Pass box for clean room

What is pass box? – Pass box for clean room

Pass box is must-have equipment for clean areas. This article will provide the basics of pass box: what is pass box, pass box structure, the role of pass box for clean room,…Let’s find out!

1. What is pass box? 

Pass box ( or pass through box, pass through chamber or transfer hatch) is one kind of facility, which is located on partition walls of clean room. Its function shall be a buffer area for transferring goods and materials between inside and outside of cleanroom. 

2. Why pass box is necessary for clean room?

Cleanroom is a controlled environment. The elements are monitored, including the quantity and size of particles, humidity, temperature, etc. Opening doors too much may cause the loss of pressure and air cleanliness of the cleanroom. This is why we need pass box for clean room.

Pass box can prevent any disturbance of airflow and air pressure in clean room, which can be caused by the door opening for goods transferring. Moreover, it can reduce the personnel movement between rooms, preventing dust from entering the cleanroom

Pass box for clean room is equipped with UV light which is used for bacteria control.

Pass box is provided with two interlocked doors. It works as follows: when one door is open, the other door cannot be opened. This way prevents direct contact between the connected areas.

pass box clean room

pass box clean room

3. How many types of pass box for clean room? 

On the market now, there are wide ranges of pass boxes for particular uses.

(Some special pass box designs will be customized based on customer’s request)

  • According to interlocking system, pass boxes are classified into 2 types: mechanical interlocking pass box and electronic interlocking pass box
  • According to use purpose, the pass box for clean room is divided into two types: static pass box and dynamic (self-clean) pass box

The classification is common, let’s deep dive into 2 types of pass boxes.

3.1. Static pass box

Static pass box is a kind of pass box used to transfer items and materials into cleanroom. It is mainly installed between clean areas. For example, a static pass box is placed between cleanroom class D and cleanroom class C.

Static pass box

Static pass box structure

A static pass box includes body, doors, interlocking system, UV light

static pass box drawing

  static pass box drawing

Body: The body of the pass through box consists of the housing and the chamber.

The chamber is made of 304 stainless steel, while the housing can be made of 304 stainless steel or powder-coated steel, etc.

Door: Two doors are equipped with tempered glass windows sealed by durable feather edge rubber for airtightness.

Interlock system: There are 2 types of interlock for static pass box: mechanical interlock system and electronic interlock system.

UV light: UV light is employed inside pass box for sterilization of materials and items

pass box uv light

  pass box uv light

Static pass box working principle 

Static pass box use UV light to disinfect transferred materials. The interlock system works by ensuring two doors don’t open at the same time. This prevents the risk of cross-contamination in clean rooms.

Static pass box specification

WxDxHCustomer request
InterlockMechanical / Electronic
HousingStainless steel / Powder coated steel
UV light1x8W
HingeStainless steel
Additional accessoriesAlarm, Fingerprint,…

3.2. Dynamic pass box

Dynamic pass box (or dynamic pass-through) is known as the self-cleaning pass box, which allows materials and items to be transferred into cleanroom without actual personnel movement. It can be used between cleanrooms, but mainly installed between cleanroom and non-cleanroom.

For example, a dynamic pass box is placed between the non-BSL area and the BSL- 2 area.

Dynamic Pass box

Dynamic pass box structure 

Dynamic pass box includes body, doors, interlock system, UV lamps, HEPA filter, fan and differential pressure gauge.

dynamic pass box drawing

  dynamic pass box drawing

(1) Differential pressure gauge; (2) DOP/PAO test port; (3) Control display; (4) Door handle; (5)Interlocksystem; (6) Pre-filter; (7) Hepa filter; (8) UV lamp.

Fan: It sucks the air and blows it through HEPA filter. The clean air will go into the chamber to sterilize the objects

Pre-filter: G4 filter is used to remove large particles (Some pass box design does not have pre-filter)

HEPA filter :H13 or H14 filter with filtration efficiency up to 99.995% is widely used in dynamic pass box

DOP/PAO test port: DOP/PAO Test Port is available for HEPA Filter leak test and particle count.

