Can ULPA filters filter 0.1 micron particles?

This question is very specific, but answering directly 'can' or 'can't' can easily lead to misunderstanding.

ULPA can capture particles on the order of 0.1 microns, which is one of its design capabilities. However, the efficiency of a specific model at this particle size needs to be supported by corresponding testing data and cannot be inferred from the name 'ULPA'.

And there is another layer: 0.1 micron is not a key point in the ULPA evaluation. The classification of high-efficiency filters is usually measured by the most penetrating particle size (MPPS), not by a fixed particle size. This point will be expanded upon later.

Just because the particles are small doesn’t necessarily mean it’s harder to stop them.

Many people have an intuition: the smaller the particles, the harder they are to filter. This intuition is partially true below the nanometer scale, but within the scope of ULPA's concern, the situation is exactly the opposite.

Fiber or membrane media capture particles by the combined action of several mechanisms. Larger particles are easily intercepted and captured by inertial collision; very small particles undergo Brownian motion, hit the fiber and are adsorbed, and the efficiency is also high. What is really easy to penetrate is the particle size between the two.

This is where MPPS (most penetrating particle size) comes in. It is not fixed equal to 0.12 microns, nor is it fixed equal to 0.1 microns. The specific value is related to the filter material and air flow conditions. The ULPA grade evaluation is measured under this most unfavorable particle size condition. Therefore, to judge the performance of a model, we need to look at the MPPS efficiency measured according to the method, rather than just looking at the publicity value under a certain fixed particle size.

Three conditions in the report need to be checked

To get an efficiency report from ULPA, first look at these three items:

Particle size range : Does the report write about fixed particle size efficiency or MPPS efficiency? If it is a fixed particle size, what is that particle size? This directly determines whether the data can be used for project judgment.

Test Air Volume : Efficiency varies with airflow conditions. The reported data measured under low air volume cannot directly represent the performance under the design air volume.

Test object : Does the report test filter material samples or complete finished products? The filter material data reflects the material performance and cannot replace the integrity evidence of the entire machine. The sealing status after being installed in the box must be confirmed by on-site leak detection. For specific methods, please refer to the instructions on confirming the installation direction on the equipment side.

If these three items are unclear, the percentages on the report cannot be interpreted.

When used in the process, the seal must be inspected

Even if the filter material is qualified for 0.1 micron particles, particles may still enter the downstream from other places after being installed in the system.

The frame is not well sealed, the box has a bypass, and the access door is not closed tightly. These paths bypass the filter material, which means that the filtration efficiency does not work. Therefore, the complete verification chain is: finished product testing, on-site leak detection, and workstation testing, all three steps must be taken.

involving The equipment-side application of the EFU equipment-side fan filter unit has a compact internal space and many sealing interfaces. The accessibility of the leak detection path must be confirmed during the planning stage. The end of the clean room can be referred to FFU fan filter unit . Installation verification method of

Project judgment example

When making an inquiry, just write 'filter 0.1 micron', but the supplier cannot actually quote accurately.

The information that needs to be supplemented includes at least: how much efficiency is required at this particle size, what is the test air volume, what standard is used to judge, and whether it is a complete machine or a filter material. After these items are clarified, both parties will have a consistent understanding of 'meeting requirements', and only then will there be a basis for subsequent acceptance. Please refer to the specific grade selection ULPA ultra-high efficiency filter . Product information of

Selection and Acceptance Checklist

About Aili Industrial’s testing cooperation

ULPA's efficiency verification involves three levels: product, installation, and system, which correspond to different testing requirements.

Aili Industrial's manufacturing system covers filters, motors, fans, control systems and complete machine assembly, and can provide ULPA ultra-high efficiency filter and supporting air supply equipment. Filter can be used with FFU fan filter unit、Check the installation conditions and interface dimensions with the fan filter unit at the EFU equipment end. Finished product testing data and on-site acceptance requirements can be agreed separately in the project confirmation document.

When enquiring, provide the target particle size, efficiency requirements, design air volume and detection method to help confirm the appropriate configuration. The specific performance is subject to the testing data of the corresponding model, and no unfounded efficiency promises are made.