What should be checked if particles increase after the air conditioner is turned on?

The task of the air conditioning system is to regulate temperature and humidity, and the task of the cleaning system is to control particles. Both operate in the same space but with different goals. The increase in particles after the air conditioner is turned on indicates that the air conditioning system may have brought particles into the clean area or interfered with the local protective air flow.

The fact that the air conditioner temperature reaches the standard does not mean that the particle control is qualified. When investigating, you should start from the air supply path, filtration status, dust release and air flow interference.

First confirm the correlation between particle changes and the start and stop of the air conditioner.

The first step in the investigation is to confirm that the increase in particles is indeed related to the turning on of the air conditioner. Recording method:

• Particle baseline with air conditioning off;

• Particle change curve after the air conditioner is turned on;

• Comparison under different air conditioning operating modes;

• Where and when changes occur.

If the increase in particles only occurs when the air conditioner is turned on and is synchronized with the start and stop of the air conditioner, it is more likely that it is related to the air conditioner. If the particle changes are not related to the start and stop of the air conditioner, other sources should be investigated.

Air conditioning air supply path and filter status

The air supply path of the air conditioning system may introduce particles:

• Dust accumulates inside the air conditioning box and is carried out by the airflow after starting;

• The filter section is not tightly sealed and unfiltered air is bypassed;

• Dust accumulates in the air supply duct and is released during startup;

• The air outlet is improperly positioned and blows directly into the clean area.

During the inspection, the cleanliness of the air conditioning box and ducts, and the filter installation and sealing and replacement records should be confirmed. For filter seal inspection and filter status judgment, please refer to What should be checked when cleaning equipment is accepted? , learn how to check the installation status.

Dust release initiated after prolonged shutdown

When your air conditioner is shut down for an extended period of time, particles may accumulate inside and in the ducts. When restarting, the accumulated dust is carried out by the airflow and enters the clean area.

This situation is more common after seasonal switchovers or extended outages. During inspection you should pay attention to:

• Whether the pipeline is closed during shutdown;

• Whether cleaning or purging is performed before starting;

• Whether the particles increase significantly at the beginning of startup and then gradually decrease;

• Does the filter need to be replaced?

If the particles gradually stabilize after rising initially, it may be related to the release of dust. If it continues to be high, filtration and sealing issues should be investigated.

Interference of air conditioning airflow on local protection

Air conditioning supply may interfere with the airflow of local cleaning equipment. Common situations:

• The air outlet from the air conditioner blows directly into the workstation, deflecting the protective airflow;

• The air supply from the air conditioner meets the air from the workbench and forms a vortex;

• The return air position of the air conditioner changes the local air flow direction;

• The air volume of the air conditioner is too large, breaking the local protection boundary.

Open workstations and local protected areas are more susceptible to interference from air conditioning airflow. For lateral interference treatment in open workstations, please refer to How to establish a local clean area in an open workstation? . For the influence of supply air vortex, please refer to How does supply air vortex affect open workstations?。

Effect of temperature and humidity changes on particle measurement

When the air conditioner adjusts temperature and humidity, it may affect particle measurement:

• Humidity changes may affect instrument readings;

• Temperature changes may cause changes in airflow;

• Condensate may carry particles.

If the particle rise is synchronized with changes in temperature and humidity, you should confirm whether the instrument status and measurement conditions are stable. For the influence of changes in measurement conditions, please refer to How to choose particle counter sampling flow rate? , to understand the impact of instrument conditions on readings.

The synergistic relationship between air conditioning and cleaning systems

Air conditioning and cleaning systems need to work together. During inspection, you should confirm:

• Whether the air supply volume of the air conditioner affects the pressure difference in the clean area;

• Whether the return air from the air conditioner conflicts with the return air from the clean area;

• Whether the air conditioning filter section is coordinated with the clean system filter section;

• Whether the operation of air conditioning affects the working point of the clean system.

The air volumes of the two systems need to be balanced. If the air volume of the air conditioner is too large, it may interfere with the air supply path of the clean system. For calculation of clean area area and air supply demand, please refer to How to convert the clean area area into air supply demand? , understand the basic methods of air volume balance.

Suggestions for troubleshooting order

If the particles increase after the air conditioner is turned on, you can check in the following order:

• Confirm the correlation between particle changes and the start and stop of air conditioners;

• Check the cleanliness of the air conditioning box and ducts;

• Check the filter section seal and filter status;

• Check the position and direction of the air conditioning outlet;

• Check the impact of air conditioning airflow on workstation protection;

• Check the effect of changes in temperature and humidity on measurements;

• Check the air volume balance of air conditioning and cleaning systems.

Adjusting only one condition at a time and comparing particle changes will help determine the main cause. After the direction of the air-conditioning outlet is adjusted, the workstation protection boundary should be re-verified. It cannot be judged as qualified immediately after adjustment.

Project judgment example

Particles increased after the air conditioner was started in an open workstation. The investigation revealed that the air outlet from the air conditioner was blowing directly into the workstation, diverting the protective airflow. Adjustment method: Adjust the direction of the air outlet of the air conditioner and add a baffle on the side of the workstation. Particles restored after adjustment.

In another project, the particles increased after the air conditioner was started and continued to be high. The investigation found that dust accumulated in the air-conditioning box and was brought into the clean area after it was started. Adjustment method: Clean the air conditioning box and pipes, replace the filter section, and the particles return to normal after restarting.

These two situations indicate that the increase in particles after the air conditioner is turned on may be caused by air supply pollution or air flow interference, which needs to be investigated separately.

Key points for selection and acceptance inspection

Aili industrial equipment supporting support

The increase in particles after the air conditioner is turned on may be caused by air supply pollution or air flow interference. Aili Industrial has collaborative capabilities in fans, motors, filters, control systems and complete machine assembly links. It can cooperate in checking the air supply path, filter seal, air flow direction and system air volume balance during operation troubleshooting, helping to distinguish whether the source of particles is air conditioning supply, filter bypass or local air flow conflict, rather than judging the system to be normal based on temperature indicators only. 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。