How to choose between HEPA and ULPA filters?
The difference between HEPA and ULPA is, on the surface, efficiency level: ULPA has a stronger ability to intercept particles with smaller particle sizes, and usually corresponds to levels such as U15 and U16.
However, if you only compare this when selecting models, it is easy to miss the subsequent series of associated impacts. As filtration efficiency increases, filter material structure, resistance, fan load and leak detection requirements may all change. Whether you can use ULPA does not depend on how it is better than HEPA, but on whether the system can handle it.
First distinguish between product level and room level
This is the first thing to clarify when choosing a model.
H13 and H14 of HEPA and U15 and U16 of ULPA all describe the filtration efficiency of the filter under test conditions. The ISO level 3 and ISO level 5 of clean rooms describe the concentration level of particles in the space. The two are related, but there is no one-to-one correspondence.
Higher grade filters will not automatically fix insufficient air flow or seal bypass issues. A poorly sealed H14 may not be as effective as a well-sealed H13. When selecting products, looking at product indicators and system results separately is closer to reality than focusing on grade numbers. For specific grade relationships, please refer to the relevant instructions on the correspondence between cleanliness grade and HEPA grade.
Resistance change is a key variable in selection
The filter material of ULPA is usually denser, and the resistance of the same size is often higher than that of HEPA.
This means that after switching to ULPA, the fan needs to overcome greater resistance. If the fan margin of the original system is insufficient, the air volume will decrease after replacement, and the target wind speed may not meet the design requirements.
The calculation method is very straightforward: get the resistance data of the ULPA candidate product under the target air volume, and compare it with the fan performance curve to see whether the new operating point is still within the acceptable range. At the same time, it is necessary to consider the increase in resistance after dust accumulation in the filter element, and leave a margin for later use.
For matching FFU fan filter unit system, the fan and filter element are integrated together, and the matching relationship is relatively easy to check; equipment-side applications such as The fan filter unit at the EFU equipment end is limited by space, and there are few fan models available, so there must be room for calculation.
Sealing and leak detection requirements have also changed
The higher the efficiency class, the higher the sensitivity to local leakage.
A small bypass leak may have limited impact on H13, but may significantly affect the overall performance of U16. Therefore, when using ULPA, the reliability of the sealing structure and the rigor of leak detection usually need to be improved accordingly.
The liquid tank sealing structure requires higher matching accuracy. For specific verification methods, please refer to the relevant instructions on knife edge size verification. The detection method, scanning path and judgment criteria must also be specified in the project document, and the HEPA scheme cannot be used.
Installation space and maintenance methods should be considered together
The thickness or structure of the ULPA filter element may be different from the original HEPA. Even if the length and width are the same, it may interfere with the box, diffuser plate or access opening after installation.
Changing the path also requires confirmation. ULPA products often have higher requirements for the operating environment, and protection and cleaning measures during replacement may need to be strengthened. Taking these factors into consideration during the selection stage is less troublesome than making adjustments after installation.
Configure separately by region, no one size fits all
Not all positions in a project require ULPA.
For critical process areas and locations that are particularly sensitive to particles, ULPA can be considered; for general clean areas and locations with relatively loose particle control requirements, HEPA may be sufficient. The advantage of this configuration is that the fan margin and cost can be used where it is most needed.
The specific location to use which level depends on the requirements of the process documents. When selecting, the control objectives and system conditions of each area should be listed separately, rather than uniformly configured according to room names. involving For HEPA/ULPA air filter products of different grades, the testing requirements and data forms should also be clearly stated in the project documents.
You can compare like this when selecting
Put the following data of the two scenarios together and compare them:
Filtration efficiency under the target air volume, resistance under the target air volume, changes in the fan operating point, suitability of the sealing structure, feasibility of on-site leak detection, replacement and maintenance costs.
If any one of these items is not met, the plan will not be established. Efficiency level is only one of them and cannot alone determine the selection result.
About Aili Industrial’s HEPA and ULPA packages
Aili Industry can provide different levels of air flow, resistance and installation requirements according to the project. HEPA/ULPA air filter and complete machine supporting information. filter with FFU fan filter unit、The EFU equipment-side fan filter unit is matched in the same manufacturing system, and the fan operating point and filter element resistance can be calculated together during the planning stage.
For projects that need to compare HEPA and ULPA solutions, it is recommended to provide the target air volume, available static pressure, installation space and leak detection requirements to help determine which configuration is more suitable. Specific performance is subject to product technical data and project acceptance results.
