High containment control

Applied Containment Engineering, a leading supplier of specialist barrier/isolation systems based in Dewsbury in the UK, recently undertook a multi-isolator project for a US company. The installation involved product sampling and offloading from a filter dryer, sub-division and sampling of active and excipient material, dispensing, reactor charging and material transfer to and from kegs. The individual processes and transfers between them including clean-down operations, required an OEL of less than 300ng/m3. The series of purpose-designed isolators with transfer technology formed the basis of the containment solution. All systems had to be compatible but specific to each individual operation and process. A purpose designed isolator system for product off-loading, sampling and heel removal from a Comber filter dryer was built. The design of the isolator and the control interface also enabled the operations to take place at the isolator by incorporating duplicate controls into the isolator local control panel. Safety interlocks were provided, with signals back to the Comber control system. The double chamber design of the Isolator with a rapid transfer port (RTP) access to the lower chamber allowed for contained charging of drums. As the isolator internal environment was inert using nitrogen, monitored by oxygen sensors, the safety interlocks allowed for purging of nitrogen from the unloading chamber only, enabling removal/replacement of sealed drums. The Sub-Division was combined with the dispensary operations contained within a triple chamber isolator, consisting of the loading, dispensary and unloading chamber. The loading chamber was furnished with a pneumatic drum carriage to allow the drum to be over-bagged and sealed to the rear of the dispensary chamber. In effect, this is extended the dispensary chamber into the loading chamber without compromising either chamber condition. The main chamber allowed for the product to be weighed out and charged into a keg through an RTP, separating the main chamber from the unloading chamber. Material can be introduced to the dispensary chamber via a dedicated RTP, ergonomically positioned to allow the bagged material to be connected and charged. A weigh platform was also provided internally with the display and alphanumeric key panel housed externally, thereby minimising congestion and reducing the size of the internal chamber. As the internal environments are inert, oxygen monitoring was provided to ensure the internal atmosphere was purged with air before opening. In additional, the system displaces nitrogen with a minimum 18% oxygen once the stop button has been pressed. The requirement for the reactor charging as with most reactors was for access and intervention, therefore anything proposed had to be either mobile or easily removable. By utilising the RTP bag technology a smaller single chamber reactor charging isolator was designed. This contained a product charging RTP in the roof of the isolator, a sample transfer RTP on the side, a reactor sampling spigot in the isolator, and a chute to connect to the reactor. As this type of unit needed to be removable, a mobile station was designed to house the HVAC, controls and instrumentation. The design was such that the isolator could be positioned on the mobile station and wheeled into location. The isolator can be lifted from its mobile station and connected to the reactor. Site trials of the equipment supplied were carried out using sodium bicarbonate for technician training while surrogate testing was done using Naproxen sodium with a containment level well below 100ng/m3. Paul Richards, senior research engineer at Pfizer global research and development said " The Isolation systems were designed for our specific applications through innovative engineering, a flexible approach to design, and customer focus".

This article was previously published in Manufacturing Chemist magazine

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