Introduction to the detection method of biological safety cabinet
1. The integrity of high efficiency filter
a) Run the fans and lights of the safety cabinet and remove the diffuser and protective cover of the filter. Install the aerosol generator and introduce the aerosol into the safety cabinet to generate an evenly distributed airflow upstream of the high-efficiency filter.
b) Turn on the aerosol photometer and make adjustments; test the upstream airflow of the high-efficiency filter containing aerosol, and there should be at least 20ug/L PAO.
c) The photometer probe should be no more than 25mm from the filter surface downstream of the filter, and moves at a scan rate of less than 50mm/s, so that the probe scans the entire downstream side of the filter and the edge of each combined filter, and scans the test route should overlap slightly.
2. The noise
a) Turn on the fan and lighting of the safety cabinet, and measure the noise at a position 300mm horizontally outward from the center of the safety cabinet and 380mm above the work surface;
b) Turn off the fans and lights of the safety cabinet, if there is an outdoor exhaust fan, let it continue to run, and measure the background noise at the same location;
3. The illumination
a) On the worktable, set illuminance measurement points along the line connecting the center of the two inner side walls of the worktable, the distance between the measurement points does not exceed 300mm, and the minimum distance from the sidewall is 150mm;
b) Turn off the lights of the safety cabinet, and measure the background illuminance at the measurement points sequentially from one side. The average background illumination should be 110lx±50lx;
4.The velocity of downward airflow
Determine the position of the measurement point on a horizontal plane 100mm higher than the upper edge of the front window operation port above the working area, and measure the downdraft flow velocity across the plane at multiple points;
a) The measurement points are equally spaced, and the square grid formed is not larger than 150mm×150mm. There should be at least 3 rows of measurement points, and each row should have at least 7 measurement points;
b) The distance between the boundary of the test area and the inner wall of the safety cabinet and the operation opening of the front window should be 150mm.
5. The velocity of inflow airflow
Measure the flow rate of exhaust air to determine the flow rate of inflow air (suitable for Class II A1, A2 safety cabinets)
a) Use a thermal anemometer to measure the airflow velocity across the exhaust filter surface at multiple points. The measurement point is a grid point not larger than 100mm × 100mm, the boundary point is 100mm from the edge of the filter, and the distance between the measurement surface and the filter surface about 100mm;
b) Calculate the average exhaust flow rate of each measuring point to be the average exhaust flow rate (m/s), and multiply the average exhaust flow rate by the exhaust area (m2) to obtain the exhaust flow rate (m3/s);
c) The exhaust flow rate (m3/s) is divided by the front window operating port area (m2) to obtain the average inflow airflow velocity (m/s);
6. The airflow mode of working window
6.1 Downdraft test
The smoke is along the centerline of the work surface, at a height of 100mm above the top of the front window operating opening, from one end of the safety cabinet to the other.
6.2 The test of observation window airflow
The smoke is 25mm behind the observation screen and 150mm above the top of the front window operation port from one end of the safety cabinet to the other.
6.3 Airflow test at the edge of the front window operating opening
The smoke passes along the entire perimeter of the front window operating opening approximately 38mm outside the safety cabinet, paying particular attention to corners and vertical edges.
7. The number of suspended particles, planktonic bacteria
The specific detection method is the same as the comprehensive performance detection method of the clean room.