How to test the uniformity of ULPA air outlet? Measurement point layout and abnormality investigation

The ULPA filter air outlet uniformity test should be conducted at specified operating conditions and measurement points, and the average value and distribution of each point should be recorded. Only measuring the center or only looking at the average wind speed may miss edge low speeds and local drifts. The most common problem with uniformity testing is 'measure the center, calculate the average, and write it as qualified.' The central wind speed is often the highest on the entire air supply surface, and the average value cannot reflect whether there is a low-speed zone at the edge. Uniformity needs to answer 'how much is the difference between the points on the air supply surface'. The layout of measuring points and data analysis must focus on this question. In the structural design stage of the whole machine, Aili Industry takes the uniformity of air outlet as the design index: the space of the static pressure box, the position of the inlet and the flow equalization structure are determined in the structural plan.FFU fan filter unit andThe fan filter unit at the EFU equipment end has testing requirements for the air distribution before leaving the factory, and the uniformity is basically guaranteed in the structure.

1. Define the measurement conditions: the plane, distance, grid and stabilization time must be written clearly.

Clarify the distance from the filter surface, measuring point grid, instrument applicability and stabilization time, avoid interference from human operations on readings, and record the structural status of protective nets and other structures.

The distance between the measurement plane and the filter surface is different, and the measured distribution shape is also different: when it is close to the filter surface, it is affected by the local wrinkle structure, and when the distance is far away, the jet has started to mix. The density of the measuring point grid determines whether local anomalies can be found. If the grid is too sparse, the low-speed area may just be skipped. Aili Industry isThe HEPA/ULPA filter supporting solution provides corresponding structural instructions according to the measurement plane and grid spacing adopted by the project.The FFU computer group control system records the operating status to facilitate maintaining stable working conditions during testing. The relationship between grade and air supply requirements can be referred toISO cleanliness level comparison。

2. Analyze distribution rather than single points: focus on edges, directly below the fan and near the entrance

Check the differences at the edge, directly under the fan, near the entrance and in the shelter, and determine the cause based on the static pressure box and internal structure.

The uniformity risk is different at different locations on the air supply surface. Low-speed zones are prone to form at the edges, and local high-speed zones are prone to occur directly below the fan. The speed near the entrance of the side air inlet box is high and the far end is low. These distribution characteristics are directly related to the internal structure of the box. Aili Industry isIn the box design of the fan filter unit at the EFU equipment end , the flow equalization structure is arranged according to the inlet position and static pressure space.The factory test of the FFU fan filter unit records the air distribution in a multi-point arrangement, and the test data can be mapped to specific structural positions. The relationship between surface wind speed distribution and resistance can be referred toHEPA FAQs and Selection Guide。

3. Maintain comparability after adjustment: After changing the structure or speed, use the same set of measuring points to retest.

After modifying the speed, current sharing structure or inlet, repeat the measurement using the same plane and measuring points to avoid changing the measuring points and making the results appear to be improved.

Judgment of uniformity improvement requires comparable data. If 9 points are placed on plane A for the first time and 5 points are placed on plane B after correction, the distribution characteristics of the two sets of data cannot be directly compared. Aili Industry isAfter the non-standard ULPA filter project was rectified, the measurement was repeated according to the original measurement plane and grid.Tank seal ULPA filter andThe structural adjustment of the partition-less ULPA ultra-high-efficiency filter is also verified according to the original test conditions to ensure that the data before and after the rectification are comparable. For the relationship between uniformity verification and structural adjustment, please refer toULPA ultra-high efficiency filter FAQ and selection guide。

4. When the speed near the entrance of the side air inlet box is high and the speed at the far end is low, check the flow average and space

When the speed near the inlet of the side air inlet box is high and the far end is low, the flow equalization and space should be checked instead of just reducing the entire fan speed. Reducing the rotational speed will reduce the overall wind speed, but the problem of uneven distribution will still exist - it will still be higher near the entrance, and it may become lower at the far end.

Aili Industry isWhen supporting the EFU equipment end fan filter unit , the static pressure space and flow equalization scheme are evaluated based on the side air inlet structure. When space allows, the distribution is improved through the internal structure. When space is limited, the applicable scope is explained based on the actual achievable uniformity level.Compact models such as ultra-thin EFU balance structural size and air distribution in a limited space. For the boundaries of uniformity adjustment on the device side, please refer toEFU FAQ and technical support。

5. Related questions and answers

Is it considered uniform if the average wind speed reaches the standard?
No, uniformity needs to be evaluated according to project rules, and the average cannot describe local differences.

The fewer measuring points, the easier it is, right?
Not recommended. If the grid is too sparse, the low-speed region may be skipped, and the representativeness of the uniformity conclusion will decrease.

After rectification, can I change a set of measuring points and test again?
Not recommended. The same plane and measuring points as the original test should be used so that the data will be comparable.

6. Related articles

ULPA ultra-high efficiency filter FAQ and selection guide

Ultra-thin EFU

No partition ULPA ultra high efficiency filter

HEPA FAQs and Selection Guide

7. Key points for selection and acceptance inspection

8. Product matching and technical support from Aili Industrial

In the structural design stage of the whole machine, Aili Industry takes the uniformity of air outlet as the design index. The space of the static pressure box, the position of the inlet and the flow equalization structure are determined in the structural plan.FFU fan filter unit andThe fan filter unit at the EFU equipment end has testing requirements for air outlet distribution before leaving the factory.The HEPA/ULPA filter matching program provides structural instructions according to the project measurement plane and grid spacing.The fan filter unit at the EFU equipment end is arranged with a flow equalization structure according to the inlet position and static pressure space.The complete machine test of the FFU fan filter unit is recorded and distributed according to the multi-point arrangement and corresponds to the structural position.After rectification, the non-standard ULPA filter was retested according to the original measurement plane and grid.Tank seal ULPA filter andThe structure adjustment of the partition-less ULPA ultra-high-efficiency filter is verified according to the original test conditions;Ultra-thin EFU balances structural size and air distribution in a limited space.The FFU computer group control system records the operating status to facilitate maintaining stable working conditions during testing. Provide process objectives, installation drawings, operating conditions and acceptance requirements for further communicationULPA ultra-high efficiency filters . Standard specifications, non-standard interfaces, samples and batch matching of The specific parameters and test range are based on the confirmed model and technical documents.