Bioveiligheidskasten

A bioveiligheidskast klasse I is a laboratory workstation that is used to protect the user against biohazards. The cabinet has a unidirectional upwards airflow and sucks the air trough a HEPA filter before re-sending it into the laboratory environment. Due to the flow direction, unfiltered air is passing by the product/experiment used inside the cabinet. In practice, for most applications involving biohazards, the cross contamination with unfiltered air is a problem. That is why the bioveiligheidskast klasse I has almost disappeared from the lab environment. Besides the problem of cross contamination, the cost of the cabinet is more or less the same as the cost of a bioveiligheidskast klasse II type A2, which does offer protection of the product/experiment against air contaminants.

A bioveiligheidskast klasse II is a laboratory workstation providing user and environment protection against biohazards AND providing protection of the product/experiment against air contaminants. The European standard allows the users to choose which type of class II cabinet they use, as long as it complies with certain test criteria. In practice, a bioveiligheidskast klasse II type A2 is used for around 95% of applications involving biohazards within Europe.

When low concentrations of chemicals are used in a class II A2 biosafety cabinet, it is in most cases connected to the laboratory HVAC system using thimble ducting. The flow rate just needs to be above a certain minimum and does not need to be regulated exactly. An alternative is adding a carbon filter on top of the exhaust filter, but this technology is not used a lot yet in biosafety cabinets. The only limitation of a bioveiligheidskast klasse II type A2 is when you use large quantities of volatile chemicals in the same workstation as biohazards. Because a class II A2 re-circulates 70% of the air, there is the possibility that chemical vapours build up. When these are toxic or explosive, they can be a large safety risk. In this case the other types of the American standard are better solutions. Biosafety cabinets class 2 type B1, B2 and C1 are all biosafety cabinets that are developed to work with large quantities of volatile chemicals in the same cabinet where biohazards are used. They are connected to an HVAC system. The flow rate needs to be regulated very exactly for these 3 types of cabinets using hard ducting. In practice this means an individual HVAC system with an individual FAN unit needs to be installed in the laboratory dedicated for these cabinets. This makes the installation a lot more expensive and complex compared to a type II A2. The scope for a bioveiligheidskast klasse II type B1, B2 and C1 is exactly the same. In practice laboratories will never choose type B1 and C1 because they have the same cost as a B2, but use of chemicals is limited to certain parts of the work area.

                                      
A bioveiligheidskast klasse III is a laboratory workstation that protects the user and environment against biohazards and the product/experiment against air contaminants. The main difference with a bioveiligheidskast klasse II is that there is a complete physical separation between the user and the product/experiment, while a class II has a sash opening. It is also sometimes referred to as an isolator, but this name is used also for some other cabinet types. Materials need to be entered via an air sash, and the manipulations are done using long gloves that are integrated into the front window. This type of cabinet is usually only found in biosafety level 4 laboratories.

If you use small amounts of chemicals, you can use a bioveiligheidskast klasse II A2. You just need to connect it to the HVAC system using an exhaust collar and ducting. The flow rate needs to be above a threshold communicated by the supplier of the cabinet. An alternative for ducting is using a carbon filter. Carbon filters have coatings that can capture chemicals using a process called adsorption. When using large volumes of volatile chemicals in the same workstation as biohazards, you need to keep in mind that a bioveiligheidskast klasse II A2 has 70% re-circulation. This can cause build-up of chemical vapours inside the workstation and create a risk. If a bioveiligheidskast klasse II A2 is not an option for that reason, the bioveiligheidskast klasse II B2 is the best solution.

Het is voor eindgebruikers erg verwarrend om het juiste type microbiologische veiligheidskast te vinden. Dit heeft te maken met het bestaan van twee verschillende normen:

• Allereerst is er de oudere Amerikaanse norm NSF 49. Deze norm gaat enkel over klasse II microbiologische veiligheidskasten en definieert vier types op basis van hun constructie.
• Daarnaast is er de nieuwere Europese norm EN 12469. Deze norm definieert drie klassen van microbiologische veiligheidskasten, maar legt niet vast hoe deze gebouwd moeten worden. Ze moeten enkel voldoen aan bepaalde testcriteria.

In Europa moeten we uiteraard de Europese norm volgen. In de praktijk zal voor de meeste toepassingen een klasse II microbiologische veiligheidskast nodig zijn. Aangezien de Europese norm weinig zegt over de constructie, kunt u kiezen uit alle types die door de Amerikaanse norm gedefinieerd zijn. In de praktijk zien we dat ongeveer 95% van de microbiologische veiligheidskasten in de Benelux van het type klasse II A2 is. Hoe komt dat?

Analis biedt als exclusief verdeler van Esco voor de BeNeLux ook de nodige ondersteuning. We beschikken over een lokaal serviceteam voor installatievalidatie, preventief en correctief onderhoud.