What does the breakthrough concentration on a chemical filter report mean?

When looking through performance reports for chemical filters, the term 'breakthrough concentration' appears frequently. But what it refers to specifically may be used differently in different reports.

One usage is to refer to outlet concentration. That is, the target gas concentration measured downstream of the filter. The inlet concentration is high and the outlet concentration is low, indicating that the filter section is working; the outlet concentration begins to rise, indicating that the medium is gradually consumed.

Another usage is the penetration criterion in life testing. In the test where the target gas is continuously introduced, when the outlet concentration reaches a certain agreed value, or reaches a certain ratio of the inlet concentration, the filter material is considered to have 'penetrated'. This agreed value is the penetration criterion.

If the report only writes 'penetration concentration' without explaining which definition it is, data interpretation will be prone to deviations. For specific report interpretation, please refer to Discussion of why chemical filter performance reports list specific target gases .

Distinguish between readings and criteria

The outlet concentration is the measurement result, and the penetration criterion is the agreed condition. The two cannot be confused.

The outlet concentration is real-time data. In life testing, the outlet concentration changes with time or cumulative load. It may start low and gradually increase as the media is consumed.

The penetration criterion is the agreed end point. For example, it is agreed that if the outlet concentration reaches 5% of the inlet concentration, it is considered to be penetrated, or it is agreed that the outlet concentration reaches a certain absolute value (such as 1 ppm). This criterion determines when the test ends, and also determines which state the reported 'capacity' or 'life' corresponds to.

Lifespan and capacity cannot be directly compared when different reports use different thresholds. One report gives the life according to the 1% penetration criterion, and the other gives the life according to the 10% penetration criterion. It is meaningless to compare the two values ​​together. For specific differences, please refer to Discussion of the difference between initial efficiency and lifetime efficiency of chemical filters .

Check entrance stability

The breakthrough concentration is directly related to the inlet concentration, and the inlet conditions must be stable.

Changes in inlet concentration affect outlet and ratio calculations. If the inlet concentration fluctuates during the test, the outlet concentration will also change. The penetration criterion defined according to the entrance ratio may be triggered earlier or later.

When interpreting penetration curves, inlet concentration, air volume, and ambient records should be maintained. The breakthrough curve is the variation curve of outlet concentration with operating time or cumulative load. Only by recording the inlet conditions and operating parameters together can we determine whether the curve change comes from media consumption or inlet load changes.

Avoid looking only at final penetration time. Both reports say 'breakthrough time 500 hours', but one inlet has a high concentration and the other has a low concentration, and the actual processing loads are completely different. When comparing, look at the cumulative load, not just the time. For specific life assessment, please refer to Discussion of how long chemical filters last .

Corresponding project replacement requirements

The test penetration threshold is not necessarily equal to the allowable concentration in the field.

Sensitive equipment may need to be inspected or replaced sooner. The test ends according to the 5% penetration criterion, but the field equipment may require the outlet concentration to be lower than 1%. In this case, the filter material no longer meets the on-site requirements before reaching the test penetration criterion.

The replacement criteria should be determined according to the protection objectives. How much the outlet concentration needs to be replaced depends on the requirements of the protected object, rather than the penetration criteria in the test report. The on-site replacement threshold should be clearly defined in the project documents and the frequency of testing should be set. For specific replacement criteria, please refer to Discussion of how long chemical filters last .

Breakthrough concentration and removal efficiency are related. Removal efficiency = (inlet concentration − outlet concentration) ÷ inlet concentration. The outlet concentration increases and the removal efficiency decreases. The breakthrough concentration can be viewed as the outlet state when the removal efficiency drops to a certain level. For specific calculations, please refer to Discussion on how to calculate the removal efficiency of chemical filters .

Project judgment example

A certain project received two chemical filter reports, both of which stated 'breakthrough time is approximately 600 hours.'

The first report: the inlet concentration is 50 ppm, and the penetration criterion is that the outlet concentration reaches 5% of the inlet.
Second report: The inlet concentration is 10 ppm, and the penetration criterion is that the outlet concentration reaches 0.5 ppm (also 5% of the inlet).

The two reports have different inlet concentrations and different cumulative treatment loads. A direct comparison of 600 hours is meaningless. It is necessary to convert the cumulative load based on the actual inlet concentration and air volume of the project, and then evaluate how long the filter material can last.

This case illustrates: penetration concentration and penetration criteria should be considered together with the inlet conditions. involving When selecting a chemical filter product series , it is recommended that the project inlet concentration, air volume and outlet requirements be provided to the supplier for verification.

Key points for selection and acceptance inspection

About Aili Industrial’s penetrating data package

The interpretation of penetration concentration needs to be judged in combination with entrance conditions, penetration criteria and on-site protection objectives.

Aili Industrial has independent manufacturing capabilities in filters, motors, fans, control systems and sheet metal processing, and can provide chemical filter product series and supporting air supply equipment. For projects that need to check penetration data, the target gas, inlet concentration, air volume and outlet requirements can be combined to help confirm the applicability of the report data and the replacement criteria. When the filter is matched with MAU, FFU, EFU and other equipment, the sampling point location and maintenance method can be confirmed uniformly.

Related products:Chemical filter product series、MAU box chemical filter、FFU comes with chemical filter . Providing target gas, inlet load and outlet requirements when enquiring, can help confirm the appropriate solution. The specific selection is subject to the technical documents and test results confirmed by the project.