What should I do if the cleanliness of the process equipment drops after it is started?

The decrease in cleanliness after process equipment is started is a common problem at the production site. The test passed when the equipment was stationary, but an increase in particles occurred once it was running. This situation is often related to equipment dust production, hot air flow, exhaust changes or mechanical obstruction, rather than a sudden drop in filter efficiency.

When troubleshooting, you should first record the relationship between anomalies and equipment actions, observe them in stages, and then decide on the direction of treatment. The following will start from the stages of observation, dust generation sources, hot air flow, exhaust changes, and mechanical shielding.

Observe the production cycle in stages

The operation of process equipment often consists of several stages: start-up, movement, heating, venting and shutdown. Different stages have different effects on particles.

When recording, observations should be made in stages:

• Startup moment: whether there is a particle peak;

• Movement stage: whether it is synchronized with the action of the mechanism;

• Heating stage: whether temperature changes are accompanied by particle changes;

• Exhaust stage: Does the start and stop of the exhaust affect the air flow?

• After shutdown: Whether the particles gradually recover.

Observing in stages can help narrow down the problem. If particles only rise during a certain phase, the problem may be related to actions or conditions during that phase. To determine the operating status of the equipment during acceptance, please refer to Which equipment should be in operation during acceptance?。

Mechanical actions produce dust

Moving parts of equipment, guide rails, belts and transmission mechanisms may generate particles during operation. Wear, insufficient lubrication or poor sealing can increase dust production.

During inspection you should pay attention to:

• Whether there is obvious wear on moving parts;

• Is the lubrication condition normal?

• Whether dust is being released from the facility;

• Whether the particle rise is synchronized with the action.

If particles are synchronized with mechanism actions, priority should be given to source isolation or local exhaust rather than just increasing the filtration level. Higher filtration efficiency has limited effect on downstream dust production, please refer to Does higher filtration efficiency necessarily lead to improved site ratings?。

Thermal plumes change the direction of airflow

When the equipment heats up, it will generate a thermal plume. The hot air rises and may change direction when it meets the supply air flow, forming a local backflow or vortex. The impact of thermal plumes is more obvious on precision equipment and high heat load stations.

During inspection, you should confirm:

• The location and temperature of the heating area;

• Whether the thermal plume conflicts with the air supply direction;

• Whether the particle rise is synchronized with the heating phase;

• Whether it is necessary to adjust the air supply direction or increase the exhaust air.

For backflow problems caused by thermal plumes, please refer to Why is it easy for contamination to accumulate in the return flow area? , to understand the formation mechanism of local circulation.

Process exhaust changes affect airflow balance

Process equipment is often equipped with an exhaust system. When the exhaust is started or switched, the pressure and air flow direction inside and around the equipment will be changed.

During inspection you should pay attention to:

• Whether the exhaust air volume is balanced with the supplemental air volume;

• Whether the protective airflow is drawn away when the exhaust is started;

• Whether there is negative pressure inside the equipment;

• Check whether background air is sucked in due to negative pressure when opening the door or maintenance port.

An imbalance between exhaust and make-up air will cause airflow paths to change. For the calculation method of air volume balance, please refer to How to convert the clean area area into air supply demand?。

Mechanical shading changes protection boundaries

The mechanical structure, fixtures, manipulators and pipelines of the equipment may block the air supply and change the local protection boundary. When the device is running, changes in the position of the moving parts will also change the occlusion status.

Observe during inspection:

• Whether moving parts block the air supply surface;

• Whether the fixture and workpiece are in the airflow shadow area;

• Whether the protection boundary changes when the manipulator extends;

• Whether key workstations are always covered effectively.

For airflow planning in closed equipment cavities, please refer to How to plan clean air supply for closed equipment cavities? , understand the relationship between internal structure and airflow path.

Choose the direction of correction based on reasons

The rectification directions for different reasons are different:

• Mechanical dust generation : isolate dust-generating components, increase local exhaust, and optimize lubrication and maintenance;

• Thermal plume : adjust the air supply direction, increase local exhaust air, and optimize the position of heating components;

• Changes in exhaust air : balance exhaust air and supplementary air, adjust exhaust position and air volume;

• Mechanical shielding : adjust equipment layout, change air supply direction, and increase local protection.

After rectification, retest under the same operating conditions to confirm particle recovery. Insufficient maintenance channels will increase subsequent expenditures. This is reflected in what later expenses will be increased due to insufficient maintenance channels . There is a more detailed analysis of

Relationship to system carrying capacity

A drop in cleanliness after process equipment is started may also reflect insufficient system carrying capacity. If equipment operation increases pollution loads or exhaust requirements, the original system may not be able to maintain protection.

When judging, you should check:

• Is the air supply volume sufficient?

• Whether the return air channel is clear;

• Whether the filter resistance increases;

• Whether the system recovery time is extended.

When the system's carrying capacity is insufficient, it may be necessary to adjust the device configuration or operating settings. For issues regarding system recovery capabilities, please refer to What particle problems can airflow short circuits cause?。

Equipment selection and terminal matching

The rectification involves equipment and filtering configuration, please refer to FFU clean air supply products and EFU equipment side fan filter unit . Filter installation, sealing and leak detection requirements can be learned HEPA and ULPA filters . If you are still unclear about the difference between space rating and filter efficiency, you can read What is the difference between cleanliness level and filtration efficiency?。

Project judgment example

When a piece of equipment is running, the particles at the station are high, but normal when stationary. The investigation found that the manipulator extended out and blocked part of the air supply surface, and the product was in a weak protection zone. Adjustment method: Adjust the air supply direction and increase local protection so that key locations are always within effective coverage. The particles dropped after adjustment.

In another project, the wind speed at the workstation dropped after the exhaust of the equipment was started. The investigation found that the exhaust air volume was greater than the supplemental air volume, and the protective airflow was taken away. Adjustment method: Adjust the balance of exhaust air and supplementary air, and increase the supplementary air path. The wind speed recovers after adjustment.

These two situations indicate that the cleanliness of the process equipment has dropped after it is started. This needs to be observed in stages and investigated item by item. It cannot be directly attributed to insufficient filtration level.

Key points for selection and acceptance inspection

Aili industrial equipment supporting support

The cleanliness of process equipment decreases after it is started, which involves multiple factors such as dust generation from the mechanism, hot air flow, changes in exhaust air, and mechanical obstruction. Aili Industrial has collaborative capabilities in fans, motors, filters, control systems and complete machine assembly links. It can cooperate to check the air supply direction, air flow path, exhaust balance and protection boundaries during equipment operation inspections, helping to determine whether the source of the abnormality is the equipment itself, air flow organization or system load, rather than just adjusting based on particle readings. Specific models can be viewed FFU clean air supply products , the supporting equipment can be viewed EFU equipment end fan filter unit , please refer to the filter package. HEPA and ULPA filters。