, some health product production areas need to meet ISO 6-7 cleanliness levels. Filter types and sealing methods can be selected according to specific requirements.
4. Under what circumstances is the liquid tank seal necessary?
To determine whether a clean room needs to use a liquid tank seal filter, it is recommended to evaluate it from the following aspects:
Cleanliness level requirements : When the cleanliness level reaches ISO level 5 and above, it is recommended to use liquid tank seal. The higher the cleanliness level, the greater the necessity of liquid tank sealing.
Regulatory requirements : Pharmaceutical GMP Class A and Class B clean areas, biosafety P3 and P4 laboratories usually have clear requirements or industry practices to use liquid tank seals.
Process sensitivity : Semiconductor photolithography, aseptic filling, precision optical processing and other processes that are sensitive to particulate matter, even if the cleanliness level requirements are slightly lower, it is recommended to give priority to liquid tank sealing.
Leak detection requirements : If the project requires PAO leak detection for each filter after installation and the leakage rate standard is strict, the pass rate of the liquid tank seal filter will be higher.
5. Clean room application of Aili industrial liquid tank seal filter
Aili Industry has the following characteristics in the field of liquid tank sealed high-efficiency filters:
Complete coverage of efficiency levels
The efficiency grades of Aili industrial liquid tank seal filters cover the full series of H14 and ULPA U15, U16, and U17, meeting the needs of various clean rooms of ISO level 5 and above.
Liquid tank structural design
It adopts an anodized aluminum alloy frame, and the shape and size of the liquid tank are optimized to adapt to the knife-edge structure of mainstream clean room FFU and air-conditioning box bodies.
Matching sealant
Use polyurethane (PU) liquid tank sealant, which has good fluidity and curing characteristics to ensure that the sealant flows and fills all gaps after the knife edge is embedded.
Independent production of the entire industry chain
Aili Industry has been deeply involved in the field of purification equipment for more than 20 years, and has built a closed-loop industrial chain from fan research and development, control system development to high-efficiency filter production, with controllable quality in every link.
Test one by one
Each liquid tank sealing filter has been scanned and tested for leaks one by one before leaving the factory, and comes with a test report to meet the filter verifiability requirements of pharmaceutical, semiconductor and other industries.
If you want to learn more about the selection recommendations of liquid tank seal filters in specific clean room scenarios, you can contact the Aili Industrial Engineering Technical Team and provide the cleanliness level and installation conditions to obtain an adaptation plan.
HEPA installation should be carried out according to the airflow direction and installation drawing confirmed on site: first check the filter and frame, then clean the installation surface, press the seal evenly, and finally verify the air volume and seal under specified operating conditions.
When it is found that the HEPA installation direction is inconsistent with the product or box identification, the acceptance of this position should be suspended, the supplier's drawings and airflow arrows should be checked, and then adjusted according to the allowed installation method. Just because the filter fits into the frame doesn't mean the orientation is correct.
When purchasing HEPA, you should at least clarify the outer frame size, efficiency level and applicable standards, rated air volume, resistance, structure, sealing method, use environment and testing data requirements. The old filter element replacement project also requires installation frame and disassembly and assembly path information.
Differences in high-efficiency filter quotations may come from efficiency levels, filter materials, structural dimensions, resistance requirements, sealing methods, detection range and order quantity. When comparing prices, you should first confirm whether each quotation corresponds to the same technical conditions.
The installation quality of the liquid tank high-efficiency filter directly affects the sealing effect and cleanliness. Before installation, it is necessary to check that the appearance of the filter is not deformed or damaged, that the liquid tank is intact, and that the box knife edge is flat and free of burrs. During installation, pay attention to controlling the injection amount of sealant to 70%-80% of the depth of the liquid tank, and inject glue evenly and continuously along the periphery of the liquid tank. The filter must be vertically embedded in the knife edge and pushed into place; after installation, it is recommended to conduct a visual inspection, a PAO leak test and an initial resistance record. Common problems include sealant overflow (too much glue), insufficient sealant (too little glue), difficulty in pushing the filter (skew or size mismatch), and PAO leak detection frame leakage (insufficient insertion depth or missing glue). Aili industrial liquid tank high-efficiency filter is provided with polyurethane sealant and installation guidance materials, and the engineering technical team can provide installation technical guidance support.
