Do ISO 5 clean rooms have to use H14?

We often encounter this question: If we want to reach level 100, do we have to take H14?

There is a common confusion behind this question - room cleanliness level and filter level . there is a one-to-one relationship between In fact, these are two different standard systems and answer different questions.

ISO 5 describes the particle concentration of the air in the space, and H14 describes the performance of the filter under test conditions. The two are related, but cannot be directly converted. ISO 5 does not stipulate which grade of filter must be used. There are many cases of using H13 with good airflow organization in the project, and there are also cases of using H14 without good sealing and air volume distribution.

What do the two sets of standards govern?

The cleanliness level of ISO 14644 evaluates the number of particles in a unit volume of air. Reaching ISO 5 means that under specified test conditions, there are no more than 3520 particles ≥0.5μm per cubic meter. This is a description of the state of space.

H13 and H14 come from the filter efficiency classification standard, which evaluates the filtration efficiency of the filter for particles of a specific particle size. The test has prescribed air volume, dust generation method and detection means. This is a description of product performance.

One is the acceptance index of the room, and the other is the factory index of the product. When problems arise in projects, product indicators are often used to explain the room results - the filter element is reported to be qualified, but the room is not; or conversely, if the room is up to standard, it is assumed that the filter element must be fine. Neither of these inferences holds true.

What determines whether ISO 5 can be achieved is not just the filter element.

Even if equipped with H14, the room may not be up to standard. Common types of reasons:

The air supply volume is not enough. ISO 5 generally requires higher air changes and unidirectional flow coverage. The grade of the filter element is sufficient, but the air volume at the end is insufficient, and the efficiency of particle dilution and removal is insufficient.

The airflow organization is unreasonable. Insufficient coverage of the air supply surface, obstruction of the return air path, local eddy currents or short circuits will cause the particle concentration to be high in certain locations. In this case, increasing the filter element grade will provide limited improvement.

The seal is not done properly. Terminal bypass air leakage allows unfiltered air to flow directly into the clean area. No matter how high-grade the filter element is, the bypass will bypass it. Such problems need to be located through on-site leak detection. For specific troubleshooting ideas, please refer to the interface verification method of the liquid tank sealing structure.

The source of pollution itself is strong. If the particle load caused by process equipment, personnel operations, and material entry and exit exceeds the dilution capacity of the system, it cannot be solved by simply upgrading the filter element level.

Is H13 enough?

H13 can be used in many ISO 5 projects, provided the system design is in place.

The key lies in whether the entire air supply link can control particles: the air volume at the end is insufficient, the airflow coverage is incomplete, the sealing is done well, and how big the pollution load is during operation. If these conditions are met, it is feasible for H13 to achieve ISO 5 with reasonable system design. On the contrary, when H14 was installed, there were problems with sealing and air volume, and the result was still not up to standard.

Therefore, instead of worrying about H13 or H14 when selecting a model, it is better to clarify these issues first: what are the particle control requirements of the target area, how much air supply volume is required, how to organize the air flow, how to seal the end interface, and what state the acceptance should be based on. These are determined. The filter level is a derived result, not a prerequisite.

Acceptance must separate two things

It is recommended to write two types of requirements separately in the project document: the grade and testing requirements of the filter product, and the cleanliness acceptance conditions of the room.

In this way, when a problem occurs, it can be located - whether the product fails to meet the agreed indicators, or the system operating status does not meet the design requirements. Written together, the boundaries of responsibilities are unclear and the investigation has no direction.

For local areas such as semiconductor equipment, the situation is different from that of the entire clean room. The air supply unit at the equipment end needs to be calculated separately according to the equipment structure, and the configuration idea of ​​the factory clean room cannot be directly applied.

About Aili Industrial’s clean solution package

Ai Li industrial production HEPA/ULPA air filter and matching FFU fan filter unit、EFU equipment-side fan filter unit and high-efficiency air supply outlet. Filters and air supply equipment are matched in the same system. Grade selection, air volume matching and interface sealing can be confirmed together at the planning stage, instead of determining the filter element grade first and then finding system matching.

For ISO 5 projects, it is recommended to provide the target area, test status, air supply volume requirements and terminal interface together to facilitate the judgment of the more appropriate combination of filter level and system configuration. Specific performance is subject to product technical data and project acceptance results.