Labconco Purifier Filtered PCR Enclosures 3970425 - Manual (Page 16)

Chapter 3: Getting Started
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Setting the Downflow Velocity with the
Speed Control
Adjustment of the speed control gives the correct downflow velocity and is located
behind the front panel. The downflow velocity should be from 30-65 fpm for
Class 100 (ISO Class 5) conditions. ISO Class 5 clean air conditions are
maximized at a setting within this range. The Filtered PCR Enclosure is factory
set at 40-55 fpm downflow velocity. (Consult your Safety Officer for airflow
recommendations for your application). Working at the lowest downflow
velocity appropriate for the application will give the quietest operation. Downflow
velocity measurements are made using an anemometer. An electric anemometer
can be obtained from your laboratory supply dealer. Downflow velocity
measurements should be taken 6" below the interior upper diffuser. Using a small
Phillips screwdriver, adjust the speed control to give the required downflow
velocity. See Figures 6-1 and 6-2 in Chapter 6 to locate the speed control. The
downflow velocity is increased by turning the speed control counterclockwise and
clockwise to decrease downflow velocity.
Validating the Filtered PCR Enclosure
To determine the actual downflow velocity, airflow velocity readings are taken.
This should be done 6" down from the upper diffuser located inside the top of the
enclosure. The “average downflow velocity” is achieved by averaging the
readings in the downflow test grid for each model:
The downflow test grid consists of 9 test points, 3 points in 3 rows. The back row
of the grid is 6" from the rear of the work area. The middle and front rows are
6.57" apart from the back to the front. The first and last column of the downflow
grid are spaced 6" in from each sidewall with a center column spaced 5.32" away
from the first and last column.
The downflow test grid consists of 12 test points, 4 points in 3 rows. The back row
of the 6" from the rear of the work area. The middle and front rows are 6.57" apart
from the back to the front. The first and last column of the downflow grid are
spaced 6" in from each sidewall with two columns spaced 7.54" away from the
first and last column.
The downflow test grid consists of 15 test points, 5 points in 3 rows. The back row
of the grid is 6" from the rear of the work area. The middle and front rows are
6.57" apart from the back to the front. The first and last column of the downflow
grid are spaced 6" in from each sidewall with three columns spaced 8.66" away
from the first and last column.
Refer to table in Chapter 2 Refer to the exhaust specification for proper airflow
volumes and downflow velocities for your particular model. A certified technician
should complete validation.
4'
2'
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