Labconco 3940200 User Manual - Speed Control Adjustment
21
Chapter 3: Getting Started
230V Models
The same procedure applies for the 230V except it is shipped
without a plug. Install the appropriate plug for your electrical
specifications per local codes.
Set the Face Velocity with the
Speed Control Adjustment
For XPert Filtered Balance Systems, adjustment of the speed
control gives the correct face velocity and is located behind the
front panel. The face velocity should be adjusted from 60 to 100
fpm for weighing 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 XPert 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