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Comparison table between ISO cleanliness levels and Class 10, Class 100, Class 1,000 and Class 10,000

Correspondence between ISO Class 1-9 cleanliness level, particle concentration and traditional clean room level

Understand the ISO 14644-1 cleanliness grade standard, quickly check the common correspondence between Class 10, Class 100, Class 1,000, Class 10,000, Class 100,000 and ISO Class, providing reference for clean room design, FFU, EFU, HEPA, ULPA and other clean air equipment selection.

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What does cleanliness level mean?


Cleanliness classes are used to describe the concentration levels of suspended particles in the air of a clean room or clean area.

There are currently two sets of expressions commonly used in clean room projects:

ISO Class rating
According to standard systems such as ISO 14644-1, the concentration of airborne particles within the specified particle size range is used as the basis for cleanliness classification.

Traditionally called 'tenth level, hundredth level, thousandth level, ten thousand level, one hundred thousand level'
An expression of cleanroom class often used in engineering and industry communications in the past.

The two sets of names are often put together for comparison in engineering practice, but attention should be paid to:

Traditional terms such as 'Level 10, Level 100, Level 1,000, Level 10,000' and ISO Class are not exactly the same set of standard terms. The actual project should determine the cleanliness level based on applicable standards and test results.

ISO 14644-1:2015 stipulates the method for classifying cleanliness according to the concentration of suspended particles in the air, and sets corresponding limits for particle concentrations of different particle sizes.

Quick query of cleanliness level

Which ISO levels correspond to level ten, level one hundred, level one thousand, level ten thousand, and level one hundred thousand?


Traditional name for cleanlinessCommonly used ISO corresponding levels≥0.5 μm particle concentration limitunderstand quickly
Level 10ISO Class 4352 pieces/m³Higher cleanliness requirements
Level 100ISO Class 53,520 pieces/m³High cleanliness environment
Thousand levelISO Class 635,200 pieces/m³Clean production environment
Level 10,000ISO Class 7352,000 units/m³Common industrial clean environments
One hundred thousand levelISO Class 83,520,000 units/m³General clean production environment
Quick memory

Class 10→ ISO Class 4——Class 100→ ISO Class 5——Class 1000→ISO Class 6——Class 10,000→ISO Class 7——Class 100,000→ISO Class 8

Special attention is required:
Class 300,000 cannot simply correspond to a certain ISO Class.
ISO 14644-1 uses ISO Class 1 to ISO Class 9 for classification, and is not set according to the traditional 'Class 10, Class 100, Class 1,000, Class 10,000, Class 100,000, Class 300,000'.

ISO Class 1-9 Complete Cleanliness Level Table

ISO 14644-1 cleanliness grade particle concentration comparison table


ISO 14644-1:2015 classifies the concentration of suspended particles in the air that are greater than or equal to a specified particle size. Unit: particles/m³, that is, the number of particles per cubic meter of air.

ISO gradeTraditionally used names≥0.1 μm≥0.2 μm≥0.3 μm≥0.5 μm≥1.0 μm≥5.0 μm
ISO Class 1—102————
ISO Class 2—10024104——
ISO Class 3—1,000237102358—
ISO Class 4Level 1010,0002,3701,02035283—
ISO Class 5Level 100100,00023,70010,2003,52083229
ISO Class 6Thousand level1,000,000237,000102,00035,2008,320293
ISO Class 7Level 10,000———352,00083,2002,930
ISO Class 8One hundred thousand level———3,520,000832,00029,300
ISO Class 9————35,200,0008,320,000293,000
particles/m³, the number of particles per cubic meter of air.
The above particle concentration data corresponds to the cleanliness classification table of ISO 14644-1:2015. According to ISO official instructions, the standard uses the concentration of airborne particles for classification and takes into account the specified particle size in the range of 0.1 μm to 5 μm.
Form description:
'—' means that this particle size does not have a concentration limit applicable to this classification under the corresponding ISO level, which does not mean that such particles do not exist in the air.
The concentration in the ISO standard is the cumulative concentration . For example, 10,200 particles/m³ for ISO Class 5 at 0.3 μm refers to the number of particles greater than or equal to 0.3 μm.

What do you understand by ISO Class 1-9?

The smaller the ISO Class number, the higher the cleanliness requirements


ISO cleanliness levels range from Class 1 to Class 9.

