Biological safety cabinet performance

Stuart, D.G., R.L. Jones, D. Eagleson, and J.M. Eagleson, Jr. 1984. Practical application of biological safety cabinet performance envelopes. Read before the XXVII Biological Safety Conference, Raleigh, NC. 

Temperature and humidity is controlled to minimize evaporation of reagents and to keep performance of electronic equipment optimal. Ventilation is adequate for the removal of noxious fumes and odors. Formaldehyde and xylene vapor concentrations must be below maximum permissible levels. For formaldehyde, this level is 0.75 ppm for an 8-h time-weighted average, or 2.0 ppm for a 15-min short-term exposure. For xylene, the level is 100 ppm for an 8-h time-weighted average and 200 ppm for a 15-min short-term exposure. The monitoring of the work area and employees can be performed on a yearly basis. Chemical and biological safety cabinets are checked for proper airflow on a yearly basis. 

Unless imaging, all cell work is performed under a biological safety cabinet. 

During the preparation of hazardous drugs, use a ventilated cabinet to reduce the potential for occupational exposure. Performance test methods and criteria for BSCs may be found in Primary Containment for Biohazards Selection, Installation and Use of Biological Safety Cabinets, second edition, CDC/NIH, 2000. A current field certification label should be prominently displayed on the ventilated cabinet per NSF/ANSI49. 

When used with biohazardous materials, centrifuge tubes, rotors, and accessories should be filled and opened in a biological safety cabinet (215). If centrifuging of biohazardous substances is to be performed outside a special containment cabinet, a sealed safety bucket or tube should be used (Figure 1.6). After the safety bucket or tube is filled and sealed, it should be considered potentially contaminated and should be wiped with a cloth soaked in disinfectant. Since some disinfectants are corrosive to centrifuge rotors and buckets, rinsing the rotor or bucket with clean water is desirable after an appropriate contact time in disinfectant has elapsed. 

It has not been easy to determine the factors required to assure maximum performance efficiency of the Class II biological safety cabinet. In its Standard 49 (326) the National Sanitation Foundation (NSF, an industrial organization that sets standards for the performance of cabinets) has attempted to define efficiency and performance for these cabinets. Unfortunately, many factors influence efficiency and performance after the cabinet is removed from the ideal situations that prevail in the factory or in the NSF testing laboratory. All Class II cabinets are manufactured to meet the standards set by NSF 49. At a minimum the average airflow velocity cannot deviate by more than 5 linear feet per minute (Ifpm) from the established set point for a particular cabinet model. However, in practice, the airflow velocities may vary significantly more than this. These variations result from some of the following factors that are external to the design and operation of the cabinet ... 

Figure 9.8 Determining the performance envelope. A variation in line voltage can have a marked effect on the performance of a biological safety cabinet. The performance envelope allows the cabinet designer to predict the effects of changes of operating conditions on overall cabinet performance. (From [25, 368] and used by permission of the Baker Company.)...

There are certain guidelines which must be followed to ensure the proper use of the Class II biological safety cabinet. Before using the cabinet, the operator should ascertain whether it has been inspected for proper operation by a qualified technician, and whether it has passed certain tests to ensure that the performance of the unit meets the minimum standards set in the NSF Standard 49 (326). This series of tests, known as a certification, minimally consists of testing the integrity of the... 

Rake, B.W., R.A. Hales, and F.J. Harms. 1983. Definition of the performance envelope of a Class II Type A biological safety cabinet. Proc. of the XXVI Biological Safety Conference, pp. 36-46. Houston, TX. 

All procedures are performed carefully to minimize the creation of splashes or aerosols. Biological (microbiological) safety cabinets are used for procedures that may generate aerosols. 

In the future this innovation in the testing of the performance of biological safety cabinetry will make it easier to evaluate cabinet performance when the cabinets are serviced and certified. The use of the cabinet performance envelope concept can teach us much about the effects of fan performance, filter loading, and cabinet placement on cabinet performance. 

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