Biological Safety Cabinet Calibration Procedures

A biological safety cabinet, also called a laminar flow cabinet or tissue culture hood, is a closed stainless steel bench used to store particle-sensitive devices or biological samples. A HEPA filter draws air into the biological safety cabinet and across its contents to ensure that the air is flowing and free of particulates. Calibration of the biological safety cabinet should be performed only by qualified technicians so it conforms to factory and regulatory standards.

Recertification

• Establish normal air velocities according to factory standards by recertifying the biological safety cabinet after installation and on an annual basis. This involves field testing of the biological safety cabinet by a qualified technician. Recertify the biological safety cabinet after changing the HEPA filter, repairing or replacing internal parts and moving the cabinet to a different location.

Set the Digital Manometer to Zero

• Access the "Sentry/Reset" slide switch through the work access opening and set it to "Reset." Remove the hoses from the pressure transducer on the printed wiring board and set the digital manometer display to zero. There should be no signal to the pressure transducer. The pressure transducer is a sensor that measures the air pressure within the biological safety cabinet, while the manometer displays the measurement. Reconnect the hoses into the pressure transducer.

Air Barrier Velocity

• Mount a thermo-anemometer at the work access opening to measure air barrier velocity, since this point is indicative of the average velocity. The thermo-anemometer is a device used to measure air speed, while air barrier velocity is the velocity of the air as it passes the barrier at the work access opening. The average air barrier inflow and the total cabinet exhaust flow measurements in CFM (cubic feet per minute) are already determined and equal to each other. Adjust the setpoint as determined by the manufacturer to the necessary air barrier velocity.

Low-Limit Setpoint

• The calibration system is located parallel to the electrical system, and it automatically adjusts the manufacturer-determined setpoint while the biological safety cabinet is in use. Establish a low-limit setpoint by turning the shaft on the calibration system counterclockwise to decrease the speed of the blower. The digital display indicates the low-limit setpoint. Press the "Set Low Limit" button and turn the "Low Limit Adjust" control to the value of the low-limit setpoint. Turn the shaft on the calibration system back to its initial position.

Complete the Process

• Return the biological safety cabinet to operating condition by moving the "Sentry/Reset" slide switch back to "Sentry."