Generally speaking:

ISO Class 1 → ISO Class 2 → ISO Class 3 represents increasingly stringent air cleanliness requirements.


and:

ISO Class 7 → ISO Class 8 → ISO Class 9 corresponds to a relatively loose cleanliness classification.


It can be simply understood as:

The smaller the ISO Class number is, the lower the allowed airborne particle concentration is and the higher the cleanliness requirements are.


For example:

The maximum allowable concentration of ISO Class 5 at particle size ≥0.5 μm is 3,520 particles/m³, while the corresponding value for ISO Class 7 is 352,000 particles/m³.


Therefore, the cleanliness requirements of ISO Class 5 are higher than those of ISO Class 7。

Class 10 clean room｜ISO Class 4

Class 10 clean room corresponds to ISO Class 4


'Class 10 clean rooms' in traditional industries usually correspond to ISO Class 4. ISO Class 4 mainly controls the concentration of fine suspended particles in the air, among which:


≥0.1 μm: 10,000 pieces/m³

≥0.2 μm: 2,370 pcs/m³

≥0.3 μm: 1,020 pcs/m³

≥0.5 μm: 352 pcs/m³

≥1.0 μm: 83 pieces/m³


Common applications


Level 10 clean environments can be used in production and local clean areas with higher requirements for air particle control, such as:


Semiconductor manufacturing

Precision electronics

Optical manufacturing

Precision instruments

Inside high cleanliness equipment

Local critical process areas


What purification equipment is needed for a Class 10 clean room?


This type of clean environment usually requires comprehensive considerations:


Number of FFU

HEPA or ULPA filter

Air supply volume

airflow organization

Return air system

room seal

personnel activities

Equipment produces dust


For local equipment clean areas, equipment-level air purification units such as EFU may also be used.

Class 100 clean room｜ISO Class 5

Class 100 clean room corresponds to ISO Class 5


The 'Class 100 clean room' often referred to in traditional industries usually corresponds to ISO Class 5.


ISO Class 5 main particle concentration limits include:


≥0.1 μm: 100,000 pieces/m³

≥0.2 μm: 23,700 pcs/m³

≥0.3 μm: 10,200 pcs/m³

≥0.5 μm: 3,520 pcs/m³

≥1.0 μm: 832 pcs/m³

≥5.0 μm: 29 pieces/m³


Common applications

Semiconductor production, electronic manufacturing

Precision assembly, pharmaceutical production

Laboratory, optical manufacturing

Precision equipment, clean operating area

Commonly used equipment in Class 100 clean rooms


Depending on the specific system design, you can use:

FFU

HEPA filter

ULPA filter

EFU

Clean workbench

Clean shed

Clean air conditioning system


Need to emphasize:

Class 100 clean rooms correspond to ISO Class 5, which does not mean that as long as the H14 filter is installed, it will definitely reach ISO Class 5.


The final cleanliness is also related to factors such as air supply volume, air exchange frequency, air flow organization, room sealing, equipment dust production and personnel activities.

Class 1000 clean room｜ISO Class 6

Class 1000 clean room corresponds to ISO Class 6


The traditional 'Class 1,000 clean room' usually corresponds to ISO Class 6.


The main particle concentration limits for ISO Class 6 include:


≥0.1 μm: 1,000,000 pieces/m³

≥0.2 μm: 237,000 pieces/m³

≥0.3 μm: 102,000 pieces/m³

≥0.5 μm: 35,200 pcs/m³

≥1.0 μm: 8,320 pcs/m³

≥5.0 μm: 293 pcs/m³


Common applications

Electronic manufacturing, precision manufacturing, laboratories, optical manufacturing

Precision assembly and some pharmaceutical production areas

Industrial clean production, thousand-level clean environment equipment


Common equipment includes:


FFU + HEPA filter


Can also be configured based on space and equipment requirements:


EFU + HEPA/ULPA


The actual configuration needs to be designed based on the room area, target air volume, equipment layout and air flow organization.

Class 10,000 clean room｜ISO Class 7

Class 10,000 clean room corresponds to ISO Class 7


The traditional 'Class 10,000 clean room' usually corresponds to ISO Class 7.


