The HEPA box is an ideal terminal filter device, which is widely used in medicine, health, electronics, chemical, and other industries. In order to verify whether HEPA can meet the cleanliness requirements, it is necessary to test the cleanroom

I. Check the cleanliness

1. In today's advanced technology, it can be detected quickly with some more sophisticated testing instruments.

2. The detection method of the device uses active sampling and passive sampling.

Active sampling adopts the filtering method and impact method.

The filtration method allows a certain amount of air to pass through an analytical filter.

3. Impact method, you can use Anderson sampler, Root centrifugal sampler, slit sampler.

Passive sampling adopts the falling method. Use the principle of spreading suspended particles in an open agar plate.

II. Test

1. Clean air can be obtained through the circulating fan of the clean air conditioner, through the HEPA filter, the medium-efficiency filter, and the pre-efficiency air filter, with different cleanliness and different wind directions. Some fresh air must be added through the new air outlet.

2. The airflow hood can be directly aimed at the nozzle for one-time measurement and direct measurement. If your nozzle has many small holes (to make the air volume uniform) and a grille, your anemometer should be kept 3-5 cm away from the nozzle. If you use a hot anemometer, try to face the gap. Don't use the grid, the grid method is measured and averaged. The same section can be measured.

3. It can be measured at multiple points where the distance from the tuyere is 2 times the width of the diffuser.

The measuring point should be the same as the grid and the wind speed can be averaged. These vents are all about the same size.

Use tinplate or even plastic plates to make a bucket slightly larger than the section of the tuyere, and then cover the tuyere when measuring, and then use an anemometer to measure the nozzle of the bucket at multiple points and calculate the average value.

III. Maintenance points

Replacing the air filter inside within a certain period of time is the main point of maintenance. Cleanroom needs to be installed with HEPA box.

The joint between the flanging of the air outlet and the ceiling plate is sealed.

Remember that the cracks must be strictly handled.

Do not install the device if the device is damaged or the coating is damaged. The installation and the air duct must be strictly connected, and the open end shall be reinforced with plastic film and tape for airtight treatment.


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

For details, please refer to Vietnam cleanroom equipment official website