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Maintenance Matters: Biological Safety Cabinets and Ductless Fume Hoods

For lab equipment as essential to protecting employees’ safety as biological safety cabinets (BSCs) and ductless fume hoods, making sure you’re looking after such equipment properly is crucial.

Rachel Muenz

Rachel Muenz, managing editor for G2 Intelligence, can be reached at

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Cleaning and chemicals are common errors when doing upkeep

The filter is the most important part of maintaining a ductless fume hood.“Preventive maintenance should not be taken lightly,” says John Peters, marketing director at NuAire (Plymouth, MN), about maintaining BSCs. “Standard Operating Procedures (SOPs) and training should be in place before any work begins inside the BSC.”

He adds that all maintenance, including certification and repair, must be done by a qualified technician familiar with the proper maintenance procedures required for the lab’s BSC. NuAire recommends that BSCs be certified at least once a year in accordance to the NSF/ANSI 49 Standard for Biosafety Cabinetry annex F.1.

For ductless fume hoods, the most important part of maintenance is the filter.

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“It is important that [users] recognize the filters are not just a simple replacement part,” says Erlab’s North American safety specialist Barbara Borzecki. “The filter is without a doubt the most crucial part of your … ductless fume hood and the guarantor of your health and safety.”

Erlab (Rowley, MA) hoods in particular, can have up to a 25-year lifespan if they are maintained correctly, she adds. Other ways to keep fume hoods in top shape include keeping track of the hood’s intended use and chemicals utilized, and to notify the manufacturer of any changes in use. “Erlab’s PhD chemists evaluate the chemical used, the filter’s retention capacity for each one, and how long the filter will last,” Borzecki says. “Replacing the filters as suggested by our lab is the key to safety.”

Helpful Resources to Consult

  • Onsite biosafety officer or environmental health officer
  • State or national organizations such as National Institutes of Health, Centers for
    Disease Control, Health Canada, etc.
  • Local service company
  • Certifiers
  • Vendor’s technicians/safety specialists
  • Training programs offered by the vendor or other experts

She adds that for Erlab hoods, which are manufactured in accordance with the AFNOR NFX 15-211 filtration safety standard, there is an alarm that notifies users when 60 hours of use has passed and they should look at their chemical evaluation to learn how long their filter will last. “If you are close to the replacement date, you should test the filter for saturation,” Borzecki says. “Some customers test for saturation once a month, others once a year. It depends on the usage. Others just replace the filter as recommended by Erlab.”

For BSCs, many cabinets also have alarm features that will trigger in the event of high or low airflow once the high or low set point has been reached, Peters says. “When a BSC cannot reach proper airflow, it usually means the HEPA filters need replacing.”

Under normal usage and barring a puncture, a BSC’s HEPA filters do not need replacement until the efflux velocity cannot be maintained or the access inflow velocity cannot be maintained at 100 LFPM (.51 m/s) (min.), Peters says.

Service Program Options:

  • Can be either direct from the manufacturer or a third-party service company
  • For Erlab ductless hoods in particular, enrollment in the Erlab Safety Program, (E.S.P.) is automatic when users purchase their hood, giving them eligibility for the company’s extended warranty program.
  • NuAire utilizes a network of third party and onsite facilities service personnel (i.e. university, pharmaceutical, etc.)

Other signs it’s time to do BSC maintenance are also fairly easy to spot, such as fluorescent lamp bulbs burning out or the blower motor failing to run.

“This [motor failure] can be recognized by viewing your airflow monitoring device and, more importantly, there will be no noise and no air being pulled into the BSC,” he says.

Users can easily replace light bulbs themselves, but Peters recommends they contact their service professional to replace the motor.

As far as common maintenance mistakes go, for BSCs, Peters says cleaning is a common one.

“Cleaning the cabinet is an important function in terms of both containment and sterility,” he says. “Disinfectants that use chlorides and halogens will cause damage to the stainless steel surface (if present) if left on for long periods of time.”

All BSC maintenance, including certification and repair, must be done by a qualified technician who is familiar with the unit.He recommends users set up and follow SOPs to avoid cleaning errors and that, if disinfectants use chlorides or halogens, users should “re-wipe all surfaces with 70 percent alcohol or similar non-corrosive anti-microbial agent to prevent damage to stainless steel surfaces.”

For ductless fume hoods, the most common maintenance errors are chemical-related.

“Many users assume that their filter is not saturated because they do not smell an odor,” Borzecki explains. “But many chemicals do not have an easily detectable odor.”

She adds many users don’t know the full list of chemicals used in their hoods.

“It is important to know the chemicals used and have a chemical analysis completed by the manufacturer and posted on the unit,” Borzecki says. “Any chemical not on the list should not be used in the hood without prior approval by the manufacturer. The chemical analysis determines the type of filter that will be used depending on the chemicals.”

Users can leave the unit running continuously to clean the air in the lab but this will shorten the life of the filter. And, as with any ductless fume hood, storage of chemicals is not recommended in the hood for safety reasons.