Can the same clean room be marked with multiple ISO classes?

Direct answer: Classes can be declared separately for different states or clearly defined clean areas, but each declaration must indicate the range, particle size and operating conditions.

This approach is very common in actual projects. There are background environments in a room, and there are key workstations that are more sensitive to particles; or the same area behaves differently in static and dynamic conditions. Labeling these different situations separately is more accurate than covering them all with one level.

But multi-level annotations cannot be written at will. If the scope is unclear, or test records and statements do not match, problems will arise in acceptance and subsequent management.

Why are there multiple levels of demand?

The same clean room needs to be marked with multiple grades, usually from several situations.

Background areas and local protected areas . The entire room is designed according to ISO 7, but a certain assembly station or equipment opening requires ISO 5 level partial protection. The background environment is maintained by room air supply, and key locations are enhanced by local air supply units.

Different process areas . In the same factory, particle control requirements may be different between precision assembly areas and general operating areas. Declaring levels separately by region is more in line with actual needs than a unified upgrade.

Static and dynamic states . The results of static and dynamic testing can differ significantly. Some items need to be declared in two states separately, rather than just taking one result.

Equipment interior and room environment . The microenvironment inside the equipment cavity and the environment of the room where the equipment is located have different control objectives and evaluation methods and should be marked separately.

These situations are all reasonable. The key is that each statement must have corresponding test conditions and scope.

Area boundaries should be clearly stated on drawings

The first step in multi-level labeling is to clearly mark the areas corresponding to each level on the drawing.

Supply air boundary . Indicate which air outlets or FFUs serve this area and where the airflow coverage goes. The boundaries of local protected areas cannot be drawn based on feelings alone, but must correspond to the actual airflow organization.

Return air path . Return air location and direction can affect airflow exchange between zones. If two levels of areas share return air, it is necessary to check whether there is cross-contamination.

Personnel and material channels . The location of doors, transfer windows, and openings affects area boundaries. When people or materials enter from one area to another, particles may be introduced, and boundary management must be taken into consideration.

corresponding to the sampling point . For each declared level area, the sampling points must be representative of the actual conditions in the area. Sampling points in the background area cannot be used to prove the level of local protection zones.

As mentioned in What is the Difference Between Cleanliness Grade and Filtration Efficiency? Grade evaluates the spatial particle concentration, and the representativeness of the sampling point directly affects the validity of the conclusion. This needs to be paid more attention to when labeling at multiple levels.

Test records must match claims

When accepting multi-level projects, test records must be able to correspond to each statement.

Record status separately . Which level is measured under static conditions and which level is measured under dynamic conditions should be recorded clearly. You cannot use static results for dynamic declarations.

Record the particle size separately . Different grades may use different statistical particle sizes, which should be noted in the test report. How Class 100, Class 1,000, and Class 10,000 correspond to ISO grades . The same applies to multi-grade projects. The importance of uniform particle size and caliber is explained in

Record the sampling locations separately . The location, number and sampling methods of sampling points in each area should be recorded. If only a partial workstation is verified, the report scope should be clearly written to avoid misunderstanding by purchasers or users of the performance of the entire room.

Keep complete records . The equipment operating status, personnel conditions, and door opening conditions during the test should be recorded. During subsequent audits or modifications, this information is the basis for determining whether the original class statement is still valid.

Device configuration must support partitioning

Multi-level labeling often means that equipment configurations also need to be partitioned.

Local protection . FFU or EFU can be used to provide local high-clean air supply in key workstations or inside equipment. FFU clean air supply products include standard products and customized solutions. For equipment-side applications, please refer to EFU equipment side fan filter unit。

background environment . Room background zones can be maintained by FFU arrays or centralized air supply systems. Filter selection should be based on the target level and actual pollution load. The HEPA and ULPA filter pages have parameter descriptions for different levels of products.

Partition control . The air supply volume and operation mode may be different in different areas. If the operating status needs to be adjusted at different time periods, the control system must be able to support partition and time-sharing control. The FFU group control system can configure operation strategies by region and time period.

Pressure differential management . The pressure difference relationship between different grade areas must be clear to prevent air from low-grade areas from flowing back into high-grade areas. Differential pressure monitoring and regulating devices should be included in the plan.

Aili Industrial has manufacturing capabilities in motors, fans, control systems, sheet metal, air filters and complete machine assembly. When doing a multi-level clean room project, you can put the filters, fans, structures and control conditions of different areas in the same project and check them so that the partition configurations match their respective level statements.

Scene judgment

An electronic assembly workshop has set up two ISO 5 partial protection zones in the ISO 7 background room, corresponding to two precision assembly equipment.

During project acceptance, the background area is sampled according to ISO 7, and the two protected areas are sampled according to ISO 5 respectively. The sampling points and status are in one-to-one correspondence on the drawings. The test records are filed separately, and the report scope is clearly stated as 'Applicable to local protected areas'.

During subsequent maintenance, if any local air supply equipment is shut down for maintenance, it will affect the grade status of the corresponding protection zone. Recovery verification steps need to be clearly defined in the maintenance plan. How to Update the Level Description of a 100,000-level workshop is also applicable to the maintenance and update of multi-level projects. The technical condition verification method mentioned in

Another project marked two levels, static ISO 6 and dynamic ISO 7, in the same room, but did not specify the scope of each application in the document. The customer raised questions during the review, and later added a status description and corresponding test report.

These two situations illustrate that there is no problem with multi-level labeling itself, provided that the scope and conditions are clearly written.

Key points for selection and acceptance inspection