The liquid tank high-efficiency filter and the ordinary non-partition high-efficiency filter belong to the non-partition filter category. The core difference lies in the frame structure and sealing method. The liquid tank filter frame has a liquid tank groove, and liquid sealant is injected to achieve sealing. The sealant flows and fills all irregular gaps. It has high long-term reliability and is suitable for ISO class 5 and above clean rooms. Ordinary filters without partitions are sealed by sealing tape extrusion, with a simple structure and low cost, and are suitable for ISO class 5 and below scenarios. The filtration area of the liquid tank filter of the same size is slightly smaller (about 5%-10% less), the price is higher, and the replacement operation is cleaner. When selecting, a comprehensive judgment must be made based on the cleanliness level, leak detection requirements, replacement frequency and budget. Aili Industrial produces two types of filters at the same time, with efficiency levels covering H13, H14 and U15-U17. Each unit has been tested and a test report has been issued.
The liquid tank high-efficiency filter and the ordinary non-partition high-efficiency filter belong to the non-partition filter category. The core difference lies in the frame structure and sealing method. The liquid tank filter frame has a liquid tank groove, which is sealed by injecting liquid sealant. The sealant flows and fills all irregular gaps. It has high long-term reliability and is suitable for ISO class 5 and above clean rooms. Ordinary partition-less filters are sealed by sealing strips. The structure is simple and the cost is low. It is suitable for ISO class 5 and below scenarios. The filtration area of the liquid tank filter of the same size is slightly smaller (about 5%-10% less), the price is higher, and the replacement operation is cleaner. When selecting, a comprehensive judgment must be made based on the cleanliness level, leak detection requirements, replacement frequency and budget. Aili Industrial produces two types of filters at the same time, with efficiency levels covering H13, H14 and U15-U17. Each unit has been tested and a test report has been issued.
V-type high-efficiency filters can reach H13 and H14 levels of EN1822:2009 standards. The total MPPS efficiency of H13 is ≥99.95%, and the local penetration rate is ≤0.25%; the total MPPS efficiency of H14 is ≥99.995%, and the local penetration rate is ≤0.025%. H13 is suitable for ISO7-8 clean rooms, electronic assembly, food processing and other scenarios; H14 is suitable for ISO5-6 clean rooms, pharmaceutical GMP, hospital operating rooms, semiconductor manufacturing and other key places. The V-shaped filter is designed with a V-shaped structure and can achieve large air volume carrying and controllable resistance in both H13 and H14 grades. When selecting, a comprehensive judgment must be made based on cleanliness level requirements, industry specifications and system air volume. Aili industrial V-type high-efficiency filters strictly comply with the EN1822 standard, and the efficiency levels cover H13 and H14. H14-level products are scanned and tested for leaks one by one, and test reports are provided.
The initial resistance is the pressure difference value of the new V-type high-efficiency filter under the rated air volume, in Pa, which is the basic parameter for selection, operation and maintenance. The initial resistance of V-type filter H13 grade is usually ≤200Pa, and the initial resistance of H14 grade is usually ≤250Pa. Under the same conditions, the resistance of H14 is slightly higher than H13. The initial resistance is used for fan head calculation and energy consumption assessment during selection, and is used as a basis for replacement judgment during operation - the final resistance is usually set to twice the initial resistance. When the actual measured initial resistance is high, it is necessary to check whether the actual air volume matches the rated air volume, and check whether the installation is standardized. Initial resistance is an important parameter affecting operating costs. Aili Industrial V-type high-efficiency filter is designed with low resistance. The initial resistance of H13 is ≤200Pa, and the initial resistance of H14 is ≤250Pa. Each unit has been tested for resistance and a test report has been issued.
V-type high-efficiency filters are suitable for both constant air volume (CAV) and variable air volume (VAV) HVAC systems. The air volume of the CAV system is constant and the working conditions are stable. The V-shaped filter can take advantage of low resistance and high efficiency when selected according to the designed air volume. The air volume of the VAV system is dynamically adjusted as the load changes. The V-shaped filter has a strong structure and good adaptability to wide wind speeds. The wind speed can reach 2.5m/s under the initial resistance condition of 250Pa, adapting to wind speed fluctuation conditions. When selecting the VAV system, the maximum design air volume should be used as the basis, and a 20%-30% fan pressure head margin should be reserved. It is also recommended to configure a differential pressure transmitter to monitor the resistance in real time. V-type filter efficiency grade (H13/H14) does not affect the adaptability of the air volume system. Aili Industrial V-type high-efficiency filter has a solid structure, rated air volume covering 2400-4200m³/h, and is suitable for CAV and VAV systems. Each unit has been scanned and tested for leaks one by one and a test report has been issued.
