What is a depyrogenation tunnel?
A depyrogenation tunnel is sterilizing equipment in the pharma industry. They used to remove pyrogens from glassware and containers for injectable manufacturing. It is largely used as a replacement for the sterilization system, where each item is sterilized in a Dry Heat sterilizer, requiring some time or a day to cool before being filled with containers.
Depyrogenation tunnels are largely used for the sterilization of glass containers that can be directly filled with product, without storing or holding. It is the part of the injectable line that consists of washing, depyrogenation tunnel and filling machine.
The depyrogenation tunnel sterilizes items at high temperatures like the Dry Heat Sterilizer - DHS. The difference is the technique for accomplishing the task. In the tunnel, items are placed on a belt through the feeding station, at a fixed rate. The speed of belt determines the sterilization time and is immediately set to match the sterilization time for a particular container
The feeding station is commonly connected to the washing machine that provides the continuous supply of washed containers to the tunnel
The inside of the tunnel is divided into different temperature zones, known as preheating, heating, and cooling.
● In the preheating zone, the temperature remains below the sterilization temperature to warm up the container. Warming - up the containers helps to protect containers against sudden temperature rise in the heating zone
● In the heating zone, the actual sterilization temperature is maintained.
● In the cooling zone, the temperature is lowered.
After the cooling zone, items are discharged from the tunnel through the outfeed station or side.
The outfeed of the depyrogenation tunnel is commonly connected to the filling machine to fill the product and further processing.
Some common parts of the depyrogenation tunnel include, but are not limited to, the following.
● HEPA filter
● Air Blower, to blow hot air to maintain high temperature
● Heaters - to heat the air inside the tunnel
● Conveyor belts - to move the items forward through different temperature zones
● Electronic components - different electronic components, such as PLC, HMI, sensors, VFDs, and airflow meters to control the operation of the depyrogenation tunnel
● Validation port- to perform the validation
Air blower generates a steady stream of airflow, which is heated by heaters to heat. A controller or a PLC is used to automate the entire process
HEPA filters are installed inside tunnels to filter out impurities from air. Because, the air comes in direct contact with the containers, and it is necessary to maintain the purity of the airflow.
Since the depyrogenation tunnel is often used with the washing machine at the infeed and the filling machine at the outfeed, there is a mechanism to synchronize these two machines with the operation of the depyrogenation tunnel.
● A sensor installed at in-feed synchronizes the washing machine's operation. It commands the main controller of the tunnel to start/stop if the washing machine starts/stops. Similarly, this sensor is also used to signal the washing machine to synchronize its operation.
● A sensor installed at the outfeed of the depyrogenation tunnel synchronizes the tunnel operations with the filling machine. Similarly, the filling machine synchronizes its operation with the tunnel through this sensor.
What can go wrong if an appropriate Depyrogenation tunnel is not selected?
Some problems that a machine buyer can face if they do not select an appropriate tunnel
● The process will not yield the required sterilization level
● The machine buyer will face capacity-related issues
● Frequent problems with the machine, keeping the machine in breakdown state
● Problems in tunnel operation
● Erratic behavior of sensors & instrumentation, making the process unreliable and dangerous
● Non-compliance with the regulatory regulations.
Some factors ...
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