Forma Scientific, Inc.___________________________________________________Operation
4-2
d. Alarm By-Pass Switch (Sliding Window Models Only)
The Alarm By-Pass switch silences the audible Window Above 10 Inch alarm for five
minutes. The red visual indicator remains illuminated. The alarm rings-back to remind the
operator that the window is still open more than 10 inches.
e. Static Pressure Gauge (In. W.G.)
The static pressure gauge measures the air
pressure differential across the filters providing an
indication of filter "loading". As the filters become
loaded, resistance increases and the reading on the static
pressure gauge increases accordingly. When the reading
increases by 50% from original measurement, cabinet
airflow should be checked with a thermoanemometer.
Replace the filters if proper airflow cannot be obtained.
Note: The static pressure gauge should not be used as a direct measure of airflow.
f. Blower Speed Control
The blower speed control, located on the top left back side of the control panel, is used
to adjust the air velocity from the internal blower motor. The blower speed is adjusted by turning
the screw on the variable resistor mounted on the curcuit board adjacent to the controller. (Refer
to the drawing following.) Turning the screw clockwise increases air velocity; counterclockwise
decreases it.
The blower speed is factory set and should only be changed by a qualified technician.
WARNING! Live voltage is present on the control terminals of the switches and dials on the
front of the blower panel. Avoid touching these controls when reaching into the drawer and
making any adjustments.
Blower Receptacles
Window
above 10 in.
Alarm
BypassLights
on onon
U.V.
off
1
.
5
1.0
1
.
0
0
2
.
0
Figure 4-2
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