What air equipment should be covered in daily inspections of clean areas?

Daily inspections of clean areas tend to stop at the level of 'whether the equipment is on or not.' Just because the power indicator light is on and the control panel display is normal, it does not mean that the air supply, return air and filtration are running effectively. The actual status of the air equipment needs to be checked separately from the terminal air supply, filter section, return and return air channels, control system and personnel and material channels.

The goal of daily inspections is to confirm that airflow paths and contamination isolation are maintained in a normal state, not just to confirm that the equipment is powered on. The following is expanded segment by segment according to the air path.

Create an inspection list based on system paths

The air system goes through many stages from air intake to exhaust. For daily inspection, you can create a list according to the air path and confirm it section by section:

• Air inlet and pretreatment section;

• Fan and air supply section;

• Filtration section (primary effect, medium effect, high efficiency);

• End air supply outlet or FFU/EFU;

• Return air channels and return air outlets;

• Exhaust and make-up air systems;

• Control and monitoring systems.

Inspection by route can help find problems that are easily missed by inspection at a single location. For example, the terminal equipment is operating normally, but the return air channel is blocked, and the actual circulation is still insufficient.

Terminal FFU and high-efficiency air supply vents

The terminal equipment is the last link for air to enter the clean area. Daily inspections should focus on:

• Whether the equipment operates as set and whether the speed or gear is normal;

• Whether the wind outlet surface is obviously blocked;

• Is the filter pressure difference within the normal range?

• Is there any abnormal vibration or noise;

• Check whether the installation seal is intact.

If the equipment operation indicator light is normal, it does not mean that the filter status is normal. Abnormal pressure differences, air volume drops, or sealing failures may not be reflected on the indicator light. FFU is running normally but there is dust problem at the work station. Please refer to The FFU is running normally, why is dust falling at the workstation?。

Filter segments and filter status

The filtration section includes primary, medium and high efficiency filters. Daily inspections should focus on:

• Changes in pressure difference across filters at all levels;

• Whether the filter is damaged, damp or displaced;

• Whether the installation seal is intact;

• Replacement records and maintenance intervals.

Filter resistance will increase with dust accumulation, and pressure difference changes are an important basis for judging maintenance needs. For the judgment method of initial resistance and final resistance, please refer to What are the initial resistance and final resistance used to judge?。

Return air channel and return air outlet

The return and return air ducts are paths for air circulation. Daily inspections should focus on:

• Whether the return air outlet is blocked by equipment, shelves or materials;

• Whether there is dust or foreign objects in the return air duct;

• Whether the air supply is short-circuited and whether the air passes through the workstation;

• Is the room pressure difference stable?

Obstructed return air ducts are a common problem and can result in airflow short circuits or localized stagnation. For troubleshooting methods of airflow short circuit, please refer to What particle problems can airflow short circuits cause? , for the treatment of local retention, please refer to How to reduce local retention in non-unidirectional flow clean rooms?。

Exhaust and make-up air equipment

Exhaust and make-up air equipment affect room pressure difference and air flow direction. Daily inspections should focus on:

• Whether the exhaust equipment operates as set;

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

• Whether the direction of room pressure difference is stable;

• Is the exhaust vent blocked or dusty?

Changes in exhaust air may cause differential pressure fluctuations, which in turn affects the direction of airflow. For specific balancing methods, please refer to How to convert the clean area area into air supply demand?。

Control systems and monitoring equipment

The control system manages equipment operation, speed regulation and linkage. Daily inspections should focus on:

• Is the control panel display normal?

• Whether the sensor and differential pressure gauge readings are stable;

• Check whether there are any abnormalities in the alarm record;

• Is the linkage logic normal?

Readings from monitoring equipment should be consistent with actual conditions. If the display is normal but the actual air volume is insufficient, on-site measurement is required to confirm. For partition management of multiple devices, please refer to FFU group control system。

Personnel and material passages and isolation facilities

In addition to air equipment, personnel and material passages also affect the clean area environment. Daily inspections should focus on:

• Whether the door is closed normally;

• Whether interlocking and air shower equipment are operating normally;

• Whether the transfer window and material channel are sealed;

• Whether personnel enter and exit according to prescribed procedures.

If channel management is not in place, external pollution will continue to enter and the burden on air equipment will increase. For the impact of personnel entry on particles, please refer to How to locate the cause of increased particle number after personnel enter?。

Log changes and correlate production events

Routine inspections are more than just ticking boxes, they should also record changes. include:

• Changes in equipment operating parameters;

• pressure differential and wind speed changes;

• Filter replacement and maintenance records;

• changes in production schedules and personnel;

• The time and location of the exception.

Correlating changes with production events can help determine whether the problem is a change in equipment status or a change in operating conditions. For the impact after startup of process equipment, please refer to What should I do if the cleanliness of the process equipment drops after it is started?。

Project judgment example

A certain project inspection found that a group of FFUs were online, but the return air channel was occupied by packaging boxes. Adjustment method: Clean the return air channel and check the particles in the relevant area instead of just recording that the equipment is normal. Airflow in the area is restored after cleaning.

Another project inspection found that the pressure difference of the filter continued to rise, but it was not replaced in time. Adjustment method: Schedule maintenance according to the pressure difference and operating time, and review the air volume and sealing after replacement. The system status is restored after adjustment.

These two situations illustrate that daily inspections should cover all aspects of the air system and focus on actual air flow and filtration status, rather than just confirming that the equipment is powered on.

Key points for selection and acceptance inspection

Aili industrial equipment supporting support

Routine inspections should cover all aspects of the air system, not just terminal equipment. Aili Industrial has collaborative capabilities in fans, motors, filters, control systems and complete machine assembly links. It can check the corresponding inspection points of terminal equipment, filter sections, air supply and return channels and control systems according to the air flow path and maintenance requirements of the project, help establish an inspection list covering the complete path, and timely identify changes in air volume, pressure difference and filtration status.