What are the effects of using compressed air to purge clean areas?

Compressed air is widely used in industrial sites and is often used for drying, dust removal and cleaning equipment. But in clean areas, compressed air blowing is a double-edged sword: if used well, it can clean the local area; if used improperly, it will resuspend particles, disrupt the protective air flow, and even bring oil, water or particles in the pipeline to the vicinity of the product.

To determine whether compressed air purging is available, you need to consider the quality of the air source, the direction of the nozzle, the operating area and the exhaust path, rather than just looking at whether the air source is equipped with a filter.

The quality of air source and user end must be controlled separately

Compressed air goes from the air compressor to the end of use, passing through pipelines, filters and drying devices. Just because the outlet quality of the air compressor is qualified does not mean that the air at the end of use is also qualified. Rust, condensation, oil mist and particles in the pipeline may be brought out during purging.

When checking, you should confirm the following:

• Particle filtration level;

• moisture content and dew point;

• oil content;

• Pipe cleanliness status;

• Use point filter status.

Only checking the air compressor configuration does not guarantee that the air at the end of use is suitable for the clean area. For specific filtering configuration, please refer to HEPA vs ULPA filters , learn about filtration levels and installation methods.

The purge action resuspends surface particles

When compressed air is purged, the airflow hits the surface and resuspends the deposited particles into the air. These particles may spread to the surrounding area and be carried into the product location by the protective air flow.

The harder and wider the purge, the more particles are suspended. In clean areas, blown particles may enter adjacent workstations, return air vents or product protection zones.

The direction of the nozzle determines the pollution diffusion path

The direction of the nozzle directly affects the direction of particle diffusion. If the nozzle is directed towards the product, workstation or air return vent, particles may be carried to sensitive locations.

When judging, please pay attention to:

• Whether the nozzle is facing the product or operating area;

• Whether the air flow blows particles to adjacent workstations;

• Whether particles are blown into the return air vent or exhaust vent;

• Whether the purge area is downstream of the protective air flow.

Proper purge direction should keep particles away from sensitive areas and into locations where they can be eliminated. For lateral interference treatment in open workstations, please refer to How to establish a local clean area in an open workstation? , understand the management ideas of airflow boundaries.

Purging disrupts local protective airflow

The air flow generated by compressed air purging may conflict with the clean supply air flow and disturb the local protection boundary. When purging in a local protected area or workbench, the protective air flow may be blown away, forming an instantaneous weak protected area.

For the influence of purging action, please refer to How will operating the arm interfere with the air supply to the workbench? , learn how to troubleshoot local airflow interference.

Necessary purges should be carried out in controlled locations

If the process requires compressed air purging, it should be done under controlled conditions:

• Choose a location that does not interfere with sensitive workstations;

• Use air that meets the quality requirements of the user end;

• Control nozzle direction and pressure;

• Evaluate isolation or trapping conditions;

• After purging, confirm that the protected area is restored.

Arranging purging outside the clean area or in an isolated area can reduce the impact on the protected area. If it must be done in a clean area, the exclusion path and recovery conditions should be confirmed.

Post-Purge Recovery and Verification

After purging, particles may still be suspended in the air. You should wait for the reading to return to the specified range before proceeding with sensitive operations.

Verification content includes:

• Particle recovery trends in the purge area;

• Whether adjacent workstations are affected;

• Whether the protective air flow is restored to stability;

• Whether additional cleaning steps are required.

To judge the recovery trend, please refer to Is it normal for particle readings to increase after floor cleaning? , learn how to evaluate particle changes after cleaning operations.

Relationship to other pollution control measures

Compressed air blowing is not a substitute for normal cleaning and maintenance procedures. Filters, airflow organization, and personnel and material management still need to function properly.

If particle problems occur frequently in a clean area, the sources of contamination and airflow paths should be examined rather than temporarily dealt with by purging. For source investigation when particles exceed the standard, please refer to How to distinguish external and internal contamination when particles exceed the standard?。

Project judgment example

In a certain project, the fixture was purged next to the open workstation, and the particles increased significantly. Investigation revealed that the purge blew particles to adjacent workstations. Adjustment method: Move the purge to an isolated area, use compressed air that meets the requirements, and control the direction of the nozzle. After adjustment, the particles of adjacent stations are restored.

Another project was purging the equipment cavity, and the quality of the air source at the user end was not confirmed. After purging, oil mist and particles were found locally. Adjustment method: Add end-use filtration and drying devices, confirm the air quality and then re-evaluate. After adjustment, the air at the use end meets the requirements.

These two situations illustrate that the impact of compressed air purging is not only on the air source, but also on the purging direction, area selection and elimination path.

Key points for selection and acceptance inspection

Aili industrial equipment supporting support

The impact of compressed air purging involves air source quality, purging direction, area selection and system recovery. Aili Industrial has collaborative capabilities in fans, motors, filters, control systems and complete machine assembly links. It can cooperate in checking the air quality at the end of use, local airflow status and protection area recovery during operation management, helping to judge whether the purging operation is suitable for the current workstation conditions, and whether it is necessary to adjust the purging method or add isolation measures. Specific models can be viewed FFU clean air supply products , supporting equipment can be viewed EFU equipment end fan filter unit , please refer to the filter package. HEPA and ULPA filters。