Biological safety cabinets are one of the primary safety measures in any laboratory setting that deal with microbes and infections agents. These secure, ventilated enclosures ensure that when handling potentially dangerous contaminants, laboratory workers are kept safe and isolated from fumes and the spread of hazardous particles.
To maintain the necessary levels of protection, biological safety cabinets must be regularly tested and certified, and they are subject to the NSF/ANSI 49 Standard. How often should biological safety cabinets be certified? Under normal circumstances, at least every 12 months. This should account for the baseline amount of “wear and tear” and handling that occurs over a year of cabinet usage. For certain scenarios, semiannual (twice-yearly) testing is required.
There are several other circumstances, however, under which cabinets should also be tested. When should biological safety cabinets be certified in the interim? Generally, they should be tested after any event that has the potential to affect the condition or performance of the equipment: major maintenance, accidents, replacement of HEPA filters, equipment or facility relocation, and after periods of extended shutdown, for instance.
A fine mist of potassium iodide droplets, produced by a spinning disk, is used as a challenge aerosol to measure the containment of a biosafety cabinet.The collectors deposit any potassium iodide particles that are in the sampled air on the filter membranes. At the end of the sampling period the filter membranes are placed into a solution of palladium chloride whereupon the potassium iodide “develops” to form clearly visible and easily identified grey/brown dots.
According to EN 12469:2000 Apf (cabinet protection factor) has to be less than 100,000 for each collector or there should not be more than 62 brown dots on the KI discus filter membrane after development in palladium chloride.
Biological safety cabinet testing and certification involves several tests, some required and some optional, depending on the purposes of the testing and the standards that must be met.
Required certification tests typically comprise:
1,Inflow velocity measurements: Measures the intake airflow at the face of the unit to ensure biohazardous materials do not escape the cabinet where they would pose a risk to the operator or the laboratory and facility environment.
2,Downflow velocity measurements: Ensures that airflow inside the work area of the cabinet is operating as intended and is not cross contaminating the work area within the cabinet.
3,HEPA filter integrity testing: Checks the HEPA filter integrity by detecting any leaks, defects, or bypass leakage.
4,Smoke pattern testing: Uses a visible medium to observe and verify proper airflow direction and containment.
5,Site installation testing: Ensures units are properly installed within the facility in accordance with NSF and OSHA standards.
6,Alarm calibration: Confirms that airflow alarms are properly set to indicate any unsafe conditions.
1,Non-viable particle counting - for the purpose of ISO classification of a space, normally when patient safety is a concern
2,UV light testing - to provide a µW/cm² output of the light to calculate proper exposure time based on existing contaminants. An OSHA requirement when UV light is used for decontamination.
3,Electrical safety testing - to address possible electrical safety issues on units that are not UL listed
4,Fluorescent light testing, Vibration testing, or Sound testing - worker comfort and safety tests that can demonstrate if further safety protocols or repairs could be required.