Biosafety cabinet-2

Class III

Class III cabinets are typically only installed in maximum containment laboratories and are designed to work with BSL-4 pathogens to provide maximum protection.The enclosure is airtight and all materials enter and exit through filling tanks or double door autoclaves. Gloves attached to the front protect against direct contact with hazardous substances (Class III cabinets are sometimes called glove boxes).These custom cabinets are often joined in a line, and the laboratory equipment installed inside is also usually custom.

Ergonomics

Biological safety cabinets are used for several hours a day.In addition to protecting the user and the sample material, the human design factor (ergonomics) of the work is becoming more and more important.These include reduced noise levels (for a more convenient working environment), height-adjustable stands or stools and footrests (for optimal sitting posture), panoramic side windows (for more light in the cabinet), front sash angled at 10° ( better sitting position), strong light sources (better visibility into the cabinet),forearm supports for increased comfort and safety, and extended access and angled viewing windows for improved working conditions.

Ultraviolet lamps 

CDC does not recommend installing UV lamps in biological safety cabinets.‰12–13‰ Clean and replace the bulb.UV lamps should not be used as the primary source of decontamination of BSC interior surfaces.However, these assertions have been formally challenged in at least one peer-reviewed article, which states:

• No citations to state the need to remove dust and grime from bulbs

• A properly functioning BSC has very clean air, so dust is less likely to accumulate

• Laboratories are often air conditioned, eliminating concerns about the effectiveness of humidity in inhibiting UV rays

• When used properly, the risk of user exposure to UV light is very low

• UV disinfection is effective in killing bacteria and viruses and inhibits DNA contamination of PCR

• The advantage of UV disinfection is that it does not leave residues like physical disinfectants

• The relative safety and risks of UV light versus other disinfection techniques (which also have risks) should be considered.

Maintenance and service

Biological safety cabinets are generally required to meet the standards of that country or region.This requirement may be administered by agencies such as the TGA, FDA or WHO.For example, in Australia, Class II BSCs are required to meet a building standard called AS2252.2.These standards reference several other standards such as AS2243.3.AS2243.3 classifies the level of risk posed by microorganisms according to their pathogenicity, mode of transmission and host range, as well as current preventive measures and effective treatments.Class II BSCs have specific field testing requirements.The US base for field testing is NSF49; Europe relies on EN12469; Australia has the AS1807 series of test methods (referenced in AS2252.2) Field testing requirements may include:

• Air velocity in the work area.

• Air barrier test (barrier between operator and product; some standards use inward velocity test instead)

• Filter integrity (leak test or amount of aerosol the filter allows to pass)

• Particle counts in the workspace

• Air tightness

• Work Area Leak Test (Work Area Integrity Test)

• Illumination in the work area

• UV effects

• Sound level.

In general, a scheduled service maintenance plan may include the following tasks:

Verify airflow and filter capacity.Filters have a limited lifetime depending on the air quality in the laboratory space, the amount of particles and aerosols generated in the BSC workspace, and the amount of air passing through the filter.As these filters get loaded, the internal fan has to do more work to push/pull the same volume of air through them.Newer cabinets constantly measure airflow and self-compensate for fan performance to ensure a constant amount of air passing through the filter and cabinet.However, self-adjusting cabinets should be cross-validated with calibrated instruments to ensure performance remains at the correct level.Audio and visual alarms will alert the operator if flow is below expected performance.Filter replacement should be restricted to trained personnel as filters may become contaminated.This can be done after the cabinet has been decontaminated using a gas procedure (using formaldehyde, chlorine dioxide or vaporized hydrogen peroxide) or a "bag in/bag out"procedure.Check and replace UV lamps. The power of UV lamps decreases over time,resulting in less effective disinfection of the work area.