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Detection of inflow airflow velocity in biosafety cabinets

Detection of inflow airflow velocity: The biological safety cabinet is tested according to YY 0569-2011 6.3.8, a non-stick tape is attached to the lower edge of the front window from left to right, a measuring point is set at the centre line of the width of the front window opening, and a measuring point is set at every 100 mm interval to both sides. If the width of the front window opening is 1240 mm, for example, the centre line is 620 mm, the centre line and from the centre line to both sides of each interval of 100 mm set measurement points, the centre line to both sides of the fifth point and both sides of the wall distance of 120 mm to meet the requirements, the entire width of the front window opening set a total of 11 measurement points. The positions of the measuring points are marked on non-stick tape.
To limit the height of the front window opening (both open the maximum safety height of 3/8 position), open the front window until the biosafety cabinet alarm sounds and then return to the alarm disappears, measure the height of its dimensions and multiply by 3 divided by 8 to measure the inflow airflow rate required to open the front window limit height, this height is both the front window opening to the maximum safety height of 3/8 position, [such as the front window opening maximum safety If the maximum safe height of the front window opening is 10 inches (254 mm), the height at the 3/8 position should be 95.25 mm], pull the upper edge of the front window opening back to this height position.
Orient the red wind direction point on the anemometer probe in the direction of the incoming airflow and clamp the probe measuring rod perpendicular to the work surface on the burette stand, adjust the red wind direction point on the anemometer probe to the centre line of the front window opening to a maximum safe height of 10" (254 mm) at 3/8 (47.62 mm above the work surface) and press it against the outside of the front window glass and move the burette stand so that the red wind direction point on the anemometer probe is at a maximum safe height of 10" (254 mm). Move the burette holder so that the red wind direction point on the anemometer probe is aligned with the position of the measuring point set by the non-adhesive tape.
Turn on the anemometer according to the above operation and measure each measuring point in the order of its number. Press "HOLD" again to exit data hold and proceed to the next point, record the measured values for all points and calculate the average value from the measured values.
Calculate the average velocity of the airflow into the front window.
υ = υ. x 0.375 + 0.05 m/s                                
   Note: υ - the average velocity of the airflow into the front window, m/s.
       υ. - average airflow velocity at the measurement point, m/s.
0.375 - factor limiting the opening height of the front window operating opening to the maximum safe height of opening (3/8).
   0.05 - correction value for airflow velocity, in m/s.
According to YY 0569-2011 5.4.8 standard "The average inflow airflow velocity of Class II safety cabinets shall be between the nominal inflow airflow value ± 0.015 m/s; the average inflow airflow velocity of Class II A2 safety cabinets shall be not less than 0.5 m/s, and the flow rate per metre width of the working area shall be not less than 0.1 m3/s". The measurement results are evaluated and a conclusion is given as to whether they pass or not.

In the previous:Performance and test method of biochemical incubator The next article:Biological Safety Cabinets - Falling Air Flow Rate Detection Method
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