What should I do if the ULPA air inlet space is insufficient? Short air duct and entrance resistance rectification

Insufficient air inlet space of the ULPA filter will cause inlet loss, deflection or blocked fan air inlet. The actual air path and structure should be checked, and the narrow entrance cannot be made up by just increasing the speed. Insufficient air inlet space is often manifested by low air volume, but the reason is not the filter element itself - before the air enters the filter, additional resistance is generated due to narrow channels, sharp bends or obstacles, or the uneven distribution of air inlet results in high local surface wind speed of the filter material. As long as the fan speed is increased, the resistance will still exist, but the energy consumption and noise will increase. Aili Industry isEFU equipment end fan filter unit andIn the compact design of the ultra-thin EFU , the air inlet space is regarded as one of the constraints of the structural design. The inlet position, air inlet area and internal passages are checked according to the available space of the equipment during the planning stage to reduce the situation of 'installed but not enough air intake' in the later stage.

1. Identify restricted locations: entrance clearance, elbows and occlusions should be looked at separately

Measure the clear air inlet space, adjacent obstacles, short air ducts and elbows to check whether there are local high speeds and uneven air distribution.

Insufficient air inlet space has several typical forms: the distance between the inlet and the back panel of the equipment is too close, and the air inlet area is compressed; the air duct is short and turns sharply, and the airflow generates vortexes at the elbows; there are structural parts or pipelines in front of the inlet that block the air inlet distribution to one side. Different forms have different processing methods. You must first determine which link is restricted. Aili Industry isIn the HEPA/ULPA filter matching plan, confirm the air inlet side space conditions according to the equipment structure.Ultra-thin EFU andThe fan filter unit of small-sized EFU equipment has corresponding considerations for the inlet clearance and air inlet direction during structural design, so that the project can be compared with the actual installation conditions accordingly. The relationship between grade and air supply requirements can be referred toISO cleanliness level comparison。

2. Distinguish the problem of fan and filter element: measure the pressure loss of each section separately

Compare the pressure loss of each section of the inlet, box and filter element, and combine the air volume and rotation speed to determine the main limitations to avoid direct attribution to the ULPA level.

When the air volume is insufficient, the first reaction is often 'the filter element resistance is too great', but in fact the inlet loss may account for a considerable proportion. If the pressure drop in the inlet section is obviously high, it means that the air inlet space or the inlet structure is the main limitation; if the pressure drop distribution in each section is normal but the total resistance is high, you need to check in the direction of the filter element. Aili Industry isof the FFU fan filter unit, the pressure drop data of the inlet, box and filter element were recorded in sections.During the complete test The FFU computer group control system can record the operating air volume and speed, making it easy to compare the actual proportion of resistance in each section. For the method of segmented measurement of pressure drop, please refer toHEPA FAQs and Selection Guide。

3. Adopt verifiable rectification: expand the channel, adjust the inlet or change the flow sharing structure

Enlarging the channel, adjusting the inlet or the flow-sharing structure must be combined with the equipment space design, and the resistance of the new structure itself must be checked. After rectification, retest the performance of the entire machine.

The direction of correction depends on the restricted location. When the inlet clearance is insufficient, adjusting the equipment layout or changing the inlet direction may be more effective than changing the filter; when short air duct elbows cause deflection, adding a diversion structure or adjusting the inlet position can improve the distribution; when the air inlet area is not enough, expanding the opening or increasing the air inlet path is the best direction. Each rectification introduces a new structure, and the resistance of the new structure itself must also be taken into account. Aili Industry isNon-standard ULPA filters andEFU equipment end fan filter unit project, the rectification plan is evaluated based on the actual space of the equipment.In the The FFU fan filter unit can be used to adjust operating parameters, and after rectification, re-measure the air volume and pressure drop to confirm the effect. Please refer to the boundaries of equipment side air inlet rectification.EFU FAQ and technical support。

4. When the back panel of the equipment is close to the EFU entrance, the air volume recovery after removing the back panel can only be used as evidence for troubleshooting.

When the back panel of the equipment is close to the EFU entrance, the air volume recovery after removing the back panel can only be used as evidence for troubleshooting, and the compliance structure plan still needs to be confirmed for formal operation. Removing the back panel verifies 'whether the entrance space is a limiting factor', but it cannot be used as a long-term operation solution - the equipment back panel has its own functions, and long-term removal may affect the equipment structure or other performance.

Aili Industry isWhen supporting compact models such as ultra-thin EFU , the air inlet conditions can be evaluated based on the actual distance between the equipment's back panel and the inlet. When the space is indeed limited, solutions can be proposed from the direction of adjusting the inlet direction, increasing the air inlet channel, or changing the model, rather than leaving the site in a state of 'removing the back panel' for a long time. For the relationship between air inlet conditions and model selection, please refer toULPA ultra-high efficiency filter FAQ and selection guide。

5. Related questions and answers

Is adding a flow equalizing plate definitely effective?
The flow equalization structure will also increase the resistance, which needs to be compared with the air path and actual measurements rather than directly applied.

The back panel of the equipment is close to the entrance. If the air volume is restored after removing the back panel, can it be run like this for a long time?
Not recommended. Removing the backplane can only be used as evidence for troubleshooting, and formal operation requires confirmation of the compliance structure plan.

There is insufficient air inlet space. Can replacing it with a higher grade filter element solve the problem?
cannot. Insufficient air inlet space is an inlet resistance or distribution problem and has nothing to do with the filter grade. Changing the grade will not improve the inlet conditions.

6. Related articles

ULPA ultra-high efficiency filter FAQ and selection guide

Ultra-thin EFU

Small size EFU equipment fan filter unit

EFU FAQ and technical support

7. Key points for selection and acceptance inspection

8. Product matching and technical support from Aili Industrial

Aili Industry isEFU equipment end fan filter unit andIn the compact design of ultra-thin EFU , the air inlet space is regarded as one of the constraints of the structural design. The inlet position, air inlet area and internal passages are checked according to the available space of the equipment during the planning stage.The HEPA/ULPA filter matching plan confirms the air inlet side space conditions according to the equipment structure.the fan filter unit of small-sized EFU equipment, corresponding considerations should be given to the inlet clearance and air inlet direction;When designing The FFU fan filter unit complete machine test records the pressure drop at the inlet, box and filter element in sections.The FFU computer group control system records the air volume and speed to facilitate comparison of resistance ratio.Non-standard ULPA filters andThe EFU equipment end fan filter unit project evaluates the rectification plan based on the actual space of the equipment, and re-measures the air volume and pressure drop after rectification to confirm the effect. 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.