AS NZS 2243.9:2009 pdf free download – Safety in laboratories
4.1.1 General
A recirculating fume cabinet shall be designed to draw fumes released from operations in the cabinet away from the operator and through the filters. Containment is achieved by the appropriate airflow and minimization of turbulence. Turbulence can result from room airflow, cabinet design and apparatus in the work area. Containment of the fume shall be assessed by smoke testing carried out in accordance with Appendix A.
4.1.2 Face velocity
The face velocity shall be as uniform and stable as possible throughout the working aperture. When tested in accordance with Appendix B (with the access window or sash in the manufacturer’s stated working position), the average recirculating fume cabinet face velocity shall be not less than 0.5 m/s. Individual measurements shall be equal to or greater than 0.3 m/s. A minimum airflow of five recirculating fume cabinet volumes per minute shall be maintained at all times the cabinet is operating.
NOTES: 1 The face velocity may need to exceed 0.5 m/s to retain an exhaust rate of five fume cabinet volumes per minute.
2 Face velocities in excess of 1 m/s through the fully open sash can lead to local turbulence in front of the operator and generate overall instability of the airflow. High flow rates can lead to a lack of absorption in the filter.
3 An area where the individual measurement varies from the average by more than 20% should be investigated as this may indicate an area where containment problems could occur.
5.1.1 General
Recirculating fume cabinets shall be sited in areas that allow for safe and effective operation. Recirculating fume cabinets, including portable and trolley mounted cabinets, shall be sited in accordance with Clause 5.1.2 because airflow disturbances from traffic routes and other air handling devices can have adverse effects on fume containment. Environmental factors that can affect the efficiency of filtration and retention of absorbed fumes, such as temperature and relative humidity, should also be considered when siting a recirculating fume cabinet. The intended use of the cabinet, both tasks and frequency, should also be considered to ensure ongoing safe operation. The limitations of use outlined in Clause 2.2 shall be considered before using the cabinet.
6.2 GENERAL PROCEDURES
A recirculating fume cabinet shall only be used by competent persons who have been made aware of the limitations of the recirculating fume cabinet and who have been instructed in its use. The laboratory manager or supervisor shall identify the siting requirements of each recirculating fume cabinet, as outlined in Clause 5.1.2 and illustrated in Figure 2, and make all users aware of these siting requirements. A copy of the siting requirements should be attached to the recirculating fume cabinet. Recirculating fume cabinets shall only be used for absorbing the fumes that the fitted filter is designed for, and not for carrying out reactions that produce unknown products. Recirculating fume cabinets shall not be used as storage cabinets for toxic or flammable substances or in a flammable room atmosphere, unless the cabinet is specially designed for this purpose.