ISO Class 7 main controls:


≥0.5 μm: 352,000 pieces/m³

≥1.0 μm: 83,200 pcs/m³

≥5.0 μm: 2,930 pcs/m³


Common applications

Pharmaceutical production, electronics manufacturing, food production, cosmetics

Precision manufacturing, laboratories, industrial clean production


Common configurations of class 10,000 clean rooms

Depending on the project design, you can use:

FFU

HEPA filter

Clean air conditioning system

Fresh air system

Return air system

Clean shed

Local purification equipment

Class 100,000 clean room｜ISO Class 8

Class 100,000 clean room corresponds to ISO Class 8


The traditional 'class 100,000 clean room' usually corresponds to ISO Class 8.


ISO Class 8 main particle concentration limits include:


≥0.5 μm: 3,520,000 pieces/m³

≥1.0 μm: 832,000 pieces/m³

≥5.0 μm: 29,300 pcs/m³


Common applications

General clean production

Electronic manufacturing

food processing

cosmetic

Package

Pharmaceutical related production areas

Industrial clean environment


The specific application level still needs to be determined based on product technology, pollution control requirements and applicable standards.

Which ISO level corresponds to 300,000?

There is no direct corresponding ISO Class level for the 300,000-level clean room.


This is a question that users often search for.


There are names such as 'Class 100,000, Class 300,000' in traditional clean room projects, but ISO 14644-1 adopts the classification system from ISO Class 1 to ISO Class 9.


therefore:


Class 300,000 cannot simply be equated to a certain ISO Class.


In actual projects, if cleanliness classification needs to be carried out in accordance with ISO 14644-1, detection and judgment should be based on the actual particle concentration of the specified particle size, rather than direct conversion through the name 'Class 100,000/Class 300,000'.

Traditional cleanliness grade comparison table

How to convert between level ten, level one hundred, level one thousand, level ten thousand and level one hundred thousand?

Traditional name for cleanlinessCommonly used ISO corresponding levels≥0.5 μm maximum allowable concentration
Level 10ISO Class 4352 pieces/m³
Level 100ISO Class 53,520 pieces/m³
Thousand levelISO Class 635,200 pieces/m³
Level 10,000ISO Class 7352,000 units/m³
One hundred thousand levelISO Class 83,520,000 units/m³
Level 300,000No direct ISO correspondence—

Typical applications of ISO cleanliness levels

ISO Class 1-9 common application scenarios

ISO gradeCommonly used traditional namesTypical application directions
ISO Class 1-3No common traditional correspondenceHigh cleanliness precision manufacturing, key processes, local clean areas
ISO Class 4Level 10Semiconductors, precision electronics, optics, key processes
ISO Class 5Level 100Semiconductors, electronics, medicine, laboratories, precision assembly
ISO Class 6Thousand levelPrecision manufacturing, electronics, laboratory, optics
ISO Class 7Level 10,000Medicine, electronics, food, cosmetics, industrial clean production
ISO Class 8One hundred thousand levelGeneral clean production, electronics, food, packaging
ISO Class 9—Generally controlled environments and areas with relatively low cleanliness requirements
Notice:
There is no one-to-one correspondence between cleanliness levels and specific industries.
The same industry may have production areas with different ISO levels; the same ISO level may also be used in different industries.
The final grade requires a combination of:
Product process + Pollution control requirements + Number of personnel + Equipment dust production + Space layout + Air flow organization + Applicable standards
Determined comprehensively.

What needs to be considered to achieve ISO cleanliness levels?

Clean rooms are not just about filters

This is a very important point in clean room design.

Main factors affecting final cleanliness

factorImpact on cleanliness
HEPA/ULPA filterControlling particulate matter introduced into clean areas
FFU air volumeAffects air circulation and dilution capabilities in clean areas
ventilation rateImpact on pollutant emissions and air renewal
airflow organizationInfluence particulate matter diffusion and elimination
room sealReduce the entry of external polluted air
personnel activitiesPersonnel is an important source of particle pollution in clean rooms
Equipment produces dustProcess equipment may generate particulate contamination
Return air systemAffects air circulation and pollutant discharge
Differential pressure controlControl air flow between different areas
Operation managementAffects long-term cleanliness stability
Key points to understand

Filter efficiency ≠ final ISO class of clean room.
H13, H14, U15, U16, and U17 belong to the concept of filter efficiency levels.
ISO Class 1-9 belongs to the concept of air cleanliness classification in clean rooms or clean areas.
The two are related, but cannot be directly equal.

ISO cleanliness level andHEPA / ULPA Relationship

How to choose filters for different cleanliness requirements?

