Material transfer during the manufacturing operation is necessary, and care is taken not to disturb the area and environmental parameters. However, since humans are involved in material transfer, it often becomes challenging to maintain these parameters.
The pharma industry uses various process and equipment to enable humans transfer material without disturbing environmental conditions, and pass through is one of many.
What are Pass Throughs?
Pass-through boxes are mechanical enclosures that facilitate materials & Items transfer in and out of two areas without affecting the area inside. They prevent disturbance in the area parameters such as airflow and purity during material transfer.
The main reason for their usage in the pharma industry is because, during manufacturing, it is not recommended and allowed to use doors or regular entry points for transferring material in and out of the area. Instead, a dedicated opening and pass-through equipment are used to transfer them. They are designed and manufactured according to the equipment, items, and accessories to be moved.
The transferring area can be of the same class, purity level, or different. However, it is also case different class areas require material transfer
Pass through consist of two doors are two sides. They are installed at that side of the wall location where material transfer is required. One opening is on the critical side, while others are on the non-critical side. The doors at both openings cannot be opened simultaneously, thereby preventing exposure of the dirty side to the clean side.
They are sealed at every point to prevent cross-leakage & contamination and provide separation between two areas.
Another purpose of pass-through is to act as a barrier between critical and less necessary areas, effectively preventing damage to the crucial area's environmental parameters.
Types of pass-throughs
Two common types of pass-throughs are used in the pharmaceutical industry - static and dynamic. Let's discuss briefly each of these.
Static Pass-throughs
Static pass-throughs transfer items between areas of the same classification or purity level. Their design and construction are less complex, with no filters and interlocking, since they do not require strict control.
Dynamic Pass-throughs
Dynamic pass-throughs transfer items between different classification area, such as clean areas and corridor. They are built to prevent disturbance in the environmental parameters since the other side of the pass-through is of lower air quality.
An important feature of dynamic pass-through is door interlocking, which helps prevent the opening of both side doors. The interlocking can be mechanical or automated.
In mechanical interlock, the door is mechanically designed in a way that allows only one door to be opened.
In automated interlocks, electromagnetic locks do not allow a door to be opened if the opposite side of the door is opened. The door opening and closing are sensed using various sensors that can sense if a door is closed or open, and a corresponding lock is controlled through electronics means
Door interlocking prevents accidentally opening both doors simultaneously, contaminating the clean side with less classified area.
The design and construction of dynamic pass-throughs are more complex than static pass-throughs. Some additional components present in the dynamic include, but are not limited to
Filters are installed at supply and suction to filter the air into the pass-throughs. Because, air is used to shower the material inside before the discharge side door is opened for off-loading, to remove any impurities from them. HEPA filters can also be used depending on the process and area requirement.
UV Light - UV light can also be added to disinfect the items inside before being transferred from one side to another
Blower Fan - A small blower to blow filtered air into the chamber
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