Differential pressure gauge: It is used to check the pressure drop of HEPA filter

Dynamic pass box working principle

The air is sucked by a centrifugal fan then passed through HEPA filter. The dust and bacteria is trapped by the filter. Then the filtered air enters the working zone at a uniform flow, creating a clean working zone.

Read more: How does dynamic pass box work? 

Dynamic pass box specification 

WxDxHCustomer request
HousingStainless steel
UV light1x8W
HEPA filterH13 / H14
Differential pressure gauge0-500 pa
Dynamic pass box specification

3.3. The difference between static pass box and dynamic pass box

The outstanding difference between dynamic pass box and static pass box is that dynamic pass box has self-cleaning properties, while static pass box does not. 

Dynamic pass box is equipped with a HEPA filter with an efficiency of 99.99% at around 0.3 microns. A static pass box doesn’t have a filter. The dynamic pass box also has a differential pressure gauge ranging from 0 to 500 pa. It is also equipped with a motor fan for blowing out dust particles.

The static pass box just has an air-lock system to prevent ambient air from entering or clean air from disappearing from the cleanroom.

4. Pass box application 

Pass box is necessary for cleanrooms. Pass box is applied in any industry that needs cleanrooms, such as pharma cleanrooms, electronic cleanrooms, food processing cleanrooms, operating theatre of hospital, (microbiology/radiology/…) laboratories, etc.

5. Pass box price 

“How much is a pass box?” is the question VCR receive most. The price of pass box depends on many elements. There are 4 main factors determining the price of a pass box:pass box types, pass box dimension, material and accessories. 

Pass box types

The type of pass box determines much on the price. For example, dynamic pass box price is higher than the static pass box.

Pass box dimension

That is obvious! The bigger the pass box is, the higher the price is!
pass box cleanroom


Material is one of the main factors affecting the price of pass box. Pass box material available on the market can be powder-coated steel, sus 201 stainless steel, sus 304 stainless steel. The most popular option of most cleanroom contractors is Sus 304 stainless steel pass box. Sus 304 stainless steel is corrosion-resistant and has strong performance stability. The value determines the price. Therefore, sus 304 stainless steel pass box is more expensive than the others.


The accessories of the pass box also affect the price. Take the interlocking system. Pass box with mechanical interlock is cheaper than a pass box with an electronic interlock.

6. Pass box guidelines 

6.1. Static pass box guidelines 

Here are the operation guidelines for static pass box:

Step 1: Connect the pass box to the power supply

Step 2: Before using pass box, the pass box needs to be cleaned with 70% IsoPropyl Alcohol. Make sure interlock system and UV light is working properly

Step 3: Open the door to put the items to be delivered into the pass box. The other door are forcibly closed.

After the items are laid inside,  immediately close the door.

Step 4: Turn on the to sterilize the items, then the other door can be opened and the items are ready to pick up.

pass box guidelines

6.2. Dynamic pass box guidelines 

Step 1: Make sure that pass box is connected to the power supply

Step 2: Clean the dynamic pass box with 70% IsoPropyl Alcohol.

Step 3: Check the working performance of interlock system and UV light

Switch ON the pass box from the electric board to start the light, and the fan.

Check the reading on the differential pressure gauge, ensuring that the value should be within the range of 80 to 150pa.

Step 4: Open the door to load the items. Then, close the door immediately.

The items are kept inside under the exposure of UV light for about 15 – 30 minutes.

Step 5: After the items are sterilized, open the other door to unload.

Make sure that the operator closes the door immediately after taking the items away, so as not to affect the next delivery.

At Vietnam Cleanroom Equipment, our team knows how to help you find the right pass box for your needs. Get a quote for pass box cost and know exactly what to expect – contact us today via hotline +84 90 123 7008 / +84 90 123 9008

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 – biosafety cabinet, and other equipment

For details, please refer to Vietnam cleanroom equipment official website

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