Pass box is tool used in the pharmaceutical industry as part of the clean room system. Pass box is used to transfer the material between two areas generally between the clean room area with same classified area or the controlled area and an the unclassified area. There are two types of pass box used in the pharmaceutical industry.
Purpose of the pass box
- To prevent the contamination and cross-contamination of the material
- To maintain the cleanliness and requirement of the clean area for the manufacturing activity and testing
- To prevent the microbial contamination of the product and the also environment where manufacturing activities are going on.
- Pass box is used to transfer the material from lower cleanliness area to higher cleanliness area or vice-versa in the classified area and also known as the hatch. Pass box works as a barrier between two cleanliness level areas.
- Pass boxes are used to transfer material for blending, granulation or sterilization in the manufacturing area and sterilization & incubation in the microbiology laboratory
- In some cases, equipment parts are also transferred through the pass boxes in sterile manufacturing areas.
Pass boxes help to prevent the air flow from one area to another while transferring the material. One door of the pass box opens at a time and both the doors cannot be opened simultaneously. There should be an interlocking system in the pass boxes.
Types of the pass box are used in Industry
Pass boxes are of two types - A) Dynamic Pass box B) Static Pass box
A. Dynamic Pass box:
- Dynamic pass box works like an airlock or Laminar Air Flow unit. Clean air enters in the pass box and prevents the entrance of the contamination. Dynamic pass boxes may be Cascade, Sink or Bubble type similar to the airlocks in pharmaceuticals.
- Static pass boxes are simple boxes mounted between two areas and also known as passive pass boxes. The area having higher cleanliness level shall have the higher pressure that helps to prevent the entrance of contamination in the sterile area.
- Ultra-violet light is also installed in the pass boxes to remove the contamination that may enter during the transfer of material. It should be replaced after 1000 burning hours. Pass boxes should be cleaned with disinfectants at regular intervals.
- The efficiency of the pass boxes should be verified by validation. Validation may be done by exposing the known population of the bacterial culture.
Difference Between Dynamic and Static Pass Box
The pass boxes have similar features such as having a mechanical interlocking for the doors, UV lights, and fluorescent lamps and are both made of the same material which is stainless steel. However, with all the similar features, there are several differences between the two types of pass boxes as they are described below.
- Static pass boxes are known to transfer materials between two clean environments which are equally clean and are designed to work with minimal personnel movement while dynamic pass boxes are used to pass through materials from an uncontrolled environment to a controlled environment. A static pass box should never be used to transfer material between a clean room and a non-clean room.
- A dynamic pass box is a cubicle box which has got interlocked doors located on both sides. This protects the controlled environment from being polluted while the transfer of material is taking place inside. A static pass box, on the other hand, has got an electromagnetic interlocking arrangement which is located between the two doors. The arrangement is fitted with an LED indicator which helps to show whether any door is open.
- A Dynamic Pass Box has got a system known as an Interlock Guard which helps to control both the outlet and the inlet so that there is no time that the two are opened. Due to this, dirt and other loose particles are removed from the materials being transferred to the manufacturing area and vice-versa but a Static Pass Box doesn't have such a feature since it only transfers material between two equally clean environments.
- A Dynamic Pass Box is fitted with a suction filter of around 0.3 microns that is a stainless steel product and a supply filter of about 10 microns that is made of aluminum. A Static Pass Box doesn't have the filters. The Dynamic Pass Box also has a pressure gauge ranging from 0 to 25 mmwc. It is also fitted with a motor blower of 1/5 hp for blowing out dust particles. The Static Pass Box is designed as an air-lock device to prevent ambient air from entering or clean air from disappearing from the clean room.
- For a Dynamic Pass Box, the Ultraviolet light's specifications are 18 Watts while that of a Static Pass Box is 8 Watts. The Ultraviolet light with hour meter is controlled by the interlocking arrangement and it goes off whenever any of the doors open.
- The Fluorescent lamp in a Static Pass Box is about 40 Watts while that of a Dynamic Pass Box is about 20 Watts. The lamp is controlled by the interlocking arrangement and when the doors are in a closed position, the lamp is on.
ALSO READ: Types of Airlock used in Pharmaceutical
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