When it comes to your lab refrigerators and freezers, we made a case for why spending precious budget dollars on true medical-grade equipment can preserve your work. But, by contrast, we may sometimes have an inclination to buy more biological safety cabinet than we need—or, in this case, more features than we need.
When it comes to adding or replacing your cabinets, consider that less, in this case, may be more.
Want to learn more? Explore our on-demand webinar: Protect You and Your Science with Biological Safety Cabinets, at the Cell Culture Café.
Is external exhaust always necessary?
Biological safety cabinets are a necessary part of any cell culturing lab—and we see their ubiquity in TV shows and movies that depict our work. Deciding what kind of BSC to buy can be a complex choice that depends on the types of applications in your lab. So you’ll want to understand just how these cabinets work before you make that decision.
Class 2 Type B2 cabinets are externally exhausted, drawing air in from the lab environment and ventilating it through a canopy. This may seem like what we would all prefer. After all, who wants to risk allowing potentially contaminated air into our workspace? But that assumption doesn’t take into account the work done by the HEPA filter to remove contaminants from the air inside the cabinet, before it is circulated back out.
How the HEPA filter works
When you see a HEPA filter whose pore size is 0.3 microns—the kind used to filter bacteria—it seems logical that anything smaller than the pore size will pass through. But that doesn’t take into account the behavior of tiny particles, whose zigzag patterns in the filter’s membrane will cause them to become lodged as well. The HEPA filter is more of a forest than a single-layer net, and even viruses smaller than the pore size of the filter can get trapped as they pass through the membrane.
In fact, a HEPA filter has something called a “most penetrating particle size” (MPPS); anything smaller or larger will most likely be trapped and removed from the airflow. Know the MPPS of the filter you choose in the context of the materials you’re working with when selecting a new BSC.
So what’s the harm of buying more BSC than you need?
So why not just buy as much BSC as you can? Because you’ll expose yourself to a different kind of risk: spending more money than you have to. You may pay thousands more a year in air-conditioning and control costs for the externally exhausted cabinet. While a B2 cabinet is a necessary part of working with toxic gases, for example, the A2 is usually the best choice for cell culture work.
More on BSCs
To learn more about making the right choice for your lab watch our on-demand webinar, Protect You and Your Science with Biological Safety Cabinets, at the Cell Culture Café.
For help in selecting the right BSC, explore our Biological Safety Cabinet Education Selector.