The composition and source of the odor are unclear. How to choose a chemical filter?

There was a strange smell at the scene, but it was unclear what the gas was and where it came from. This kind of project is the most troublesome in the selection stage.

Some people will directly ask the supplier: 'Is there a deodorizing filter element?' But 'deodorizing' is a general term. Different odors correspond to different chemical substances, some coming from organic matter, some coming from sulfides, and some coming from ammonia. While ordinary activated carbon may be effective in treating organic odors, it has limited effectiveness in treating ammonia. When the ingredients are not clear, you just buy a general-purpose filter element. The effect is often not satisfactory after installation, and it is more troublesome to go back and check it later.

The correct sequence is: first investigate the source, then do a representative test, and then select the medium based on the test results. This process may take some time, but it is less troublesome than changing the filter element repeatedly. For specific selection logic, please refer to Discussion on why chemical filters should be selected according to target gases .

First collect the information you can get

Just because the ingredients are unclear doesn't mean there are no clues at all.

Raw material list. Solvents, cleaning agents, adhesives, lubricants, paints, etc. used on site may release odors. The safety data sheet can provide ingredient information, but please note: not all the ingredients listed in the safety data sheet will volatilize into the air. The actual release amount is also related to the use method, temperature, and degree of openness.

Occurrence period. Is the odor always present, or does it only appear during a certain process or period of time? Intermittent odors are often related to specific operations or equipment operating conditions. Recording the time of occurrence can help narrow down the source.

personnel activities. Personnel entry and exit, operating actions, and cleaning operations may introduce or generate odors. Some odors may come from outside, entering through door areas or fresh air.

neighborhood. If the factory is close to other workshops, exhaust outlets or external pollution sources, the odor may come from external input. Wind direction and time period records can help judge.

Collate this information into a preliminary list of clues. Even if the specific composition cannot be determined, it can provide direction for subsequent sampling. involving When selecting a chemical filter product line , suppliers need this background information to determine possible contamination categories.

Identify contamination in stages

Once you have initial clues, staged testing can be arranged.

Step 1: Compare different locations. Take samples separately at the fresh air inlet, return air outlet, key workstations, and areas with obvious odor. Comparing the concentration and composition differences at these locations can determine whether the contamination comes from the outside or inside, and what the transmission path is.

Step 2: Cover representative periods. If the odor is intermittent, sampling should cover the period when the odor occurs. The data measured during the pollution-free period cannot represent the actual load. Record the production status, ventilation conditions and door area status at the time of sampling.

Step 3: Detect the main ingredients. Based on preliminary clues and on-site conditions, possible target components are selected for detection. For example, if solvent volatilization is suspected, TVOC or specific organic compounds can be detected; if detergent is suspected, ammonia or amines can be detected; if external input is suspected, acid gas or sulfide can be detected.

The test should cover the period when odor occurs, and avoid using the results when there is no contamination for selection. Being below the detection limit does not mean there is no contamination and needs to be interpreted in conjunction with the protection objectives. For specific sampling methods, please refer to whether to do air sampling before choosing a chemical filter . Discuss

The connection between primary selection and verification

After the test results come out, you can initially judge the pollution type and select the corresponding media direction.

If the source is not yet complete, the primary assumptions and detection scope can be clarified first. For example, if you initially judge that the smell is mainly organic, you can first configure activated carbon or special organic media according to the organic gas, while leaving room for subsequent adjustments.

Trial is an important step in verifying model selection. Before formal purchase, you can use a small test device or temporary filter section for trial use to compare the inlet and outlet concentration and sensory changes. The working conditions should be recorded during the trial to ensure that the results are comparable. For specific trial methods, please refer to Discussion of how to set clear success conditions for chemical filter trials .

Do not promise that all unidentified gases can be treated. When the ingredients are uncertain, the plan should state the scope of application and items to be confirmed to avoid over-commitment. involving For the MAU box-type chemical filter fresh air system, it is recommended to set up sampling points in the fresh air section to facilitate follow-up tracking.

Project judgment example

A certain workshop reported a peculiar smell, but the source was unclear.

Preliminary investigation found that the odor only appeared when the equipment was heated, and was more obvious near the equipment operating area. Checking the materials list, some kind of adhesive was used in the heating process, and the safety data sheet showed it contained organic solvents.

Based on these clues, arrange sampling at the fresh air outlet, near the equipment and at the workshop return air to cover the heating period. The test results showed that the TVOC concentration near the equipment was significantly higher than other locations, and the main components were consistent with the solvent in the adhesive.

Treatment direction: First increase local exhaust at the equipment end to reduce the diffusion of solvent volatiles. At the same time, a chemical filtration section for the solvent is configured on the air supply path of the equipment. After the trial, it is confirmed that the outlet concentration and odor are significantly improved, and then the formal plan is determined.

This case illustrates that even if the composition is unclear, the target gas can be gradually identified through source investigation and phased detection. involving For equipment-side applications of FFU supporting chemical filters , it is recommended that the equipment structure and air flow path be included in the scope of investigation.

Key points for selection and acceptance inspection

About Aili Industrial’s odor investigation and selection support

For projects with unclear odor components, the core is to connect source investigation, testing and selection, rather than skipping the investigation and selecting the filter element directly.

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 identify the source of odor, on-site materials, operating conditions and airflow paths can be combined to help sort out the direction of investigation. When the filter is matched with MAU, FFU, EFU and other equipment, the sampling point location and filter section configuration can be confirmed uniformly.

Related products:Chemical filter product series、MAU box chemical filter、FFU comes with chemical filter . Providing on-site information, time of occurrence and preliminary investigation results when inquiring can help confirm appropriate testing and selection solutions. The specific selection is subject to the technical documents and test results confirmed by the project.