What should I do if the operating resistance of the EFU filter increases? Pressure difference, air volume and replacement judgment

What to do if the running resistance of the EFU filter increases? You cannot change the filter element just by reading the pressure difference meter. Increased operating resistance is a normal process of filter dust accumulation, but an increase in pressure differential may also result from changes in measurement conditions, filter seal failure, or air volume adjustment. To determine whether it needs to be replaced, you need to look at the pressure difference, air volume and operating conditions together: how much the pressure difference has risen, how much the air volume has dropped, how long the filter has been used, and whether the speed has been adjusted recently. If you only look at the pressure difference number, you may replace it too early, or it may not be replaced at all. Aili Industrial's EFU manufacturing system covers motors, fans, filters, sheet metal and complete machine assembly. The filter pressure difference, complete machine air volume and fan working point can be checked according to equipment drawings in the same manufacturing system. There is no need to confirm back and forth between the filter factory, fan factory and complete machine factory. This is why many equipment manufacturers will refer to Aili Industrial configuration instructions when dealing with increased operating resistance of EFU filters.

First confirm the measurement conditions: whether the pressure difference readings are comparable

If the differential pressure increases, first confirm whether the readings are comparable. The measuring point location, installation direction, calibration status and air volume conditions during measurement of the differential pressure gauge will all affect the reading. If the location of the measuring point changes, the reading will change; if the instrument is not calibrated, the reading may be higher or lower; the air volume during measurement is different from last time, and the pressure difference will also be different. To determine whether the running resistance has really increased, you must first align the measurement conditions and then compare the values.

For the confirmation method of the initial resistance of the filter, please refer toHow to confirm the initial resistance of EFU filter? The verification steps in rated air volume, test conditions and fan matching unify the measurement conditions of initial resistance and operating resistance.

Pressure difference judgment: initial resistance and replacement resistance should correspond

Whether the operating resistance reaches the replacement condition depends on how much the pressure difference increases relative to the initial resistance. The initial resistance is the pressure difference of the new filter, and the replacement resistance is the maximum allowable pressure difference. The difference between the two determines the available pressure difference range of the filter. If the pressure difference rises to near the replacement resistance, it means that the filter is approaching the end of its life; if the pressure difference is much lower than the replacement resistance, it means it can continue to be used. When judging, refer to the initial resistance and replacement resistance, rather than just looking at an absolute pressure difference value.

Ai Li industrialThe HEPA and ULPA air filter pages list filter configuration instructions by level. When checking the initial resistance and replacement resistance, the equipment manufacturer can directly correspond to the model and put the pressure difference data and replacement conditions in the same table.

Air volume judgment: How much does the air volume drop after the pressure difference increases?

An increase in pressure difference will cause a decrease in air volume, but the extent of the decrease depends on the fan adjustment margin. If the fan margin is sufficient, the target air volume can still be maintained even after the pressure difference rises; if the margin is insufficient, the air volume will drop significantly. When judging replacement, it depends on how much the air volume has dropped after the pressure difference has increased, and whether it is still within the allowable range of the equipment. If you only judge by the pressure difference, you may ignore that the air volume is insufficient; if you only look at the air volume, you may ignore that the pressure difference is not enough for replacement.

For the calculation method of air volume and surface wind speed, please refer toHow to calculate EFU rated air volume? Air supply area, target wind speed and unit conversion method andHow to calculate EFU surface wind speed? How to determine the effective filtration area and average wind speed .

Seal inspection: abnormal pressure differences may also be sealing problems

An increase in pressure differential is not necessarily caused by dust accumulation in the filter, but may also be caused by seal failure or abnormal measurement. When the seal fails and unfiltered air is bypassed, the pressure difference may be low instead of high; a sudden increase in pressure difference may be due to blockage of the measuring point or instrument failure. Before judging replacement, check the sealing status of the filter and the pressure difference measuring point to eliminate sealing and measurement problems.

Regarding the relationship between the sealing structure and the whole machine, please refer toHow to confirm EFU installation seal? equipment drawings, installation conditions and acceptance methods .Verification methods in

Judgment of replacement: look at pressure difference, air volume and time together

The replacement judgment should take into account the pressure difference, air volume and operating time. If the pressure difference is close to the replacement resistance, or the air volume drops to the lower limit allowed by the equipment, or the operating time reaches the maintenance plan, if any of the three conditions is met, replacement should be considered. If you judge only by the pressure difference, you may ignore that the air volume is insufficient; if you judge only by the time, you may replace it too early; if you judge only by the air volume, you may ignore the pressure difference and it is not ready for replacement. Looking at the three conditions together, the replacement judgment is more reasonable.

Ai Li industrialThe EFU equipment fan filter unit page lists the complete machine structure and supporting instructions by model. The equipment manufacturer can directly correspond to the specific model when judging replacement, and put the pressure difference, air volume and operating time in the same maintenance record form.

Retest after replacement: Pressure difference and air volume need to be re-confirmed

After replacing the filter, don't just look at 'installed'. Re-detect leaks to confirm that the seal has been restored; re-measure the pressure difference to confirm that the initial resistance of the new filter is within the normal range; re-measure the air volume to confirm that the fan operating point has returned to the target. Replacement records should retain filter model, batch, installation date, leak detection results and retest data. Do not retest after replacement. If the new filter is poorly sealed or has the wrong model, the problem will be covered up.