The selection of large air volume V-type high-efficiency filter requires comprehensive consideration of four core parameters: rated air volume, overall size, initial resistance and efficiency level. Common specifications include rated air volume covering 850-4200m³/h, external dimensions ranging from 287×592×292mm to 1220×610×292mm, and initial resistance as low as ≤200Pa. The selection steps include calculating the total air volume of the system, determining the air volume requirement of a single unit, selecting the overall dimensions according to the parameter table, checking the installation space (especially the depth direction, the standard is 292mm), selecting the efficiency level (H13 or H14), checking the initial resistance and evaluating the replacement cycle. It is recommended to reserve 10%-20% air volume margin when selecting a model to avoid neglecting the depth size, the impact of efficiency level on air volume, and the difference between initial resistance and final resistance. Aili Industrial provides a variety of dimensions and V-shaped configurations, with rated air volume covering 850-4200m³/h. It strictly complies with the EN1822 standard. Each unit has been scanned and tested for leaks one by one and a test report has been issued.
The V-type high-efficiency filter is arranged in a V-shape with multiple filter elements without partitions, which increases the filtration area to 3-5 times that of ordinary flat-plate filters under the same external dimensions. Its core principle is to expand the filter material from a two-dimensional plane to a three-dimensional space, making full use of the depth direction of the frame. The increased filtration area brings practical advantages such as low resistance (initial resistance can be as low as ≤200Pa), large air volume (rated air volume can reach 2400-4200m³/h), high dust holding capacity and reduced number of filters. V-type filters are suitable for large air volume scenarios in limited spaces such as the end of air-conditioning boxes, compact HVAC systems, return air ducts in clean factories, and upgrades of existing systems. When selecting, you need to confirm the installation depth, select a V-shaped configuration according to the air volume, and check the system resistance. Aili industrial V-type high-efficiency filters strictly comply with the EN1822 standard and are available in 3V, 4V, and 5V specifications. Each unit has been scanned and tested for leaks one by one and a test report has been issued.
V-Bank high-efficiency filter (V-type combined high-efficiency filter) uses multiple filter elements without partitions to form a V-shaped structure. The rated air volume can reach 2400-4200m³/h. It is suitable for constant air volume (CAV) and variable air volume (VAV) HVAC systems. Typical application scenarios include hospital operating rooms and ICUs, pharmaceutical GMP workshops, electronic and semiconductor clean workshops, food processing plants, data centers, hotels and schools and other commercial buildings, as well as industrial ventilation facilities such as power plants. V-Bank filters can be used as high-efficiency filtration or ULPA pre-protection at the end of air conditioning boxes in HVAC systems. They have technical advantages such as large air volume carrying capacity, low operating resistance, high dust holding capacity, and saving installation space. Aili Industrial V-Bank high-efficiency filters strictly comply with EN1822 standards, with efficiency levels covering H13 and H14, adapting to the needs of various HVAC air treatment systems. Each unit has been scanned and tested for leaks one by one and a test report has been issued.
The V-type partitionless high-efficiency filter uses multiple partition-less filter elements to form a V-shaped structure. The filtration area can reach 3-5 times that of ordinary filters, the rated air volume can reach 2400-4200m³/h, and the initial resistance can be as low as ≤200Pa. In large air volume systems, compared with ordinary high-efficiency filters, V-type filters have the advantages of reducing the number of filters, saving installation space, reducing installation costs, reducing operating energy consumption, and extending the replacement cycle. The efficiency level covers H13 and H14, and is suitable for large air volume scenarios such as terminal filtration of air-conditioning boxes, electronic semiconductors, pharmaceuticals and medical care, and power plants. When selecting, you need to pay attention to parameters such as rated air volume, initial resistance, efficiency level, and overall dimensions. Aili Industrial V-type partitionless high-efficiency filter strictly complies with the EN1822 standard and provides large air volume design, low resistance and high dust holding capacity, optional multi-material frames and unit-by-unit inspection services.
