Changing Biosafety Cabinet HEPA Filters
Be sure to familiarize yourself with your operation and maintenance manual.
HEPA filters, whether part of a building exhaust system or component of a biosafety cabinet (BSC), will require replacement when the airflow is no longer sufficient, and filter load has reached capacity. Filters must be decontaminated before removal. To contain the formaldehyde gas typically used for microbiological decontamination, exhaust systems containing HEPA filters require airtight dampers to be installed on both the inlet and discharge side of the filter housing. This ensures containment of the gas inside the filter housing during decontamination.
Access panel ports in the filter housing also allow for performance testing of the HEPA filter.
HEPA filters are typically constructed of paper-thin sheets of borosilicate medium, pleated to increase surface area, and affixed to a frame. Filters may be built as separatorless or contain aluminum sepearators for stability.
A bag-in/bag-out filter assembly can be used in situations where HEPA filtration is necessary for operations involving biohazardous materials and hazardous or toxic chemicals. This protects the technician handling the filter as well as the environment.
The bag-in/bag-out system is used when it is not possible to decontaminate the HEPA filters with formaldehyde gas, or when hazardous toxic chemicals have been used in the BSC.
Note: The bag-in-bag-out requirement must be identified at the time of purchase and installation; a BIBO assembly (available only on B1 & B2 Cabinets) cannot be added to a cabinet after the fact.
Certification and Annual Ultraviolet (UV) Light Check
A BSC must be certified by a qualified individual at the following times:
- Initial Installation It is critical that all new Biological Safety Cabinets be certified when they are received from the manufacturer. Failure to do so may lead to the use of a cabinet which is not functioning appropriately and cause the owner to pay for repairs which should be covered under the purchasing agreement.
- Moved or Relocated Relocating a BSC may break the HEPA filter seals or otherwise damage the filters or the cabinet.
- After a Major Repair, such as replacement of HEPA filters or motor.
- Annually - Each BSC should be tested and certified at least annually to it is operating correctly.
On-site testing following the recommendations for field testing [NSF/ANSI 49-2011 (Annex F) or most current version] must be performed by experienced, qualified personnel. Some necessary information is included here to assist in understanding the frequency and kinds of tests to be completed.
Use Accredited Field Certifiers
It is strongly recommended that accredited field certifiers be used to test and certify Biological Safety Cabinets whenever possible. If in-house personnel is performing the certifications, then these individuals should become accredited. The importance of proper certification cannot be emphasized enough since persons who manipulate infectious microorganisms are at increased risk of acquiring an occupational illness when their Biological Safety Cabinets are functioning improperly.
The annual tests applicable to each of the three classes of Biological Safety Cabinets are listed and described below. There is also information regarding the conduct of selected tests. Biological Safety Cabinets perform consistently well when proper annual certification procedures are followed; cabinet or filter failures tend to occur infrequently.
Performance Testing Biological Safety Cabinets in the Field
Biological Safety Cabinets are the primary containment device that protects the worker, product, and environment from exposure to microbiological agents. Performance of Biosafety Cabinetry is viable to ensure maximum protection and minimize contamination. Performance specifications have been established by NSF/ANSI Standard 49 for the evaluation of Class II laminar flow biological safety cabinets. Various tests have been developed within these standards to confirm your biological safety cabinet is operating at a standard level.
Tests such as downflow and inflow velocity, airflow smoke patterns, filter leak, light intensity, vibration, noise level, and UV light integrity will be performed by an accredited field certifier at least on an annual basis to certify the integrity of your biosafety cabinet system is running at peak performance levels.