I. What is dynamic pass box?

Pass box is also called pass-through box or transfer hatch. A dynamic pass box is used as a piece of auxiliary equipment in the cleanroom. Dynamic pass boxes are used for the transfer of small items to reduce the door openings of the clean area and the non-clean area or between cleanrooms of different cleanliness levels, thus greatly reduce the pollution of the clean area.

II. Dynamic pass box maintenance and repair guide

Dynamic pass boxes are machines, and like any machine they need maintenance. Here are the dynamic pass box repair and maintenance guides:

1. According to the cleanliness of the environment, the filter should be replaced regularly (the pre-filter should be replaced from 1 to 6 months, and the HEPA filter should be replaced from 6 to 12 months), and the machine should be shut down during replacement.

2. Regularly (usually once every 2 months) use a particle counter to measure the cleanliness of the cleanliness area where this product is used to purify. If the measured cleanliness does not match the required cleanliness, the reason should be investigated (whether there is leakage, etc.) If the HEPA filter is worn, you should replace it with the new filter.

3. Sterilize the area regularly (usually a week). Especially, wipe the surface and UV lamp with gauze moistened with solvents such as alcohol or acetone to keep the surface clean.

4. When replacing the HEPA filter, the dynamic pass box opens the air outlet orifice. When replacing, pay attention to the arrow on the filter pointing to the laminar airflow direction.

5. After replacing the HEPA filter, use a laser particle counter to check whether the sealing of the frame is good, adjust the fan speed to keep the average air velocity in the operating area within the range of 0.3m/s to 0.6m/s, and then use laser particles counter checks the cleanliness.

6. Dynamic pass box only needs to be plugged in the power cord, and the equipment is on. When maintaining and repairing the equipment, be sure to unplug the power cord and confirm that the power is off before proceeding.

7. Non-professionals are strictly prohibited from touching the circuit board or adjusting the potentiometer of the pass box.

8. The differential pressure gauge is sensitive to temperature and grid voltage, and it needs to be used correctly for correct measurement.

9. When the differential pressure in the pass box is abnormal, wait for the fan to stop completely, restart the pass box and perform a self-check. At this time, it may automatically return to normal.

10. When replacing the HEPA filter, pay attention to the following things:

  • When replacing the HEPA filter, pay special attention to unpacking, handling, installation to ensure that the filter sheet is intact and undamaged. It is forbidden to touch the filter sheet.
  • Before installation, point the new HEPA filter to a bright place and see with the naked eye whether there are leaks in the HEPA filter caused by transportation. If there are leaks, the filters cannot be used.
  • When replacing the filter, the inspection panel should be removed first, then the bead, and then the filter should be taken out and replaced with a new one (note that the arrow mark should be in line with the airflow of the purification unit when replacing the HEPA filter), and install the pressure strip and the inspection panel according to the steps.


Vietnam Cleanroom Equipment (VCR) specializes in providing cleanroom equipment for construction contractors.

We provide high-quality products with competitive prices and large quantities nationwide. The equipment includes:

Differential pressure gauge, FFU Fan Filter Unit, Pass box, Clean room air filter, HEPA box, Clean booth, cleanroom steel door, Isolator cabinet, and other equipment