Can chemical filters handle both particulate matter and gases?

This problem often arises in project communication. Some people hope that a layer of filters will solve all problems, trapping particles and removing gases. However, from the perspective of filtration mechanism, the main task of a chemical filter is to deal with gaseous pollutants. Its ability to intercept particles is limited and cannot automatically be equivalent to a qualified particle filter.

If you need to control particles and gases at the same time, there are usually two ideas: hierarchical combination, or using composite products that have proven performance in both categories. Both ideas have their own applicable conditions and cannot be confused. For specific division of labor logic, please refer to Discussion of the difference between chemical filters and HEPA filters .

Two pollution forms are evaluated separately

Particles and gases are two different types of pollutants, and their evaluation standards are also different.

Particle filtration focuses on particle size range, filtration efficiency, installation sealing and on-site leak detection. The HEPA or ULPA rating describes the ability to intercept particles of a specific size.

Gas filtration focuses on target gas species, removal efficiency, adsorption capacity and breakthrough time. Chemical filter performance data must correspond to specific gas and service conditions.

Even if a certain chemical medium can trap some dust, it cannot be claimed to have reached the HEPA level. The particle interception mechanism of the medium is completely different from that of the high-efficiency filter, and the detection methods and judgment standards are also different. In turn, HEPA has basically no ability to deal with gas molecules. Specific products can be referred to the chemical filter product range . Description of

Graded combinations are easier to check

If the project has both particle and gas control needs, a common approach is to set up filtration sections in stages.

The pre-particle filter first blocks dust and fibers to reduce dust coverage of chemical media. Primary-efficiency or medium-efficiency filters can undertake this layer of tasks. For specific configuration, please refer to Discussion on the division of labor between chemical filters and primary filters .

The chemical filtration section treats target gases. The media type and dosage are determined based on gas composition, concentration and air volume.

The terminal high-efficiency filtration is responsible for final particle control. If the project has clear requirements for particle cleanliness, the HEPA or ULPA layer cannot be omitted.

This order is not fixed. The specific arrangement should be confirmed based on the dust load, risk of medium powder loss, temperature and humidity conditions and system resistance. For example, some chemical media may produce a small amount of dust during operation. If the chemical section is placed behind the end high efficiency, this part of the dust may directly enter the clean side, and it is necessary to evaluate whether to add a protection section.

The advantage of hierarchical combination is that the responsibilities of each layer are clear, which facilitates separate acceptance and maintenance. Different detection methods are used on the particle side and the gas side, and the records are filed separately. When a problem occurs, the problem can be quickly located on which layer. involving MAU box-type chemical filters , the sequence of filter sections is usually determined during the design phase. For fresh air systems with

Compound products also need to look at evidence

There are also some composite structure filtration products on the market, trying to achieve both particle and gas treatment in one layer.

The integrated structure can save space, but the performance needs to be verified separately. Product data should provide particle filtration data and gas treatment data respectively, and the test conditions should correspond to actual working conditions.

Replacing one layer may affect the sealing of another layer. In a composite structure, if only one layer of media is replaced, it is necessary to confirm whether the other layer is still intact and whether the seal has been restored. Just because the overall appearance has not changed does not mean that the default function remains the same.

A single percentage is not enough to explain both functions. If a product only gives a general efficiency number without specifying whether it is particle efficiency or gas efficiency, this data cannot be used for selection judgment. For specific report interpretation, please refer to Discussion of why chemical filter performance reports list specific target gases .

System matching and maintenance

Regardless of whether graded combinations or composite products are used, system-level conditions must be checked.

The resistance superposition must be calculated clearly. Increasing the filter section will increase the total resistance. When selecting a fan, it is necessary to add up the initial resistance and final resistance of filters at all levels to check whether the working point is acceptable. Supporting For FFU systems equipped with chemical filters , the unit capacity must also be checked.

Maintenance cycles are out of sync. The replacement of the particle filter is based on the pressure difference and leak detection results; the replacement of the chemical filter is based on the consumption of gas processing capacity, and there may be no obvious pressure difference change. The maintenance rhythms of the two are different, and the ledgers must be recorded separately.

There should be enough margin for the fan. If the original fan capacity is insufficient, the air volume may decrease after adding a filter section, affecting the terminal air supply. The accounting method can be referred to Discussion of how much the added resistance of the chemical filter will increase the fan's electricity consumption .

There are two lines for acceptance. The particle side performs leak detection and efficiency confirmation according to the corresponding level; the gas side performs concentration detection according to the target component. Only doing one type of testing makes it impossible to evaluate whether another type of function meets the standards.

Project judgment example

A certain piece of equipment needs to provide clean air while controlling solvent volatiles.

The preliminary plan selected a composite filtration product, thinking that it could solve two problems at the same time. After operation, it was found that the particle indicators were normal, but there was still an odor inside the equipment, and some sensitive components were abnormal.

Investigation and confirmation: The composite product has data support for particle control, but has no corresponding treatment effect on the solvent components that the project is concerned about. The gas problem remains.

Adjustment plan: retain the particle filtration section and add a chemical filtration section for the solvent. After rechecking the resistance, interfaces and maintenance methods of the two-stage filter, the system returned to normal.

This case illustrates: Composite products also depend on whether the gas data corresponds to the project goals. Just because the word 'chemistry' is in the product name doesn't mean it can handle all gases. involving When selecting a chemical filter product series , it is recommended to confirm two types of performance respectively.

Key points for selection and acceptance inspection

About Aili Industrial’s combination configuration packages

The core of the combination of particle filtration and gas phase filtration is to separately confirm the two types of requirements and then check them uniformly at the system level.

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 particle filtration products. For projects that require simultaneous control of particles and gases, the dust load, gas composition, air volume and installation space can be combined to assist in checking the filter section sequence, resistance and interfaces. When the filter is matched with MAU, FFU, EFU and other equipment, the resistance, interface and maintenance methods can be confirmed uniformly.

Related products:Chemical filter product series、MAU box chemical filter、FFU comes with chemical filter . A separate list of particle control targets and gas targets is provided during the inquiry to help confirm the appropriate combination solution. The specific configuration is subject to the technical documents and test results confirmed by the project.