Labconco 3980200 User Manual - Speed Control Adjustment

17 

Chapter 3:  Getting Started

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.