If your biological safety cabinet is nearing 15 years of service, it is probably time to replace it. The likelihood of service and repair needs, compounded by the dwindling availability of appropriate parts and the improvements in ergonomics, cabinet performance and energy efficiency, all conspire to tilt the decision-making process heavily in the direction of “replace.”
Biological safety cabinets (BSCs) protect both personnel and the lab environment from exposure to hazardous substances and reduce the risk of cross-contamination. The design and engineering features incorporated in new units enable them to do this better and more cost-effectively than older units. NSF/ANSI Standard 49, which specifies design, construction and performance criteria for these cabinets, also hews to the 15-year replacement standard.
The service requirements on older hoods should be given serious consideration. Blowers, motors and electrical components require more maintenance, if not replacement, as units age. Replacement parts can be difficult to obtain for units approaching the 15-year cut-off; even the fluorescence lights specific to some cabinets are no longer available.
Unit performance has also undergone a revolution in recent years. Improvements in product design, airflow optimization and testing methods have significantly increased the containment ability and performance of cabinets. After 1992, manufacturers were required to adjust and/or improve cabinets to meet the conditions of the revised standard. Tests included direct measurement of inflow velocity, motor/blower performance and biological safety containment performance tolerance testing. The direct inflow measurement test provides an accurate and consistent method and thus makes sure proper airflows are being set during the certification process; the motor/blower test ensures a minimum HEPA filter loading capacity. While the previous NSF standard only required biological testing at the nominal airflow setpoint, the revised standard specifies this at multiple airflow setpoints, which tests the BSC for abnormal airflow conditions, all with the goal of providing a more robust containment system. Since the revised standard took effect in 1992, any BSC submitted after 1992 would be subjected to these new tests.
Furthermore, modern hoods offer significant improvements in energy efficiency, consuming as little as one-fifth that of units approaching the 15-year mark. Reduced energy costs thus have to be included in a repair/replace discussion.
All in all, the case for upgrading equipment that is beyond 10 years old, and certainly approaching 15 years, is strong. Increased maintenance and repair costs and reduced energy consumption will pay a lot towards replacement costs. When unit performance—better sample, personnel and laboratory protection; ease of use; compliance with institutional sustainability programs—is factored in, the argument for replacement is strong.