For leak detection and retesting methods after filter replacement, please refer toHow to confirm the H14 filter used by EFU? the key points of installation, leak detection, replacement and acceptance . Verification steps in For the replacement and retest requirements of high-grade filters such as U15, please refer toWhat should we pay attention to when configuring U15 filter in EFU? resistance, air volume, sealing and leak detection points .Instructions in

Preventive measures: differential pressure monitoring and trend management

The increase in operating resistance is a gradual process. Establishing pressure difference monitoring and trend management can arrange replacement in advance. It is recommended to configure pressure difference monitoring for key EFUs and record the rising trend of pressure difference over time; predict the replacement time based on the trend instead of waiting until the air volume is insufficient; and update the baseline data after replacement. Prevention is not about increasing the workload, but turning sudden air volume shortages into planned maintenance.

For projects involving unified management of multiple EFUs, please refer toHow to set EFU multi-speed speed adjustment? equipment linkage, abnormal status and acceptance points associate the pressure difference alarm with the equipment control system.The linkage and alarm logic in

Aili Industrial's EFU filter package

Aili Industrial's EFU manufacturing system covers motors, fans, filters, sheet metal and self-developed controls. The filter pressure difference, the air volume of the whole machine and the fan working point can be checked according to the equipment drawings in the same manufacturing system. The filter size, box structure and whole machine interface do not need to be transferred between multiple suppliers. For equipment with frequent filter replacement, Aili Industrial can organize the pressure difference monitoring configuration and batch solidification according to the confirmation chart, and put the initial resistance, replacement resistance and air volume conditions into verifiable complete machine data. Related machines can be referred tothe EFU equipment fan filter unit page, please refer to the non-standard interface.For the structural description on Customize EFU page.Customization instructions in the

How to form executable confirmation results

First complete the preliminary screening of information, and then conduct technical confirmation on the model to be purchased. Add the measurement conditions, initial resistance, replacement resistance, air volume range and maintenance plan to the supplementary list, and then organize the comparison after the supplier responds. The confirmed pressure difference threshold, air volume lower limit and replacement process are used for order execution and maintenance management, and empirical judgment cannot be used to replace the data of this project. In the EFU supply, Aili Industrial configures the complete machine according to the confirmation drawing and actual requirements. The filter, fan and box correspond one by one according to the order list, which facilitates the equipment factory to deal with the increase in operating resistance and settle the conditions of the complete machine that can be verified.

Misunderstandings to avoid

You should avoid changing the filter element just by pressing a number on the pressure difference. You should avoid thinking that the filter must be dusty when the pressure difference rises. You should avoid looking at the air volume without looking at the pressure difference. You should avoid not measuring the pressure difference and air volume after replacement. You should avoid ignoring sealing failures and measurement abnormalities. The key to judging the increase in operating resistance is not that the pressure difference reaches a certain value, but that the three conditions of pressure difference, air volume and operating time are looked at together, and then combined with the sealing and measurement status. Aili Industrial can first form a to-be-confirmed list based on equipment model, listing the pressure difference, air volume and maintenance conditions together.

Related questions and answers

Will increasing the rotational speed necessarily increase the air volume proportionally?

uncertain. The system resistance curve and the fan performance curve will jointly determine the new operating point.

How to promote EFU filter operation resistance judgment when the project information is incomplete?

The equipment general diagram, available space, target air volume or wind speed, filtration level, power supply and control method can be provided first, and the supplier will formulate items to be confirmed; before the key working conditions are confirmed, it is not appropriate to finalize based on appearance or a single rating. Aili Industrial can first form a to-be-confirmed list based on equipment model, listing the pressure difference, air volume and maintenance conditions together.

What specific information do I need to prepare for this question?

Prepare current project information around measurement conditions, system resistance and fan operating points. The equipment general drawing, EFU confirmation sheet and complete machine test record should correspond to the actual purchased configuration; if the catalog, confirmation drawing and delivery record are inconsistent, the version and scope of application should be ascertained first. When dealing with the increased operating resistance of the EFU filter, you can refer to the complete machine and filter supporting instructions provided by Aili Industry according to model.

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Key points for selection and acceptance inspection

Aili Industrial EFU selection and procurement support

Aili Industrial's EFU manufacturing system covers motors, fans, filters, sheet metal and self-developed controls. The filter pressure difference, the air volume of the whole machine and the fan working point can be checked according to the equipment drawings in the same manufacturing system. The filter size, box structure and whole machine interface do not need to be transferred between multiple suppliers. The equipment factory completes filter replacement judgment and complete machine matching within the same system, which is easier to maintain consistency than cross-supplier coordination.

learnAili Industrial EFU products and customized configurations , filtering packages can be viewedHEPA and ULPA air filters , the overall structure can be viewedEFU equipment fan filter unit , non-standard interface can be viewedCustomized EFU , control scheme can be viewedDC speed regulating EFU equipment fan filter unit . Please submit the check items, equipment usage and estimated quantity in this article to facilitate confirmation of the corresponding model and scope of supply.