UNIT OPERATION / PRODUCTION PROCESS


Pack-off Booths

These are packaging systems that answer demands of primary and secondary levels of containment for materials off-loading and discharge processes. They may be stand-alone for packaging or integrated into other processes such as milling and dispensing.

The design of pack-off booths is highly dependent on the requirements of product protection, personnel exposure and environment control that is specific to the pharmaceutical or chemical industry. Materials can be transferred from almost any receptacle (i.e. drum, big bag, container, intermediate bulk container, process equipment) and over long distances which account for the flexibility in the design of the pack-off system.

The following are various pack-off booth features that may be incorporated into the packaging system:

• Packing Heads

They are primarily used for transfer of materials to drums without liners. The packing head is normally suspended on a frame above the load platform and includes a downward inflatable ring that forms a seal when inflated against the rim of the drum. It is therefore important to consider the weight of the packing head and support frame in designing the system. The feed chute and the suspended packing head must also be connected via a flexible assembly. Packing head configurations are available to fit a range of 150mm to over 600mm diameter container.

A downward inflatable seal (Figure 1) achieves primary containment of particulates. The seal is kept into contact with the rim of the drum. Upon filling of the drum, the feed valve will close and the seal will deflate. This will allow the drum to be pulled off the filling point and its lid can be fitted in front of or on the side of the inflatable seal (IChemE, 2002).

  • Requirements: The device should be enclosed within a horizontal laminar flow booth to allow continuous capture of particulates that may escape during opening or closing of the inflatable seal.
  • Application: This may be applied to any unloading process where dry or wet solids are packed into drums without polyethylene or similar impervious liners.
  • Scale of Operation: kilograms/tons

Figure 1. Operating principle of packing heads

• Packing Seals

Can be used for material transfer on drums with liners. The drum to be filled rests on a weighing platform and its inner lining is sealed to a filter pipe via an outward-inflating seal device. A pair of concentric filler or exhaust pipes or a small-bore exhaust connection is used to load powder into the drum and capture the displaced air (IChemE, 2002).

Figure 2. Operating principle of packing seals

  • Requirements: The device should be enclosed within a horizontal laminar flow booth to allow continuous capture of particulates that may escape during opening or closing of the inflatable seal.
  • Application: This may be applied to any unloading process where dry or wet solids are packed into drums fitted with polyethylene or similar impervious liners. Aside from drums, both packing head and packing seals may be applied for kegs and intermediate bulk containers (IBCs).
  • Configurations: Sealing configurations include outward inflating, downward inflating and inward inflating (Figure 3).
    • Outward inflating seal– achieves a clean and dust-tight seal within the open mouth or inner surface of the container, applied on continuous-lining or single-lined containers
    • Downward inflating seal – a seal is formed upon the downward inflation of a membrane against the top of unlined drums or inlet rim of intermediate bulk containers (IBCs)
    • Inward inflating seal – a continuous liner is compressed against the feed tube not allowing product contact with the natural rubber seal; ensures a clean dust tight seal
  • Scale of Operation: kilograms/tons

Figure 3. Sealing configurations for Pack-off Booths

• Negative Pressure Glovebox Units

These are negative pressure units which allow contained dispensing of materials from bags. The negative pressure is created by air suction of exhaust fan from the supply air filtered by HEPA H14 filter. The inclusion of a glove box isolator in a pack-off booth provides secondary level of containment that ensures product integrity and personnel protection.

  • Requirements: The glovebox units require a unidirectional airflow at a constant negative pressure of around -30Pa
  • Application: Aside from pack-off, negative pressure glovebox units are also used in dispensing, weighing and acquisition, assembly and product transfer.
  • Scale of Operation: grams to kilograms

Research Laboratory University Science Development Glovebox Sun Bright Room Advanced Complex Equipment

• Gas Management System

These are usually incorporated into glovebox units when the product or the production process requires protection from oxygen, moisture and other substances. A high purity nitrogen or argon atmosphere is maintained inside the box. In special cases, depending on the necessity of the production, other gases such as helium, sulfur hexafluoride or gas mixtures with carbon dioxide are used. Contaminant residual concentration is continuously maintained below 1 part per million (ppm).

• Balances and Moisture Analyzers

Analytical, top loader or bench scale balances used for weighing of powders and moisture analyzers may be brought into an isolated pack-off booth or may be intrinsic to the pack-off system.

• Solvent/ Liquid Drum Booths

Specialized pack-off booths for drum to drum or drum to process transfer and handling of solvents or liquids. They can provide low ppm containment as required by the method.

 

Secondary Containment Systems That Include Pack-off Booths

The pack-off booth itself may be incorporated within secondary containment systems such as downflow booths, laminar flow cabinets and containment isolators:

• Downflow Booths

Downflow booths are required by large-scale powder pack-off systems for material containment. They may also be applicable to liquid or solvent handling when none of the exhausted air is recirculated into the work area.

Air is supplied from the ceiling and drawn at the back end of the booth so as to ensure that the entire work zone is covered. Typical air velocity is 0.5m/sec. High velocity dust clouds are captured in the rear section of the booth therefore exhaust grill position must be taken into account in designing the pack-off system. In most applications the exhausted air is cleaned using both pre-filter and High Efficiency Particulate Arrestor (HEPA) then recirculated inside the booth. Air recirculation is especially beneficial if the air outside the booth is at risk of contamination (IChemE, 2002).

  • Requirements: pre-filter and HEPA filter, even when the booth is not in use, it is necessary to maintain air flow at a nominal level (i.e. 25%) of its full operational speed to prevent natural air from entering exhaust filters.
  • Applications: used for powder subdivision, process loading, tray dryer loading and unloading and large-scale powder pack-off system
  • Scale of operation: kilograms/ tons

• Laminar Flow Cabinets

The Laminar Flow Cabinet airflow is controlled, once-through, and non-turbulent. This ensures operators, products, and processes are protected from dust and fumes. A particle-free breathing zone is achieved for the operator by projecting air through a filtration system towards an exhaust chamber.

• Containment Isolators

The current technological advances in medicinal and biological research fields has allowed the introduction of highly-potent drugs in the market. In the past decade, 30% of active pharmaceutical ingredients (APIs) synthesized are potent drugs. Although they are advantageous in being effective at low concentrations, they pose hazards to industry personnel who are exposed to bulk amounts of the API during production. There is therefore a need for proper containment measures in different transfer processes including pack-off. In addition to personnel hazard, transfer operations may also lead to fires and explosions even in the absence of flammable gases or vapors. Explosion sensitive powders in particular have been known to cause fires in laboratories. In both cases, an isolation system is a requirement for material transfer operations.  

Pack-off booths with containment isolators offer product integrity and operator safety against highly potent or toxic chemical ingredients and explosion-sensitive powders. Isolators can provide both physical and aerodynamic barrier between the external environment and the work process. Handling and processing procedures done in isolated pack-off booths may be manual or automated (Glor, 2006).

  • Application: processing of highly-potent, hazardous or explosive substances, sterile applications
  • Containment Level: 1ug/m3 up to nanogram level
  • Air classification requirement: ISO 8 to 5

References:

Abdel-Magid, A.F. and Caron, S., 2006. Fundamentals of Early Clinical Drug Development: From Synthesis Design to Formulation. John Wiley and Sons Publication: USA. 163-168.

Glor, M., 2006. Transfer of powders into flammable solvents overview of explosion hazards and preventive measure. Journal of Loss Prevention in the Process Industries 19 (2006) 656–663

Institution of Chemical Engineers, 2002. Containment Systems: A Design Guide. Bell and Bain Ltd.: Glassgow, United Kingdom. 24-31.