Can level 300,000 be directly converted into ISO level?

Direct answer: It is not appropriate to directly equate it to an integer ISO grade.

Level 300,000 is a title in the traditional cleanliness level. At a caliber comparing particle concentrations of no less than 0.5μm, it falls roughly between ISO 8 and ISO 9, rather than being exactly equal to one of them. If it is written directly as ISO 8 or ISO 9, the original requirements will either be tightened or relaxed. Both approaches may leave disputes for subsequent acceptance.

Therefore, when dealing with the 300,000-level annotation, the focus is not to find a number to replace, but to clearly trace the technical conditions in the original document, and then restate it in conjunction with current standards and actual needs.

Let’s first trace back to the 300,000-level definition in the old document.

The meaning of level 300,000 may not be exactly the same in different documents.

The three hundred thousand level in the design description usually describes the design goal and may correspond to static conditions. The 300,000 level in the process file may correspond to the requirements under production status and is closer to dynamic conditions. The 300,000 level in the acceptance record records the actual status and method during the test that year.

Get an old document marked with 300,000 levels, and check these items first: of the original standard version 、statistical particle size 、and volume units 、Test status of . If these pieces of information are missing, there will be no complete basis for conversion.

How do Level 100, Level 1,000, and Level 10,000 correspond to ISO levels? The difference between traditional titles and ISO expression calibers is mentioned. The traceability logic for level 300,000 is the same, except that it does not fall on a certain integer level, and the original definition needs to be checked.

Concentration conversion is not equal to grade mapping

Some people will try to convert 300,000 levels into concentration per cubic meter, and then refer to the ISO table to find the nearest level. This idea has certain reference value, but it cannot be directly used as a hierarchical conclusion.

The reason is that ISO levels are not continuously interpolated by concentration. The standard gives the limit value of the integer level, and there is a blank interval between the two integer levels. The converted concentration of 300,000 levels may fall between ISO 8 and ISO 9, or it may fall somewhere else due to different original standard particle sizes, units or states.

In addition, ISO standards have applicable ranges for combinations of grades and particle sizes. Under certain particle size conditions, some grades are not applicable. You cannot fill in the blank space of the table with a certain value by yourself, nor can you extend it with unfounded formulas.

It has been emphasized in What is the Difference Between Cleanliness Level and Filtration Efficiency that the grade evaluates the spatial particle concentration, not the filter efficiency. These two levels must also be distinguished when converting.

How to write contracts and technical documents

When updating the 300,000 level, it is recommended to list the complete technical conditions in the technical document instead of just replacing a level name.

Possible expressions include:

Write the concentration limit according to the actual control target . If the project has clear requirements for particle concentration, you can directly state the allowable concentration not less than a certain particle size, and indicate the measurement status and area boundaries.

Use integer ISO grades plus supplementary requirements . If ISO 8 is chosen as the benchmark, requirements not covered in the original document need to be supplemented, such as other particle size conditions, sampling methods or special area restrictions.

The traditional title is retained for clarification . You can indicate in the document 'Originally marked 300,000 level, now implemented according to the following technical conditions' to maintain a traceable relationship between old documents and current requirements.

The update method mentioned in How to Update the Level Description of a 100,000-level workshop is also applicable to the 300,000-level workshop: name conversion and technical condition verification are handled separately to avoid changing just the text.

Equipment configuration needs to be rechecked

After the level description is updated, the equipment configuration needs to be rechecked according to the new technical conditions.

Filtration efficiency . Confirm the actual particle control requirements for the target area and select the corresponding grade of filter. The HEPA and ULPA filter pages have parameter descriptions for different levels of products.

Air volume static pressure . Check the air supply volume based on area volume, ventilation needs and pollution load. Whether the old fan still has enough margin needs to be calculated based on the actual resistance curve.

Airflow organization . Confirm the relationship between supply air coverage, return air path and pressure difference. The location of the air supply vents in the old scheme may not be suitable for the new layout.

control method . If zone control or duty mode is required, the control system must be able to support it. The FFU group control system can configure operation strategies by region and time period.

Aili Industrial has manufacturing capabilities in motors, fans, control systems, sheet metal, air filters and complete machine assembly. When updating grade files and renovating old factory buildings, you can put filters, fans, structures and control conditions in the same project to check, so that the equipment configuration and updated technical conditions match. Related products can be viewed FFU clean air supply products , please refer to the local purification at the equipment end EFU equipment side fan filter unit。

Scene judgment

An old packaging area is only marked with a level of 300,000, and it is planned to change the entire area to ISO 8 during expansion. After the evaluation, it was found that the concentration limit corresponding to the original 300,000 level was looser than ISO 8. Directly changing to ISO 8 would increase the requirements and require increasing the air supply volume or adjusting the filtration configuration. The project team later reconfirmed the control objectives based on actual product exposure levels and original limits, without directly applying integer levels.

Another project directly wrote the 300,000 level as ISO 9, and passed the inspection according to ISO 9 during acceptance, but the customer proposed that the original document requirements may be more stringent during the review. After looking back, I discovered that there was a supplementary requirement regarding a specific particle size in the old document, which had been omitted.

These two situations illustrate that the conversion of 300,000 level cannot just be a name replacement.

Key points for selection and acceptance inspection