Labconco Class I Enclosure Models 3980423 - Manual (Page 20)

Chapter 3: Getting Started
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Set the Face Velocity with the Speed
Control Adjustment
Adjustment of the speed control gives the correct face velocity and is located
behind the front panel. The face velocity should be from 75 to 105 fpm for
biohazardous operations. (Consult your Safety Officer for airflow
recommendations for your application). Containment is maximized at a setting
within this range. Working at the lowest face velocity appropriate for the
application will give the quietest operation. Face velocity measurements are made
using an anemometer. An electric anemometer can be obtained from your
laboratory supply dealer. Face velocity measurements should be taken in
accordance with the Industrial Ventilation Manual. Using a small Phillips
screwdriver, adjust the speed control to give the required face velocity. See
Figures 6-1 and 6-2 in Chapter 6 to locate the speed control. The face velocity is
increased by turning the speed control counter clockwise and clockwise to
decrease face velocity.
Validating the Vented Enclosure
To determine the actual face velocity at the sash opening, airflow velocity readings
are taken. This should be done across the sash opening of the enclosure in
accordance with the Industrial Ventilation Manual. (See Appendix E) The
“average face velocity” is achieved by taking readings in two rows across the
enclosure with the readings 6" from the ends and evenly spaced every 12"; the first
row is 3" down from the upper sash foil and the second row is 3" up from the work
surface. A total of four readings will be taken for the 2' enclosure, six readings
taken for the 3' enclosure and eight readings taken for the 4' enclosure and then
averaged. Refer to Chapter 2 for proper airflow volumes for your particular
model.
The Purifier enclosures have been tested at Labconco’s airflow test facility per
ASHRAE 110-1995. All enclosures achieve an “as manufactured rating” of less
than 0.05 part per million (ppm) at 4 liters per minute (lpm); AM <0.05 (Consult
Labconco for individual ratings). For “field use” ASHRAE testing contact
Labconco for a certified on-site contractor. Labconco also performed extensive
ASHRAE testing to validate the enclosures for gas containment. For copies of
these validation reports, contact Labconco Customer Service.
The Purifier Enclosures were also subjected to Biological Containment testing,
using a modified Personnel Protection Test, as described in NSF/ANSI Standard
Number 49. An aerosol challenge of approximately 5 x 10
8 spores of Bacillus
subtilus var Niger were released in the enclosure and appropriate air sampling
equipment established the number of spores that escaped through the sash opening.
Each size enclosure was tested three times. All three sizes of the enclosure were
tested at 75 FPM inflow and typically 1 or less than one spore escaped from the
enclosure during each of the tests.