HEPA andULPA is an important part of the clean air system, but the filter grade needs to be selected based on the specific system。

target environmentCommon filter directionsCommon cleaning equipment
ISO Class 1-3High-efficiency filtration solutions such as ULPAULPA FFU, EFU, local purification equipment
ISO Class 4-5HEPA/ULPAFFU, EFU, clean equipment
ISO Class 6HEPAFFU, clean air conditioner, EFU
ISO Class 7HEPAFFU, clean air conditioner
ISO Class 8HEPAFFU, clean air conditioner
ISO Class 9Configure according to actual needsAir filtration and HVAC systems
Equipment produces dustProcess equipment may generate particulate contamination
Return air systemAffects air circulation and pollutant discharge
Differential pressure controlControl air flow between different areas
Operation managementAffects long-term cleanliness stability
Why can't I just choose the filter based on the ISO rating?
Because final cleanliness is affected by the entire air system.
For example, for an ISO Class 5 project, in addition to filters, you also need to consider:
Number of FFU, air volume, wind speed, number of air changes, air flow organization
Room height, return air method, equipment layout, number of personnel, process dust production

So the correct way is:
First determine the target cleanliness → then determine the air treatment method → ​​then select filters and FFU/EFU.

FFU, EFU and cleanliness levels

What is the difference between purification methods in clean rooms and inside equipment?

FFU: For clean room spaces


FFU , or Fan Filter Unit, usually integrates a fan with a HEPA/ULPA filter to provide filtered air to the clean room through top air supply.


Applies to:


Semiconductor clean room

Electronic manufacturing

medicine

laboratory

Precision manufacturing

Optics

Clean production of lithium batteries


EFU: For internal or local areas of the device


EFU , or Equipment Fan Filter Unit, is mainly used inside the equipment or in local clean areas.


Compared with ordinary clean rooms, EFUs tend to pay more attention to:


Installation height

Equipment internal space

Air volume

wind speed

filter size

Fan structure

Control method

Device interface


Therefore, in space-constrained applications such as semiconductor equipment, EFU often requires targeted design.

Aili Industrial products related to cleanliness levels

Configure clean air equipment according to different cleanliness requirements

Aili Industry provides a variety of products around clean air treatment, including:

productMain function
FFUProvide filtered circulating air supply to clean rooms
EFUProvide filtered air inside the equipment and local clean areas
BFUUsed for clean air supply and local purification
HEPA filterEfficiently filter fine particles in the air
ULPA filterAir filtration for higher filtration efficiency requirements
AC/EC/DC blowerProviding air power for clean air equipment
FFU group control systemCentralized control of FFU operating status and air volume
Clean workbenchProvide clean air to local operating areas
Clean shedBuild a local clean space
Air shower roomAuxiliary purification equipment before people or materials enter the clean area

Aili industrial clean air equipment solutions

Supporting capabilities from fans and motors to filters and control systems

After the cleanliness level is determined, the actual project implementation still needs to further solve:

Where does the air come from?

Through what filter?

At what air volume is it sent?

How to create stable airflow?

How to perform operation control?

This is also a part that needs to be considered comprehensively when selecting clean air equipment.

Aili Industry has long been engaged in the research and development and manufacturing of purification equipment and clean air products. It has a production base of approximately 30,000 square meters and has formed multi-link supporting production capabilities around fans, motors, control systems, sheet metal structures, filters and complete equipment.


Aili industrial product chain


AC/EC/DC fans→Control systems→Sheet metal structures→HEPA/ULPA filters→FFU/EFU/BFU→Clean air solutions

Among them, fans, motors and control systems can be matched according to the actual operating requirements of FFU, EFU and other equipment.

For different cleanliness levels and application scenarios, Aili Industry can base on:

ISO target cleanliness

Room area

Floor height

Target air volume

Filter level

filter size

Number of FFU

EFU installation space

Control method

Industry process requirements

Provide configuration and selection recommendations for clean air equipment.

Clean air equipment for different application industries

Serving a variety of clean production and air treatment applications

Aili Industry provides a variety of products around clean air treatment, including:

semiconductorElectronic manufacturingLithium batteryphotovoltaic
Wafer manufacturingElectronic assemblyBattery cell productionPhotovoltaic modules
Semiconductor equipmentSMTbattery equipmentPrecision manufacturing
medicinebiomedicinelaboratoryOptics
pharmaceutical productionBiopharmaceutical related environmentClean laboratoryOptical components
Clean productionExperimentation and R&Ddetection areaPrecision assembly
display panelPrecision manufacturingcosmeticfood
Panel manufacturingPrecision partsClean productionClean food production
display devicePrecision assemblyPackaging and fillingPackaging and processing

Ideas for selecting cleanliness levels

How to determine what level your clean room needs to reach?

