Laminar flow cabinet

A safety cabinet for genetic or microbiological work or work with cell cultures is a work table in a housing that is so belüftetet that the escape of microorganisms and aerosols is complicated by the air stream. In addition to the protection that can also serve to protect the work object from contamination a safety cabinet to their workers. Safety cabinets are also called laminar flow or sterile chamber. In English, between the simple laminar flow cabinet (also called flow) and the Biological Safety Cabinet or Microbiological Safety Cabinet distinguished (see safety classes ).

Protection classes

There are safety cabinets in different security levels:

• Class I - Protection of workers
• Class II - Protection of workers and the working object
• Class III - increased protection of workers, protection of the work object

Function

To prevent airborne organisms, spores or aerosols ausdringen, air is drawn from inside the safety cabinet through a HEPA filter. A portion of the extracted air is blown along the ( to work open ) front back into the work area. To this end, above the working area a powerful ventilation system is installed.

In safety cabinets Class I in room air is drawn into the work area.

In safety cabinets Class II (Biological Safety Cabinet) a portion of the filtered exhaust air is blown in laminar flow as the " air curtain " along the partially open front window down and re- fed together with the intake air to the filter, so that the incoming fresh air is cleaned, before it comes into contact with the work material. At the same time with this, the risk is minimized, that particles can get into the lab environment from within the workbench ( safety chamber ) through the partially opened front window. Sensors trigger an alarm when the laminar flow is so greatly disturbed that indoor and outdoor air are mixed by vortex. This can happen when the front plate is opened too far. Another possible cause is the storage of too many objects within the safety cabinet. These items may adversely affect the airflow. Class II cabinets are available with two or three filters (mostly HEPA) equipped. Three filter systems which are used primarily for the preparation of cytostatics. A safety cabinet class II A uses about 30 % of the filtered exhaust air to re venting of the containment chamber. Class II B devices carry the air from 100% (filtered). For this, these devices must be connected to a building internal exhaust system. This is mandatory in various European countries.

Safety Cabinet Class III (English: glove box ) are fully closed. They feature built- gloves and locks, are introduced by the tools and working materials. Both supply air and exhaust air can be passed through HEPA filters, a negative pressure is maintained in the interior, so that no potentially contaminated from leaking inside air in case of leaks. These safety cabinets are listed in the EU dual-use equipment and are potentially subject to export restrictions.

Regulations

Safety cabinets are used to protect the working person (as well as the work object ). There are various standards to be followed by a safety cabinet. This includes the EN 12469 in Europe and in the USA the NSF49. A certification by an independent testing laboratory is recommended. After the construction of the safety cabinet in the laboratory, an acceptance test by a certified body is recommended. The WHO recommends a maximum shelf life of 15 years.

Other Equipment

The interior of safety cabinets is modularly designed stainless steel or other suitable materials, that the work surface can be taken out to them and to clean the space below. There will often be inside the safety cabinet suction devices for liquids, electrical outlets and gas connections. Safety cabinets can be equipped with UV lamps to sterilize the interior. These must be turned off when working in it, as they can quickly lead to skin damage (sunburn). They, too, would the cells that are being worked with harm, or kill. The front side of safety cabinets is equipped with a pane of glass that can be completely closed. This windscreen is moved manually with older devices, with modern equipment, this is done electrically by a motor. The front window is shut down when not in it, especially when it is sterilized with ultraviolet light.

Ergonomics

Safety Cabinets are of laboratory staff mostly daily and tw. used several hours. In addition to protecting the working person and the sample material, the aspect of ergonomic working is increasingly important. These include the least possible noise through the air conditioning, a height-adjustable work surface and strong but glare-free light sources.

Maintenance

Safety cabinets must be serviced regularly. This checks whether the airflow meets the requirements, so the safety of working person and, if necessary, the sample material. The filters have a limited service life. Depending upon the purity of laboratory air and the purity of the samples, the transmittance of the filter is reduced with time. Modern safety cabinets measure the filter air flow. Is this too low, an alarm sounds. The filters should be replaced only by qualified personnel, since the filters are potentially to be regarded as infectious material. When using a UV lamp should this be exchanged depending on the daily use of time after a certain time interval. The radiation power of the UV lamp can with time, so that a complete sterilization of the working surface may is no longer guaranteed.

Built in the Laboratory

Unlike other laboratory equipment ( pipettes, centrifuge, thermocycler ) safety cabinets are very large (about 2.40 m high, 80 cm deep, up to 2 m long), and heavy ( up to 350 kg). An exact measurement of the laboratory, if necessary, checking the load of blankets and elevators and hallways and doors between the building entrance and the planned location of the safety cabinet are essential. The positioning of the safety cabinet within a laboratory room is a function of the position of the doors as well as of the ventilation system. The workplace of a safety cabinet should have as little external air turbulence.

Demarcation

Safety cabinets are sometimes confused with deductions. However, safety cabinets provide as opposed to deductions only protection against particulates and aerosols, gases and vapors are not retained in their filters.

Cleanroom workbenches are not as safety cabinets, especially the protection of workers in mind, but the protection of the product or work item.

Safety cabinets can also be used for non- biotech work under clean-room conditions, such as in semiconductor manufacturing.

A glove box is designed to work in perfect agreement as possible on the material to be treated, usually with a special atmosphere.