The V-type high-efficiency filter (V-Bank) uses multiple filter elements without partitions to form a V-shaped structure. The filtration area can reach 3-5 times that of ordinary filters. The designed air volume is more than 2 times higher than that of high-efficiency filters with partitions. The initial resistance can be as low as ≤200Pa. Compared with ordinary high-efficiency filters, V-type filters require fewer installations, smaller installation space, lower operating resistance, higher dust holding capacity and longer service life under the same air volume. The efficiency level covers H13 and H14, and is mainly used in scenarios such as terminal filtration of air-conditioning boxes, large air volume HVAC systems, electronic semiconductors, pharmaceuticals, medical and power plants. Aili industrial V-type high-efficiency filters strictly comply with the EN1822 standard, provide multiple specifications and are tested one by one, and support customized production.
The thickness (50mm, 70mm, 90mm, 120mm) and filter area of the high-efficiency filter without partitions directly affect the air volume carrying capacity, initial pressure difference, dust holding capacity and service life. 70mm is the standard configuration of FFU, which strikes a balance between space occupation and performance; 90mm and 120mm are suitable for equipment with ample space such as air-conditioning boxes, with larger filter area and longer replacement cycle. When selecting, a comprehensive judgment must be made based on the size of the installation space, system air volume, fan head margin and full life cycle cost. If space allows, choosing a thicker filter, lower energy consumption and longer replacement intervals can usually pay back the cost difference within 1-2 years. Aili Industrial provides multiple thickness specifications of 50-120mm and non-standard customization services. Each unit is scanned and tested for leaks one by one and a test report is issued. The engineering and technical team can assist in air volume calculation and resistance calculation.
The partition-less high-efficiency filter uses ultra-fine glass fiber filter paper and hot-melt adhesive line separation technology, and can cover the full range of efficiency levels of H13, H14 and ULPA U15, U16, and U17. According to the EN1822 standard, H13 efficiency ≥ 99.95%, H14 ≥ 99.995%, U15 ≥ 99.9995%, U16 ≥ 99.99995%, U17 ≥ 99.999995%. Different levels correspond to different cleanliness requirements - H13 is suitable for ISO 7-8 clean rooms, H14 is suitable for ISO 5-6 clean rooms, and the local penetration rates of H13 and H14 differ by ten times. ULPA conducts efficiency assessments in the particle size range of 0.1-0.2μm and is suitable for high cleanliness environments of ISO level 4 and above. When selecting a model, a comprehensive balance must be made based on the cleanliness level, industry standards, system air volume and budget. Aili Industrial has independent production capabilities across the entire industry chain and strictly follows the EN1822 standard. Each filter is scanned and tested for leaks one by one and a test report is provided. It supports full series customization of H13, H14 and U15-U17.
When the installation space of FFU, EFU, clean shed or other clean equipment is limited, high-efficiency filters without partitions can be considered. The partition-less structure uses glue lines to fix the fold distance of the filter material, and has a certain design space in terms of filter thickness, filter area and internal structure. The actual selection should not only focus on the thickness of the filter, but also need to comprehensively consider the filtration efficiency, target air volume, initial resistance, fan static pressure, sealing method and later replacement space. Aili Industry can match the specifications of high-efficiency filters without partitions based on the equipment installation dimensions and operating parameters.
Partitionless high-efficiency filters can be used in clean environments such as semiconductors, electronic manufacturing, photovoltaics, pharmaceuticals, laboratories and precision manufacturing according to different specifications, and are often used in conjunction with FFU, EFU, clean sheds and clean room terminal air supply equipment. Different applications have different requirements for filtration efficiency, air volume, resistance, size, thickness and sealing methods, so selection needs to be based on specific equipment and clean environments. Aili Industry can match the specifications of high-efficiency filters without partitions based on industry applications, equipment structures and project parameters.
High-efficiency filters without partitions usually adopt filter material folding, glue line separation and outer frame sealing structure, without using traditional paper partitions or aluminum partitions. Its specifications mainly include overall dimensions, thickness, filtration efficiency, air volume, initial resistance, outer frame material and sealing method, etc. When used in FFU, EFU, clean sheds and clean room terminal air supply equipment, it needs to be matched based on the installation space, fan performance and target air volume. Aili Industry can provide corresponding specifications and configurations of high-efficiency filters without partitions based on equipment size, air volume, filtration efficiency and usage environment.
Aili Industrial develops and manufactures
FFU, EFU, HEPA/ULPA air filters, high-efficiency air supply vents, fan boxes and other clean air equipment. Relying on motors, fans, control systems, filters and complete machine supporting capabilities, we provide selection and customization support for clean room and production equipment projects.