Don't simply choose based on 'what grades are generally used in the same industry'.

It is recommended to determine in the following order:

The first step: clarify the product process

Determine whether the production process is susceptible to particle contamination.

Step 2: Clarify pollution control requirements

Determine the allowable particle contamination levels for your product and key control particle sizes.

Step 3: Determine the clean area

Not all areas must be of the same cleanliness level.

It can be divided according to the production process:

General area → clean area → high clean area → local key process area

Step 4: Determine ISO cleanliness level

Determine the target ISO Class based on actual testing requirements and applicable standards.

Step 5: Determine air purification equipment

Choose based on space and cleanliness requirements:

FFU / EFU / BFU / HEPA / ULPA / clean air conditioning / fresh air system, etc.

Step 6: Perform system matching

Final summary:

Air volume + air pressure + filter resistance + air flow organization + return air mode + control system

Determine the final plan.

Related product recommendations

Choose appropriate clean air equipment according to cleanliness level

FFU air purification unit

It is suitable for circulating air supply in clean rooms. It can be configured with HEPA or ULPA filters and selected according to the project air volume and control requirements.

Learn about FFU →

EFU equipment fan filter unit

Suitable for internal spaces of semiconductor equipment, electronic equipment and other equipment that require local clean air.

Learn about EFU →

HEPA high efficiency filter

It is used for high-efficiency particle filtration in clean air systems and can be selected according to H13, H14 and structural form.

Learn about HEPA filters →

ULPA ultra high efficiency filter

It is suitable for clean air environments with high requirements for air particle control. It can be selected according to U15, U16, U17 and other grades and actual system requirements.

Learn about ULPA filters→

FFU group control system

Used for centralized control of multiple FFU or EFU, corresponding solutions can be configured according to project scale and control requirements.

Learn about FFU group control system→

Aili industrial clean air solutions

Planning a cleanroom or purification facility?

Cleanliness classes are only the starting point for cleanroom design.

From ISO Class target determination, to HEPA/ULPA filter selection, to FFU, EFU, fans, control systems and airflow organization , system matching is required.

Aili Industry can provide: Focusing on clean rooms, clean areas inside equipment and local purification needs:

FFU + EFU + BFU + HEPA + ULPA + fan + motor + control system + product matching and selection support for related purification equipment.

Relying on multi-link production capabilities such as fans, motors, control systems, sheet metal structures, filters and purification equipment , Aili Industry can configure products according to the cleanliness goals, space conditions and equipment requirements of different projects.

Get cleaning equipment selection suggestions→

Learn about FFU/EFU options→

Inquire about HEPA/ULPA filters→

Regarding ISO cleanliness levels, you may also want to know

Frequently Asked Questions about ISO Cleanliness Levels

01. Which ISO level does a Class 100 clean room correspond to?

Class 100 clean rooms in traditional industries usually correspond to ISO Class 5.

02. Which ISO level does a Class 10 clean room correspond to?

Class 10 clean rooms in traditional industries usually correspond to ISO Class 4.

03. Which ISO level does a thousand-level clean room correspond to?

Class 1000 clean rooms in traditional industries usually correspond to ISO Class 6.

04. Which ISO level does a Class 10,000 clean room correspond to?

Class 10,000 clean rooms in traditional industries usually correspond to ISO Class 7.

05. Which ISO level corresponds to a 100,000-level clean room?

Class 100,000 clean rooms in traditional industries usually correspond to ISO Class 8.

06. Which ISO level does a 300,000-level clean room correspond to?

There is no ISO Class level that can be directly equivalent to the 300,000 level. Actual projects should be determined based on applicable standards and test results.

07. What is ISO Class 5 cleanliness?

ISO Class 5 is a higher cleanliness level and usually corresponds to Class 100 clean rooms in traditional projects.

08. How many levels does ISO Class 7 correspond to?

ISO Class 7 usually corresponds to the traditional Class 10,000 clean room.

