Downflow Velocity - Labconco Logic+ A2 Technical Manual

Downflow Velocity

All models of Labconco biosafety cabinets are classified as uniform downflow, as tested
per the current NSF Standard 49. This section describes how to prepare and test the
downflow velocity on all Types of biosafety cabinets.
Before setting up the downflow velocity test, if any accessories are installed inside the
biosafety cabinet (UV lamp, IV Bar, etc.), remove them for this test. Ensure sash is at
the correct operating height, and remote (building) exhaust is on (if exhaust connected).
On all biosafety cabinet types and models, the downflow test points are to be taken at a
height of 4 inches (10 cm) above the bottom edge of the glass sash.
The thermal anemometer probe should always point toward the nearest side wall
or the sash, whichever is closer to the probe. Therefore, on the two rear rows, the
probe should point to the left side wall when taking the left half of test points, and the
right side wall when taking the right half of test points. And, on the front row, the probe
should always point forward towards the glass sash. See Figures 10-26 and 10-27 for
reference.
Figure 10-26 Figure 10-27
The thermal anemometer probe stand shown in the above figures is available from
Labconco. The catalog number for the stand is 3858410.
Set the thermal anemometer's time constant to 10 or 15 seconds for greater data
stability.
1. For the Type and sash height biosafety cabinet under test, set up the test grid
based on the dimensions provided in Table 10-6. Start the blower(s).
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