What is a Pass Box? Effective maintenance of Pass Box

In cleanrooms, cleanliness standards are always paramount. When moving products from outside into the cleanroom environment, Pass Boxes are used for transportation. So, what is a Pass Box? The structure, operating principles of the Pass Box? What should be noted in the maintenance of Pass Box? Let’s find out with INTECH Service in the article below!

What is a Pass Box?

The Pass Box is a specialized device used to transfer goods, finished products, or small items between cleanrooms with different cleanliness levels or from the outside environment into the cleanroom. Using Pass Box  helps limit the number of times cleanroom doors are opened, minimizes cross-contamination between areas with different cleanliness levels, saves energy, and maintains HVAC systems.

Pass Boxes are designed as a door system, with electrically or mechanically interlocking locks, allowing only one door to be opened at a time, ensuring complete isolation of the cleanroom environment from the outside environment or areas with different cleanliness levels. Products placed in the Pass Box are cleaned of dust using ultraviolet rays to blow away the dust and filtered through HEPA filters.

pass box la gi

Pass Box is commonly used in fields such as pharmaceuticals, cosmetics, electronics, and healthcare.

Pass box structure

The structure of the Pass Box depends on customer requirements. Typically, a Pass Box will have the following main components:

Frame material made of electrostatically painted steel or high-quality 304 stainless steel.

Toughened glass door creating a smooth, shiny surface, allowing visibility inside, enhancing aesthetics, and ensuring safety for users.

Smart interlocking lock system with pneumatic or electromagnetic locks to minimize cross-contamination into the cleanroom area, ensuring safety for users.

Air filter membrane: HEPA filters effectively filter out 0.3-micron dust particles with a filtration efficiency of 99.99%, ensuring compliance with cleanroom standards.

Air spray nozzles equipped with high-velocity air speeds ranging from 20-33m/s, ensuring effective friction necessary for removing airborne pollutants.

For Pass Boxes with UV germicidal lamps, when the door is closed, the UV lamp automatically activates to sterilize, preventing bacteria from entering the cleanroom, ensuring safety for users.

cau tao pass box 1

Operating principle of Pass box

The cleanroom Pass Box has two symmetrical doors, the rear door and the front door. These doors operate on the interlock principle – interlocking locks (only one door can be opened at a time).

When one door is opened, the remaining door latch will automatically lock thanks to the interlocking lock system. The Pass Box blows away dust adhering to the goods or objects, and the dust is sucked into the bottom of the box. This ensures that dirt from goods or objects from the outside does not contaminate the cleanroom.

Classification of Pass Box

Usually, Pass Boxes can be classified into 2 main types, Static Pass Box and Dynamic Pass Box.

Static Pass Box

Static Pass Box is used to meet the basic transportation needs between two rooms with equivalent cleanliness levels to minimize human traffic.

Static Pass Box is also called the standard cleanroom transfer box or standard Pass Box. Depending on the interlocking door feature, Static Pass Box has two types: mechanical interlocking lock and electronic interlocking lock.

Dynamic Pass Box

Dynamic Pass Box is a type of Pass Box used to transport items from an unclean environment to a clean environment.

Dynamic Pass Box is also called self-cleaning cleanroom transfer box, self-cleaning Pass Box.

pass box dong 1

pass box dong 2

Dynamic Pass Box can be classified according to the interlocking form similar to Static Pass Box, which is mechanical interlocking lock and electronic interlocking lock. However, Dynamic Pass Box also has another classification based on usage, which is Air Shower Pass Box and laminar flow Pass Box.

cac loai pass

Air Shower Pass Box: Equipped with additional spray nozzles to blow away dust adhering to the surface of objects.

Laminar flow Pass Box: The laminar flow Pass Bx generates laminar flow air (vertical airflow) with extremely high cleanliness to filter out dirt from goods when they are placed inside, meeting the high requirements of cleanrooms.

Notes when using Pass Box

A separate path should be designed for transporting goods. Do not transport them on the same path as people.

Goods need to be transferred to intermediate stations before being transferred into the cleanroom. The process of removing them from the cleanroom should be similar.

During the use of the pass box, absolutely do not open both doors at the same time.

Open the outside door to introduce materials, then open the inside door to receive the goods.

After daily use, thorough cleaning with disinfectant is necessary.

luu y su dung pass

Effective maintenance of Pass Box

Pass Box is a device that rarely malfunctions, so maintenance work does not require much attention. However, attention should be paid to the following activities:

Regularly check whether the interlocking function operates correctly. If not, contact the manufacturer or a technical specialist for repair and prepare methods to ensure cleanliness for the room.

Calculate and check if the UV lamp is working properly. If not, it needs to be replaced promptly (typically UV lamps only operate for a maximum of 4000 hours).

For Dynamic Pass Box, special attention should be paid to maintaining and servicing filters. For coarse filters (usually G4), they need to be replaced every 6 months. HEPA filters need to be replaced every 6 – 12 months.

Additionally, filters may become damaged at any time, so we need to monitor the pressure differential gauge to determine if the filters are working properly. If it does not match the pressure difference level, the likelihood of filter damage is very high and needs to be addressed immediately.

Above are the information about the definition, structure, operating principle as well as instructions for effective maintenance of Pass Box. If you have any further questions or need assistance, please contact INTECH Service for detailed advice!