09. How many levels does ISO Class 8 correspond to?

ISO Class 8 usually corresponds to traditional class 100,000 clean rooms

10. Is the smaller the ISO Class number, the cleaner it is?

yes. The smaller the ISO Class number is, the lower the allowed airborne particle concentration is and the higher the cleanliness requirements are.

11. Is Class 100 the same as ISO Class 5?

In common engineering correspondence relationships, Class 100 usually corresponds to ISO Class 5. However, the two come from different cleanliness expression systems, and actual projects should be confirmed according to applicable standards.

12. Is Class 10,000 the same as ISO Class 7?

In common engineering correspondence relationships, Class 10,000 usually corresponds to ISO Class 7. ISO Class 7 is classified according to the concentration of airborne particles.

13.What filters are required for ISO Class 5?

HEPA or ULPA filtration solutions can be selected based on the system design, while matching FFU, EFU or other air treatment equipment, and comprehensively considering air volume, resistance and air flow organization.

14. Which ISO Class level does the H13 filter correspond to?

There is no direct correspondence. H13 is the filter efficiency level, and ISO Class is the clean room air cleanliness level. The two are not the same classification system.

15. Is the H14 filter ISO Class 5?

no. H14 is a HEPA filter efficiency rating and is not directly equivalent to ISO Class 5.

16. Are ULPA filters always used in ISO Class 1?

no. ULPA can be used in environments with higher requirements for particle control, but whether ULPA is required and the final cleanliness level need to be designed according to the project.

17. Does an ISO Class 5 clean room require HEPA or ULPA?

It needs to be comprehensively judged based on project goals, air volume, filtration efficiency, air flow organization and process requirements, and cannot be determined directly based on ISO grade alone.

18. Can FFU be used in ISO Class 5 clean rooms?

Can. FFU is one of the commonly used air purification equipment in clean rooms, but the number of FFU, air volume, filter level and layout need to be determined according to the project design.

19. What is the difference between EFU and FFU?

FFU mainly serves clean room space, and EFU is mainly used inside equipment or local clean areas. EFU usually has more specific requirements for installation size, thickness, air volume and equipment interface.

20. Does a clean room only need to install a HEPA filter to achieve ISO Class 5?

no. The filter is only a part of the clean air system. Factors such as air volume, air exchange frequency, air flow organization, room sealing, equipment dust production, personnel activities and operation management also need to be considered.

21. What is the relationship between ISO cleanliness level and HEPA?

The ISO cleanliness level describes the cleanliness of the air in a clean area, and the HEPA describes the filtration efficiency level of the filter. HEPA can be used as a component of an air system that meets certain cleanliness requirements, but it cannot be directly equated with an ISO Class.

22. The higher the cleanliness level, the higher the filter level?

uncertain. The filter rating needs to match the overall air system. Filtration efficiency, air volume, resistance, equipment capabilities and actual process requirements all need to be considered comprehensively.

23. Can Aili Industries provide FFU and filters according to ISO grade?

Can. Aili Industrial can provide selection and matching suggestions for FFU, EFU, BFU, HEPA, ULPA and other products based on the target cleanliness, space size, air volume, filter level and installation requirements.

24. Is Class 100,000 the same as ISO Class 8?

In common engineering correspondence relationships, one hundred thousand levels usually correspond to ISO Class 8.

25.What industries is ISO Class 5 suitable for?

ISO Class 5 can be used in environments that have high requirements for air cleanliness, such as semiconductors, electronic manufacturing, medicine, laboratories, optics and precision manufacturing. The specific level needs to be determined according to process requirements.

26.What industries is ISO Class 7 suitable for?

ISO Class 7 can be used in a variety of environments such as medicine, electronics, food, cosmetics, laboratories and industrial clean production. The actual application should be determined according to the specific process and pollution control requirements.

