Clean rooms use chemical fume hoods and biological safety cabinets to maintain safety standards for laboratory environments. These systems are often part of the overall HVAC system located within the clean room environment. Although known to be very effective, fume hoods and safety cabinets can be costly for installation and maintenance. A ductless laminar air flow hood provides an economical alternative to the hoods and cabinets designed with costly exhaust systems.
Not all environments are suited for the limitations of a ductless air flow hood system. However, a laminar air flow hood is suited for a variety of clean room environments. Ductless flow hood systems are not applicable for environments where lab experiment results are unknown, or if the known chemical results are exceedingly high.
Benefits of Ductless Air Flow Systems
The following below explain the benefits of a ductless laminar airflow unit.
Ductless hood units recycle room air while cleaning the contaminants. No air is removed from the laboratory! The saturated carbon filter may be disposed of safely at a landfill.
Laminar hoods are low maintenance air flow units. After hood installation, the only annual customer costs are filter replacements. Costs may range from $350 to $2,000 annually.
Laminar air flow units have no external connections beyond the power cord, allowing easy portability from room to room in a building. Portable flow hoods may be moved in minutes where an HVAC ducted hood system may be inoperable for weeks due to relocation procedures.
- Minimal Cost
Laminar hood systems are shipped at a location ready to use. Conventional hoods require blower installations, ductwork and fume hood assembly.
Laminar hood systems contain monitoring systems checking for gas and carbon filter saturation. The audible and visible alarms on the LCD monitor are set per ACGIH standards.
Laminar Air Flow Hood Models
- Vertical Workflow Stations
Vertical laminar work stations provide clean environments in two stages. First, the room air is cleaned with electrostatically charged bacterial pre-filter. The pre-filtered air is compressed and forged behind the HEPA filter and distributed over the entire work surface in a series of equal velocity parallel (laminar) lines.
Vertical workstations are suited for rooms not hazardous to the operator, but are still required to remain clean.
- Horizontal Work Flow Benches
Horizontal laminar workbenches are ideal for inspection parts, or the optic assemblies that require a clean working environment.
Work in a horizontal laminar flow hood should be performed at a distance of six inches minimum from the front edge of the working surface. Work performed at less than six inches, results in laminar air flow mixing with the outside air, resulting in contamination. Individual items may be placed no closer than three inches from the back of the hood. Workers should ensure that items do not touch the back of the filter.
Horizontal laminar benches provide protection from the processes, but not from the biological contaminants themselves!
- Free-Standing Clean Rooms
Free standing room enclosures are vertical laminar units designed to protect the
applications from room air contaminants. These units saturate experiments with
HEPA clean air, making them ideal for pipettors, equipment that requires a clean
environment, and clean room creation within warehouses for product sampling.
Free-standing clean rooms do not protect the operator from biological hazards.
Clean room environments are regulated. For example, pharmacy experiments are regulated by USP 797, the pharmaceutical chapter for sterile preparations. USP 797 regulates vertical and horizontal laminar hood stations to comply with ISO 5.
USP 797 laminar flow hoods for pharmacies should accommodate:
- Ophthalmic solutions
- IV admixtures
USP 797 contains a section regulating the location of controls for laminate hood and benches. The ISO 7 class locations are known as buffer areas. To ensure proper compliance, pharmacy retailers should consult with their laminar flow airflow hood provider to determine the appropriate size workstation for their clean room.