How to distinguish the efficiency of 0.12 micron, 0.3 micron and MPPS of ULPA?

These three words often appear in the same information or discussion, but they actually mean different things.

0.12 microns and 0.3 microns are specific particle size values. The report says '0.12 micron efficiency 99.999%', which means the efficiency measured at this specific particle size. It only describes the results for this particle size.

MPPS is a concept of evaluation method. It refers to the particle size range in which particles can relatively easily pass through the filter material under specified conditions. MPPS efficiency is the efficiency measured under the most unfavorable particle size conditions.

The three cannot be unconditionally interchangeable. An efficiency data of 0.3 microns cannot prove that the product meets the standard at 0.12 microns; an efficiency of a fixed particle size cannot replace MPPS efficiency as the basis for grade determination.

What does fixed particle size mean?

The efficiency data of a fixed particle size describes 'how the product performs at this particle size.'

Its scope of application is limited. If the project focuses on this particle size, the data can be used as a direct reference; if the project focuses on other particle sizes, this data does not explain much.

The relationship between particle size and efficiency is not monotonic. As mentioned before when talking about MPPS, the particle penetration rate has a relatively high point as the particle size changes. 0.3 microns may be more easily blocked than 0.12 microns, or vice versa, depending on the specific filter media and test conditions. You cannot judge intuitively that 'the smaller the size, the harder it is to filter.'

So when we see the efficiency data of a fixed particle size, we first ask two questions: How was this particle size selected? Is it consistent with the particle size of concern for the project?

What judgment is MPPS used for?

MPPS is not some fixed value, it is found through testing.

The test method is roughly as follows: use particles of different particle sizes to measure the penetration rate, find the interval with higher penetration rate, and determine the MPPS. The efficiency of the product is then measured at this most unfavorable particle size.

ULPA grade determination is usually based on MPPS efficiency. According to the classification of EN 1822 or ISO 29463, U15, U16, and U17 correspond to the lower limit of the overall efficiency under MPPS conditions.

The value of MPPS is related to multiple factors: filter material type, air flow speed, and detection method. The MPPS of glass fiber filter media is usually between 0.12 and 0.25 microns, and PTFE may be different. So for the same U15, the MPPS of different products may not be exactly the same.

How to avoid document confusion

If both fixed particle size efficiency and MPPS efficiency appear in the data, it is recommended to list them separately.

Indicate the test object for each data. Whether it is a filter material sample or a complete finished product determines the applicable scope of the data.

Indicate test conditions. Test air volume, aerosol type, and detection methods are all prerequisites for interpreting the data.

If the project has requirements for a specific particle size, separate testing will be agreed upon. For example, some processes are sensitive to 0.1 micron particles, and efficiency data at this particle size can be requested. But this data is a supplement to MPPS efficiency, not a replacement.

Don't convert across conditions. The efficiency data of 0.3 microns cannot be directly inferred to the performance of 0.12 microns; the efficiency data of filter materials cannot be directly used to prove the grade of the entire machine. involving For products of different grades of HEPA/ULPA air filters , the report interpretation methods are the same, and the criteria are implemented according to the corresponding standards.

Project judgment example

The customer specified '0.12 micron ULPA with an efficiency of 99.9995% or above', but the supplier's quotation only said '0.3 micron efficiency 99.999%'.

These two data cannot correspond directly. Need to confirm with the supplier: Is there any test data under 0.12 micron conditions? If not, is it possible to supplement the test?

Also confirm: Is the project really focused on the particle size of 0.12 microns, or is it a broader particle control target? If the process requirement is indeed efficiency at 0.12 microns, then this indicator must be written into the procurement document; if it is just general particle control, MPPS efficiency may be sufficient, and there is no need to specify additional particle size.

Supporting FFU fan filter unit or When the fan filter unit at the end of the EFU equipment is used, the particle size efficiency requirements of the end filter element and the verification method of the whole machine should also be clearly stated in the contract.

Selection and Acceptance Checklist

About Aili Industrial’s particle size data cooperation

The prerequisite for interpretation of particle size efficiency data is to understand its test conditions.

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. The efficiency data of the corresponding model can be provided according to the project agreement, and the test standards and conditions can be noted. filter with When the FFU fan filter unit and EFU are delivered together, the corresponding relationship between the efficiency data and the whole machine verification can be checked uniformly.

Inquiring about the particle size range and efficiency requirements of concern will help confirm the appropriate detection solution. Specific performance is subject to the testing data of the corresponding model.