Relevant knowledge recommendations

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  • Why does the same air volume produce different cleaning and protection effects?
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  • How does clean air supply coverage affect the number of equipment?
    Whether FFU uses HEPA or ULPA filters should be judged based on the target cleanliness level, process sensitivity and filter resistance. ULPA is more efficient, but the resistance may increase, and the fan operating point needs to be checked. This article explains efficiency correspondence, resistance verification, scenario selection, and organizes project verification data and on-site judgment points. Aili Industry has complete production capabilities in FFU complete machines and high-efficiency filters, and can provide HEPA and ULPA filter configuration solutions. Welcome to contact Aili Industry for project support.
  • How to determine the clean air supply volume based on actual working conditions?
    The clean air supply volume should be determined based on the protection range, air flow pattern, particle load, exhaust air and heat and humidity conditions. Area or cleanliness level can only provide partial information. Target operating conditions should be established first, and then system resistance and on-site verification can be used to check equipment capabilities.
  • Why does the measured average wind speed not mean that the air flow is uniform?
    The average wind speed only reflects the overall level of multiple readings and does not indicate that each location is close to the target. High and low wind speeds may cancel each other out, forming a qualified average value but retaining local weak protection zones, so the distribution and differences of measuring points should be viewed at the same time.
  • What particle problems can airflow short circuits cause?
    Air flow short circuit means that the supply air enters the return air or exhaust path before effectively passing through the protected area, which may result in sufficient total air volume but insufficient removal of workstation particles, slow recovery, or increased regional differences. It is necessary to check the actual path and not just the total air volume.
  • How to reduce local retention in non-unidirectional flow clean rooms?
    To reduce local retention in a non-unidirectional flow clean room, it is necessary to coordinate the distribution of air supply and return air, the placement of equipment and the location of pollution sources, so that air can cover and leave each workstation. Increasing the nominal air exchange rate will not necessarily resolve areas that are blocked or have shorted airflow.
  • How to identify lateral interference in a unidirectional flow area?
    Lateral disturbances in areas of unidirectional flow can be identified through airflow visualization, local wind direction and speed measurements, and operational correlation records. Focus on checking whether doorways, air-conditioning outlets, personnel movement, and equipment exhaust deflect the protective airflow or introduce background air.
  • How will the airflow change when the air supply distance increases?
    As the air supply distance increases, the airflow may change speed and direction due to diffusion, entrainment of background air and structural interference. The degree of change depends on the air outlet structure and environment. The wind speed on the air outlet surface cannot be directly regarded as the wind speed at the remote product location.
  • Will the height of the workbench front window affect the clean airflow?
    Workbench front window height affects local airflow by changing openings, external air exchange, and operating space. It should be operated in the usage position confirmed by the manufacturer. After adjusting the front window or adding a cover, the original protection conclusion cannot be used by default.
  • How does the size of the workbench match the actual operation?
    The size of the workbench surface should match the workpiece, fixtures, tools and operating paths, and leave space that does not block airflow. The usable area is not equal to the effective clean protection area. It should be selected based on the air outlet boundary and maintenance conditions, rather than just looking at the length and width of the desktop.
  • How to convert the clean area area into air supply demand?
    The area of ​​the clean area cannot alone determine the air supply volume. The one-way flow area can be estimated by the effective air supply area and the target average wind speed. The non-unidirectional flow area can be initially calculated based on the volume and ventilation demand. Finally, the pollution load, heat and air flow organization must be checked.
  • How to determine the protection area for a two-person clean workbench?
    The protected area of ​​a two-person clean workbench should be determined based on the effective air outlet range, the position of the workpiece and the actions of two people operating at the same time, rather than mechanically dividing the workbench in half. Mutual occlusion, material handover and external lateral airflow need to be checked and verified under representative actions.
  • Can an open workbench be used for hazardous materials operations?
    Ordinary open clean workbenches should not be used directly for hazardous material operations. Its clean air supply cannot limit the escape of hazardous materials by default; when infectious materials, harmful dust or steam are involved, the risk must be assessed first and corresponding engineering protection facilities selected.
  • What are the boundaries between clean workbenches and biological safety cabinets?
    The main purpose of the clean workbench is product protection, and the biological safety cabinet undertakes corresponding biological safety protection tasks according to its type and usage conditions. The two cannot be interchanged based only on appearance or cleanliness level. When selecting, the operational risks and objects that need to be protected should be confirmed first.
  • Does the clean workbench protect the product or the operator?
    Ordinary clean workbench mainly provides local particle protection of products or samples and cannot be regarded as a protective barrier for operators or the environment. If potentially infectious materials, hazardous chemicals or other hazardous materials are involved, appropriate protective equipment should be selected based on the risk.
