What items should be checked during daily inspection of chemical filters?

Inspection of chemical filters is not the same as that of particulate filters.

The particle filter depends on the pressure difference. If the pressure difference rises to a certain value, replace it. The pressure differential of a chemical filter may not change much over its lifetime, but the gas handling capacity may have quietly declined. Just looking at the pressure gauge may not necessarily reveal the problem.

Routine inspections should cover several aspects: operating status, seal appearance, target gas outlet trend, and usage records. The following is expanded according to the actual inspection sequence.

View system and installation

During each inspection, first check the operating status of the filter and system.

Air volume and fan status. Record the current air volume or fan gear. If the air volume decreases, it may be due to changes in system resistance, fan failure, or blockage of the filter section. Changes in air volume will affect the gas treatment effect and cannot be ignored.

The filter segment is in fixed state. Check whether the filter element is displaced, loose or vibrating. Vibration during equipment operation may cause the filter element to slowly deviate from the installation position, causing sealing failure.

Frames and access doors. Check whether the frame sealing gasket is detached, whether the access door is closed tightly, and whether there are any abnormalities in the interface. Bypass air leakage will allow untreated air to bypass the filter material, and the outlet concentration may increase. For specific inspection methods, please refer to Discussion on how to check frame bypass after chemical filter installation .

When abnormal vibration, deformation or moisture is found, trace the cause first and do not continue to use it directly. For specific compression issues, please refer to Discussion of the use problems that may occur if the chemical filter has insufficient pressing force .

Record load changes

Inspection is not just about looking at the equipment, but also recording changes in operating conditions.

Hours of operation. How long has the filtering segment been running cumulatively? Continuous operation and intermittent operation have different consumption rates.

Material and process changes. Have you changed cleaning agents, adhesives, and solvents recently? Have the process parameters been adjusted? These changes may change the composition and concentration of gaseous pollutants and affect filter material consumption. For specific differences, please refer to Discussion on why chemical filters should be selected according to target gases .

Contamination incident records. Has there been a leak, unusual release, or high-level exposure? Such events may accelerate the consumption of filter media, and follow-up inspections should focus on this. For specific investigation methods, please refer to whether to do air sampling before choosing a chemical filter . Discuss

Changes in production conditions may indicate the need for maintenance earlier than appearance. Recording the load information and analyzing it together with the outlet concentration data can more accurately judge the condition of the filter material.

Track corresponding gases

The core task of the chemical filter is to process the target gas, and inspections should pay attention to the outlet concentration trend.

Arrange inspections according to protection objectives. Is it equipment anti-corrosion, process protection or deodorization? The detection methods and frequencies corresponding to different targets are different. For specific detection methods, please refer to Discussion of sampling points for chemical filter performance verification .

Outlet concentration trends are more important than single readings. The efficiency of new filter material is usually high when it is first put in. As the running time increases, the outlet concentration may gradually increase. Regularly testing the outlet and recording the changing trends can help determine the timing of replacement. For specific efficiency calculations, please refer to Discussion on how to calculate the removal efficiency of chemical filters .

Don’t judge just by smell. Some gases have no obvious odor, and some gases have an impact on the process at low concentrations. Only outlet concentration testing can provide objective data. For specific differences, please refer to Discussion of whether chemical filters can remove ammonia from the air .

The pressure difference is used to understand the air flow resistance, and the gas capacity needs to be supported by corresponding indicators. Record the two separately and do not replace each other. For specific differences, please refer to Discussion on whether the chemical filter can be replaced based on the pressure difference .

Inspection records and archiving

Inspection results should be recorded.

Record content: inspection date, operating air volume or gear, pressure difference, outlet concentration, appearance inspection results, problems found and treatment methods.

Corresponding location. The installation position corresponding to each filter section or module should be clearly marked in the record. During subsequent replacement or troubleshooting, the corresponding product can be found directly.

Trend analysis. Putting multiple inspection data together can better reflect the changes in filter material status than single data. If the outlet concentration gradually increases and the air volume gradually decreases, it may be that the filter material is nearing the end of its life. For specific life assessment, please refer to Discussion of how long chemical filters last .

Replacement and maintenance history. Every time you replace filter media, adjust compression components, or deal with sealing problems, record the date, reason, and result. This information can help optimize the next maintenance plan.

Project judgment example

During the inspection of the chemical filter of a certain project, it was found that the air volume dropped but the gas readings were normal.

The preliminary judgment is that the system resistance has increased. The inspection found that the pre-filtration section was heavily dusted, resulting in a decrease in the air volume passing through the chemical filtration section. After cleaning the pre-filter, the air volume is restored and the outlet concentration of the chemical filter section returns to the normal range.

The inspection record of another project only said 'normal' and there was no outlet concentration data. After running for a period of time, corrosion of the equipment was suddenly discovered. I looked back at the records and could not tell when the outlet concentration started to rise.

These two cases illustrate that the inspection record must cover air volume, pressure difference and outlet concentration, and cannot just write 'normal'. involving When selecting chemical filter product series , it is recommended to provide the inspection items, detection methods and recording formats to the supplier for verification.

Key points for selection and acceptance inspection

About Aili Industrial’s inspection and maintenance packages

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 require the formulation of inspection plans, we can assist in checking inspection items and record formats based on target gases, system conditions, testing requirements, and maintenance methods. When the filter is matched with MAU, FFU, EFU and other equipment, the location and maintenance method of the sampling port can be confirmed uniformly.

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