How to calculate EFU surface wind speed? How to determine the effective filtration area and average wind speed

How to calculate the EFU surface wind speed? You cannot just use an air volume number divided by the length and width of the box. To calculate the face wind speed, you must first determine the effective filter area, and then divide the target air volume by the effective area to get the average face wind speed. The effective area is not the external area of ​​the box, but the actual air outlet area of ​​the filter, excluding the portion occupied by the frame and pressure frame. After the average wind speed is calculated, it is also necessary to look at the distribution and dispersion of the measuring points. If the average reaches the standard, it does not mean that every location reaches the standard. Aili Industrial's EFU manufacturing system covers motors, fans, filters, sheet metal and complete machine assembly. The effective filtration area, target wind speed and complete machine working point can be checked in the same technical confirmation according to the equipment drawings. This is why many equipment manufacturers will refer to the Aili Industrial configuration instructions when calculating the EFU surface wind speed.

Effective filter area: first deduct the border and then calculate

The first step in calculating face wind speed is to determine the effective filter area. The EFU box has a frame, flange and pressure frame. These parts do not participate in air supply. If you directly use the box shape area to calculate, the surface wind speed obtained will be low. It seems that the wind speed is enough, but the actual air supply surface may be too high or unevenly distributed. The correct approach is to calculate based on the actual size of the air outlet surface of the filter, deduct the width of the frame, and calculate based on the total area when there are multiple filters.

Ai Li industrialEFU products and customized configurations list the filter size and complete machine supporting instructions by model. The equipment manufacturer can directly correspond to the specific model when calculating the effective area, avoiding the use of external dimensions to estimate.

Average wind speed: air volume divided by effective area

After the effective filtration area is determined, divide the target air volume by the effective area to obtain the average surface wind speed. When calculating, pay attention to the uniformity of units. Whether the air volume is expressed in cubic meters per hour or cubic meters per minute, the area is expressed in square meters or square feet, and the wind speed is expressed in meters per second or feet per minute, all must be unified first and then calculated. The units are not unified, and the calculated surface wind speed may differ by an order of magnitude.

For complete conversion methods of air volume, area and wind speed, please refer toHow to calculate EFU rated air volume? the air supply area, target wind speed and unit conversion method are based on the calculation of surface wind speed under the same caliber.The calculation steps in

Measuring point layout: In addition to the mean, it depends on the distribution

The average surface wind speed is only a total indicator, and the actual protection effect also depends on the wind speed distribution. There may be high-speed areas and low-speed areas on the air supply surface. If the low-speed area happens to fall in the protected area, particles may have a chance to enter. When calculating surface wind speed, it is necessary to explain the arrangement of measuring points, the number of measuring points, and the location of measuring points at the same time. Use multi-point measurements to calculate the average value and relative standard deviation to determine whether the wind speed distribution is uniform.

Regarding the relationship between wind speed distribution and protection effect, please refer toWhy does the same air volume produce different cleaning and protection effects? In the instructions, average wind speed and wind speed uniformity are evaluated together instead of just looking at one number.

Measurement conditions: with filter element and external static pressure must be written clearly

Face velocity is not a fixed value and varies with filter resistance and system conditions. When measuring, it is necessary to indicate whether there is a filter, what the static pressure outside the machine is, what the fan speed or control gear is, and where the measurement plane is on the air outlet surface. The face wind speed measured without a filter cannot represent the actual wind speed after installation.

In the EFU project, Aili Industrial checked the measurement conditions according to the equipment drawings and agreed working conditions, and recorded the filter status, external static pressure and fan gear position to avoid direct comparison of the face wind speed measured under different conditions. For measurement methods, please refer toHow to evaluate EFU wind speed uniformity? measuring points, average values, deviations and acceptance methods .Description of

Match the whole machine: the surface wind speed should return to the air volume and static pressure

After the face wind speed is calculated, it is necessary to return to the overall air volume and static pressure to confirm. The target surface wind speed corresponds to the target air volume, and the target air volume corresponds to the fan operating point. If only the face wind speed is given but not the air volume static pressure, the fan selection cannot be determined; if only the air volume is given but not the face wind speed, the air supply coverage cannot be determined. Both should be placed in the same table and checked together with the filter resistance and fan operating point.

In the EFU project, Aili Industrial checked the air volume, surface wind speed and fan working point according to the equipment drawings and agreed working conditions, and confirmed the target surface wind speed based on the conditions of the whole machine, instead of selecting based on just one wind speed number. Equipment manufacturers check fans, filters and boxes within the same manufacturing system, making it easier to keep data consistent than transferring parameters across suppliers.

Aili Industrial's EFU manufacturing system

Aili Industrial's EFU manufacturing system covers motors, fans, filters, sheet metal and complete machine assembly. The effective filtration area, surface air velocity and fan operating point can be checked by model within the same manufacturing system, and filter size, box structure and complete machine interfaces do not need to be transferred between multiple suppliers. For equipment that requires uniformity of wind speed, Aili Industrial can organize prototype testing and batch curing according to the equipment drawings, and put the surface wind speed, measuring point layout and complete machine data into verifiable complete machine data. Related machines can be referred tothe EFU equipment fan filter unit page.Structural description 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. Include the effective filtration area, target surface wind speed, measurement point layout, measurement working conditions and complete machine working points in the supplementary list, and then organize the comparison after the supplier responds. The confirmed face air speed, air volume and complete machine configuration are used for order execution, and sample parameters 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 manufacturer to calculate the face wind speed and settle it on the verifiable complete machine conditions.

Misunderstandings to avoid

It should be avoided to use the box shape area instead of the effective filter area, to avoid direct comparison of data from different units, to avoid measuring only the center point to represent the entire air outlet surface, to avoid measuring the surface wind speed without a filter element, and to avoid looking at the average wind speed without looking at the distribution. The average wind speed reaching the standard does not mean that the protection effect reaches the standard. When the low-speed zone falls in the protection zone, particles may still enter. Aili Industrial can first form a to-be-confirmed list according to the equipment drawings, listing the area, wind speed 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 advance EFU surface wind speed calculation 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 area, wind speed 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 calculating the EFU surface wind speed, 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 complete machine assembly. The effective filtration area, surface air velocity and fan operating point can be checked by model within the same manufacturing system, and filter size, box structure and complete machine interfaces do not need to be transferred between multiple suppliers. The equipment factory completes the matching of surface wind speed and complete machine in the same system, which is 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 . Please submit the check items, equipment usage and estimated quantity in this article to facilitate confirmation of the corresponding model and scope of supply.