Article: Combining Containment Strategies

In some cases using multiple containment strategies in a single piece of equipment is best to suit the pharmaceutical process. The Weighing Isolator described below is designed to provide complete operator and environmental protection during weighing and sub-dividing of highly potent powders in a pharmaceutical warehouse. The key process constraint in this design is that (5) different API's can be weighed & sub-divided within an 8 hr work day, with 100% validated CIP cleaning between each weigh.

The isolator system is of fully welded 7 gauge 316L stainless steel construction, with 5/8 inch corner radiuses, and laminated safety glass. It operates in a negative pressure mode with HEPA filtered turbulent airflow. The inlet and outlet HEPA filters are "push-push" type with safe change ability. Negative pressure inside the isolator is provided by a blower with a variable frequency drive maintained by an Allen Bradley MicroLogix control system.

Transfer of the compounds in and out of the isolator system is critical in this process. A large bagging ring located on the rear wall of the isolator is used to introduce and seal large drums of powder to the isolator. Moving weighed and sub divided powders from the isolator is done via a 270mm RTP system on the side wall and a split butterfly valve through the floor and into a lower pack-off booth without breaking containment. A Spray nozzle arrangement inside the isolator allows for 100% cleanability & drying without operator intervention. Waste liquid exits the isolator via a diaphragm drain valve.