The Differences Between Biosafety Cabinet Class I and Class II

When it comes to purchasing biosafety cabinets for laboratories, you need to undertake the appropriate level of research and make sure that you purchase a product that's fit for purpose. The safety of your laboratory and lab staff could very well depend on it.

There are three different classes of biosafety cabinet, but even these are broken down into further sub-categories. It pays to know what work certain cabinet classes are designed for, and what they're not designed for.

In this article, we will focus only on Class I and Class II Biosafety cabinets.

What are biosafety cabinets?

Often referred to as biological, biohazard, microbiological, or safety cabinets (the list is endless), they are ventilated enclosures that protect users from any potentially harmful specimen and, in some cases, the sample from being contaminated by unclean air.

The purpose-built cabinets include a fully enclosed workspace that allows users to carry out experimental tasks without exposing themselves or their surrounding environment to biological hazards.

These units are typically found in clinical, research, biotech and pharma labs worldwide.

Ok, so what are biosafety cabinet classes?

We've made them sound like one coverall piece of laboratory equipment.

However, the truth is that there are several different types of units, a range of categories, and various levels of protection on offer from each of them.

There are three different types of cabinet class, as explained below.

Class I

This is the most basic, fundamental class of safety cabinets. It's defined as "a ventilated unit for personnel and environmental protection".

With Class I cabinets, the protection is for the user only. Airflow is not recirculated, flows away from the operator under negative airflow pressure, and has a HEPA filter at the exhaust outlet. Testing that will be carried out on a Class I cabinet will include airflow containment testing, Ki-Discuss testing and DOP testing. 

Class II A2 (Recirculating)

Class II biosafety cabinets take that level of protection up a notch, and in some cases, the design can become quite complex. 

In the simplest terms, this class of cabinet offers the same as Class I, but in addition to protecting the user from hazards, it also protects the sample in the cabinet from the surrounding environment. 

In a similar design to Class I, there is still an inward airflow through the open front sash. A HEPA filter still cleans the exhausted air, but a key difference is that an additional HEPA filter filters 70% of the air and directs it vertically down onto the work surface in a Laminar Flow. This laminar flow clean air stream ensures the sample being worked on maintains its sterility and prevents cross-contamination. 

There are minimum average airflow velocity requirements (depending on the type) and a range of exhaust arrangements that can recirculate clean air within the exhaust and the working chamber.

This class of cabinet in A2 format are a primary focus of TION, as these are by far the most popular specifications in the industry.

Class II B2 (Ducted)

A Class II B2 Biosafety cabinet works exactly the same as a Class II A1 cabinet, with one difference. Instead of recirculating the air in the chamber, 100% of the contained air is exhausted to the atmosphere through a HEPA filter. To maintain a vertical stream of laminar flow clean air onto the workbench, an auxiliary fan is installed in the cabinet that draws air through a HEPA filter and onto the work surface. This air is then extracted through the exhaust HEPA and to the atmosphere. 

Class III

This version is completely enclosed, ventilated, and leak-tight. For obvious reasons, they are often known as 'glove boxes'. This is an article for another day! 

Biosafety cabinets with TION

TION's biosafety units have been designed for optimum operator protection and laboratory safety. Our stainless steel worksurfaces make maintenance straightforward and portable cabinets are height-adjustable too. A corrosion-proof carcass, programmable sterilisation lights, and the user-friendly interface make our cabinets the safest in the industry.

There's a reason why many of the leading pharmaceutical and technological brands trust our fume extraction systems. Get in touch to find out how we can help equip your lab with the safest biohazard cabinets available in the UK.

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