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Biological Safety Cabinets - Falling Air Flow Rate Detection Method

Empty the biosafety cabinet before testing and check the location of the power switch on the biosafety cabinet and the location of the sockets in the laboratory where electricity can be taken. Check and record the model and production batch number of the biosafety cabinet and record its specification.
Apply a strip of non-stick tape parallel to each other on the worktop of the cabinet at a distance of 140 mm from the inner front wall and the front of the operating area, and at the centre line of the inner front wall and the operating opening of the front window.
Appearance inspection: according to YY 0569-2011 6.1 check whether the surface of the cabinet has obvious scratches, rust spots and indentations, whether the surface is smooth and whether the shape is flat and regular; whether the text and graphic symbols describing the function are correct, clear, correct and firm; whether the welding is firm and whether the welding surface is smooth.
The airflow velocity detection: according to YY 0569-2011 6.3.7, on the centre line of the three parallel non-adhesive paper strips that have been attached to the work surface of the biological safety cabinet, a measuring point is laid at a distance of 150 mm from each of the left and right side walls, and then within the spacing between the left and right two points of the three parallel non-adhesive paper strips, a measuring point of not more than 150 mm is set at equal distance (e.g. the distance between the left and right side walls of a safety cabinet is 1240 mm, minus the distance between the left and right side walls). 1240 mm, minus the distance between the left and right two points 300 mm after the remaining 940 mm, between the equal spacing set no more than 150 mm measurement points, need to be divided into 7 equal parts that is, lay 6 points each point spacing of 134.28 mm, each row set 8 measurement points, set three rows of a total of 24 measurement points), the numbering sequence of measurement points from the front wall from left to right, the middle row from right to left, the front row from left to right in the order of 1 The points are marked on the non-stick tape in the order of 1, 2 and 3 natural numbers. Clamp the anemometer probe to the burette holder and pull the probe out of the measuring rod with the red windward point on the probe facing upwards in the direction of the incoming wind (note: do not squeeze the metal mesh of the probe with your hands as this may cause deformation and lead to a reduction in the accuracy of the wind speed measurement). Adjust the height of the anemometer probe to a level of 100 mm above the working area and above the top edge of the front window opening [if the top edge of the front window opening is 10" (254 mm), add 100 mm to the measurement height to a level of 354 mm above the work surface of the cabinet and align the position of the red wind direction point on the anemometer probe with one of the corners of the burette base and fix it in place. Align the corner of the burette base opposite the red wind direction point on the probe with the position of the measurement point laid on the non-stick tape. Rotate the anemometer probe connector appropriately so that it corresponds to the position of the anemometer connector and then connect it to the anemometer, press and hold the [POWER] key of the anemometer for about 2 seconds, the instrument can be switched on, when the instrument is in the "normal mode" screen, the upper right corner of the display shows "5m/s " for the wind speed range, each time you press the [RANGE] key, the range from 5m/s, 50m/s and AUTO respectively to switch, select "5m/s" range file; press the [FAST/SLOW] key, select "SLOW "Press the [MAX/MIN] key to select the "AVG" average function. Press [MAX/MIN] key to select "AVG" average function. Measure the measuring points in the order of laying number, the red wind direction point on the anemometer probe moves to the position of the laid measuring point within 5~10 seconds, press "HOLD" key, the wind speed value remains unchanged when reading and recording. 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. When the measurement is complete, the anemometer can be switched off in any measurement mode by pressing and holding the [POWER] key for about 4 seconds.
According to YY 0569-2005 5.4.7 standard "The average velocity of the falling airflow of a Class II safety cabinet shall be between (0.25 ~ 0.5) m/s; the average velocity of the falling airflow of a safety cabinet shall be between ± 0.15 m/s of the nominal value; for a safety cabinet with uniform falling airflow, the difference between the measured value and the average velocity at each measuring point shall not exceed ± 20% or ± 0.09 m/s. 0.09 m/s (whichever is greater)." The measurement results are evaluated and a conclusion is given as to whether they pass or not.

In the previous:Detection of inflow airflow velocity in biosafety cabinets The next article:What material is cost-effective for constant temperature ovens
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