  • How to choose between horizontal flow and vertical flow clean workbench?
    Horizontal flow and vertical flow clean workbench should be selected according to safe operating objects, workpiece shape, occlusion and action path. Both are typically used for product protection, and one should not be assumed to be capable of undertaking personal protection against hazardous materials just because of different airflow directions.
  • Can a clean workbench replace an entire clean room?
    The clean workbench mainly protects a limited work area and cannot directly replace the entire clean room. Its effect depends on the background environment, airflow boundaries and operating actions; when the workpiece is transported or temporarily stored outside the stage, it still requires corresponding air and material protection.
  • What are the initial resistance and final resistance used to judge?
    The initial resistance usually describes the pressure drop of a new filter under a specified air volume, and the final resistance is used to judge maintenance or replacement during the agreed use period. The final resistance is not the only life criterion. Damage, moisture, process risks and actual air supply capacity must also be considered.
  • Does increasing filter thickness definitely reduce resistance?
    Increasing filter thickness does not necessarily reduce resistance. The pressure drop is determined by the characteristics of the filter material, folding structure, filter area, air volume and internal support; the thickness is only a structural parameter, and the specific model data under the same working conditions should be used for comparison.
  • How does insufficient filter area affect fan selection?
    Insufficient filter area will increase the face velocity and resistance at the same air volume, and the fan may require higher pressure or speed to maintain flow. When selecting a model, you should first optimize the filter area and structure, and then check the fan curve. It is not advisable to simply compensate by increasing the motor.
  • What will be the impact if the wind speed facing the filter is too high?
    Too high a wind speed facing the filter may increase resistance, power consumption and noise, and cause the efficiency or sealing to withstand working conditions beyond the original confirmation range. It should be judged according to the performance and usage conditions of the specific model. It cannot be assumed that high wind speed is definitely conducive to cleanliness protection.
  • How does the rated air volume of the filter match the actual operating air volume?
    The rated air volume of the filter is used to describe its specified test or design conditions. The actual operating air volume should fall within the usage range confirmed by the manufacturer. When selecting a model, you need to check the efficiency, resistance, and fan operating point. You cannot determine replacement based on the same size.
  • How to read the test particle size in the filter efficiency report?
    The test particle size in the filter efficiency report should be read in conjunction with the adopted standard, test method and air volume. The fixed particle size results and the most penetrable particle size results are not the same caliber, and cannot be compared by just taking a percentage, nor can the filter material sample data be regarded as the finished product results.
  • Is ULPA mandatory for ISO Level 5 projects?
    ISO Level 5 projects do not always require the use of ULPA. Whether to use ULPA should be judged based on process particle size sensitivity, background load, equipment structure and verification requirements; the appropriate HEPA solution also needs to be confirmed through sealing, airflow and on-site concentration testing.
  • Does higher filtration efficiency necessarily lead to improved site ratings?
    Higher filtration efficiency does not necessarily improve the cleanliness level of the site. If the particles mainly come from downstream dust production, seal leakage or air flow backflow, upgrading the filter cannot solve the root cause; if the increase in resistance leads to a decrease in air volume, it may also weaken effective protection.
  • How to choose between H13, H14 and U15?
    H13, H14 and U15 should be selected based on the adopted filter classification standards, process particle control objectives and overall machine capabilities. The grade difference description specifies efficiency requirements under test conditions and is not a corresponding label for the room's ISO grade.
  • How do HEPA and ULPA match cleanliness goals?
    HEPA and ULPA should be selected based on process-sensitive particle size, allowable particle level, air volume and system resistance. Cleanliness level is one of the basis for configuration, but filters cannot be specified based on ISO numbers alone, nor should all locations be upgraded to ULPA.

ISO cleanliness level and clean air equipment

ISO cleanliness levels are used to describe the concentration levels of suspended particles in the air of clean rooms and clean areas. Class 10, Class 100, Class 1,000, Class 10,000 and Class 100,000 clean rooms in traditional industries usually correspond to ISO Class 4, ISO Class 5, ISO Class 6, ISO Class 7 and ISO Class 8 respectively in engineering practice.

The actual clean room design cannot select equipment based on only one grade name, but should be determined based on factors such as product technology, pollution control requirements, room area, number of air changes, air flow organization, personnel activities, and equipment dust production.

Aili Industry provides FFU, EFU, BFU, HEPA, ULPA, AC/EC/DC fans, control systems and related purification equipment , and can provide corresponding product selection and supporting solutions according to different cleanliness levels and application scenarios.

From the determination of cleanliness levels to the configuration of filters, FFU, EFU and control systems, Aili Industry provides multi-link product support for clean air applications.


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nancy@shdsx.com 13646258112

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.

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