Labconco Purifie Horizontal Clean Benches 3970424 - Manual (Page 17)

Chapter 3: Getting Started
Product Service 1-800-522-7658 13
Setting the Downflow Velocity with the
Speed Control Adjustment
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 Vertical Clean Bench is factory set
at 40-55 fpm downflow velocity. (Consult your Safety Officer for airflow
recommendations for your application). Working at the 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 Vertical Clean Bench
To determine the actual downflow velocity, airflow velocity readings are taken.
This should be done 6" down from the top of the interior upper diffuser. 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 the exhaust specifications table in Chapter 2 for proper airflow volumes
and downflow velocities for your particular model. A certified technician should
complete validation.
2'
3'
4'