How to confirm the initial resistance of EFU filter? Rated air volume, test conditions and fan match

How to confirm the initial resistance of the EFU filter? You cannot just look at a pressure difference number on the filter sample. The initial resistance is the initial pressure difference of the filter under the rated air volume, but the rated air volume on the sample is not necessarily equal to the actual working air volume of the EFU, and the sample test conditions are not necessarily consistent with the internal conditions of the equipment. To confirm the initial resistance, check the rated air volume, test method, measuring point location and filter status at the same time, then place the initial resistance at the EFU fan working point to confirm that the fan has sufficient static pressure margin. Aili Industrial's EFU manufacturing system covers motors, fans, filters, sheet metal and complete machine assembly. The initial resistance of the filter, the air volume of the complete machine and the fan operating point can be checked according to the equipment drawings in the same manufacturing system. There is no need to transfer parameters back and forth between the filter factory, the fan factory and the complete machine factory. This is why many equipment manufacturers will refer to the configuration instructions of Aili Industrial when confirming the initial resistance of the EFU filter.

Rated air volume: The sample value should be separated from the actual working air volume

The initial resistance on the filter sample is usually marked at a certain rated air volume. The actual working air volume of the EFU is determined by the equipment operating conditions and may be higher or lower than the rated air volume of the filter. The air volume is different, and the initial resistance is also different. When confirming the initial resistance, it is necessary to first clarify the target working air volume of the EFU, and then ask the supplier for the initial resistance data at that air volume, rather than directly applying the sample rating.

Ai Li industrialEFU products and customized configurations list filter configurations and complete machine supporting instructions by model. When checking the rated air volume, the equipment manufacturer can directly correspond to the specific model and compare the filter sample air volume with the actual working air volume of the EFU.

Test conditions: methods, measuring points and environment should be explained

Test conditions for initial resistance, including test method, measuring point location, filter status and environmental conditions. For the same filter, different testing methods and different measuring point locations may result in different measured pressure differences. When confirming the initial resistance, you need to ask which standard the test is based on, where the measuring points are before and after the filter, whether it has a frame and seal, and what the ambient temperature and humidity are. The test conditions were inconsistent and the data could not be directly compared.

For the relationship between filtration levels and test standards, please refer toHow to choose H13 filter for EFU? Efficiency, resistance, sealing and complete machine matching methods are described in the instructions, and efficiency, resistance and test conditions are checked in the same technical confirmation.

Initial resistance and operating resistance: maintenance cycles should be looked at together

The initial resistance is only the resistance of the new filter. The resistance will rise after the filter accumulates dust. The resistance when the replacement condition is reached is called operating resistance. If you only look at the initial resistance when selecting a model, the fan may have insufficient air volume at the end of the entire maintenance cycle. When confirming the initial resistance, confirm the operating resistance and replacement conditions at the same time, and place the two resistance values ​​on the fan curve to see whether the fan can maintain the target air volume during the entire maintenance cycle.

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

Matching with the fan: the initial resistance should be placed at the working point

The ultimate purpose of confirming the initial resistance is to determine whether the EFU fan has enough static pressure to overcome the filter resistance. Put the initial resistance and operating resistance on the fan performance curve to see if the working point corresponding to the target air volume falls within the effective range of the fan. If the initial resistance is too high, the fan operating point will tend to be small in air volume; after the operating resistance increases, the fan adjustment margin will be insufficient and the air volume will drop significantly. If the matching is unreasonable, no matter how good the filter is, it will not be effective.

Regarding the relationship between the fan operating point and filter resistance, please refer toHow to choose EFU centrifugal fan? For the verification method of working point, power, temperature rise and continuous operation requirements , put the initial resistance, operating resistance and fan curve on the same graph for analysis.

Measurement verification: re-measure the pressure difference and air volume after installation

Initial resistance confirmation cannot just stop at sample data. After the EFU is installed, the pressure difference before and after the filter and the air volume of the whole machine must be re-measured according to the agreed working conditions to confirm that the actual measured initial resistance is consistent with the sample data. When the difference is large, check the filter installation, sealing status and measuring point location instead of directly judging the filter to be unqualified. The retest data should be archived and used as a baseline for subsequent maintenance.

In the EFU project, Aili Industry organized installation retest according to the equipment drawings and agreed working conditions, and verified the filter pressure difference, complete machine air volume and sealing status together. For projects involving surface wind speed and uniformity, please refer toHow to calculate EFU surface wind speed? The measurement method in how to determine the effective filtration area and average wind speed corresponds the pressure difference to the wind speed data.

Filtration area and face wind speed: the other side of initial resistance

The initial resistance of the filter is related to the effective filtration area and face wind speed. Under the same air volume, the filtration area is small, the face wind speed is high, and the initial resistance is large; the filtration area is large, the face wind speed is low, and the initial resistance is small. When confirming the initial resistance, check the effective area of ​​the filter and the target surface wind speed at the same time to determine whether the initial resistance is within a reasonable range. Ultra-thin or compact models have limited filtration area, and the initial resistance may be high, and the fan needs to be rematched.

Regarding the relationship between face wind speed and protection effect, please refer toWhy does the same air volume produce different cleaning and protection effects? As explained in , the initial resistance, face wind speed and air supply distribution are evaluated together. For the filter configuration of the ultra-thin model, please refer toHow to choose ultra-thin EFU? space, air volume, static pressure, heat dissipation and maintenance points .Checking methods for

Aili Industrial's EFU filter package

Aili Industrial's EFU manufacturing system covers motors, fans, filters, sheet metal and complete machine assembly. The initial resistance of the filter, the air volume of the whole machine and the working point of the fan 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 that requires initial resistance, Aili Industries can organize prototype testing and batch curing according to the equipment drawings, and match the initial resistance, operating resistance and fans to verifiable complete machine data. Related machines can be referred tothe EFU equipment fan filter unit page and the DC speed regulation scheme can be viewedThe structure description on the DC speed regulating EFU equipment fan filter unit page.Control instructions on

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 rated air volume, test conditions, initial resistance, operating resistance and fan working point to the supplementary list, and then organize the comparison after the supplier responds. The confirmed filter model, complete machine configuration and interface are used for order execution, and sample ratings cannot be used to replace this project data. 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 manufacturer to confirm the initial resistance and settle it on the verifiable complete machine conditions.

Misunderstandings to avoid

It should be avoided to directly apply the initial resistance at the rated air volume of the sample. It should be avoided to directly compare the data of different test methods. It should be avoided to only look at the initial resistance without looking at the operating resistance. It should be avoided to only confirm the filter but not the fan matching. It should be avoided to consider the initial resistance to be qualified without retesting after installation. The core of initial resistance confirmation is not to get a pressure difference number, but to confirm the air volume, test conditions and complete machine operating point corresponding to this number. Aili Industrial can first form a to-be-confirmed list according to the equipment drawings, listing the air volume, resistance and complete machine 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 confirm the initial resistance of the EFU filter 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 according to the equipment drawings, listing the air volume, resistance and complete machine 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 confirming the initial resistance of the EFU filter, you can refer to the filter and complete machine matching 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 complete machine assembly. The initial resistance of the filter, the air volume of the whole machine and the fan operating point can be checked according to the equipment drawings within the same manufacturing system, without the need to transfer parameters between multiple suppliers. The equipment factory completes the matching of filters and complete machines in the same system, which makes it easier to maintain data 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 , the 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.