
Forma® Model 3911/3913_____________________________________________________________Start-Up and Operation
3 - 2
3.2 Setting the Incubator’s Operating Temperature
(Figure 3-5)
The Watlow temperature
controller’s upper numerical
display shows the actual temperature
inside the incubator chamber. The
lower display shows the temperature
setpoint.
Changing the Setpoint
To raise or lower the set-
point, press the up or down
arrow. Temperatures are set in .1°C
increments.
3.3 Setting the Incubator’s Operating Humidity
(Figure 3-6)
The Watlow humidity
controller’s upper numerical
display shows the actual humidity inside
the incubator. The lower display shows
the humidity setpoint.
To raise the setpoint, press the
up or down arrows. Humidity is set
in one percent increments.
3.4 Programming the controllers
The Watlow temperature and humidity controllers have
been set at the factory to operate the incubator within the speci-
fications listed in Section 6 of this manual. Reference copies of
the Watlow configuration records are included at the end of
Section 2 of this manual.
To prevent tampering, mechanical and software lockouts
are employed in the system. These lockouts must only be
removed by persons skilled in configuring controller software.
Making program changes to either the tempera-
ture or humidity controllers will seriously alter the
performance of the incubator and therefore must
be made only by qualified persons. The con-
trollers should not be re-configured without first
consulting Forma Scientific Service Department,
at 1-888-213-1790.
Dehumidify Switch and Indicator (Figure 3-3)
The dehumidify switch will enable the refrigeration
system if the refrigeration switch is currently off. When
controlling humidity, the dehumidification switch should be in
the ON position for most applications. The dehumidification
light will cycle on and off as the humidity controller toggles
between umidify and dehumidify. The dehumidify light will be
de-energized when the system is in Defrost mode.
Humidity is removed from the cabinet by the refrigeration
evaporator coil. Moisture accumulates on the coil and is collect-
ed into the evaporator pan. The accumulated moisture is then
plumbed to the back of the cabinet, which can be emptied to a
floor drain, or an evaporative device.
Audible Humidity Alarm and Indicator Display (Figure 3-3)
The humidity alarm is a function of the humidity con-
troller, Figure 3-4. When the cabinet humidity goes outside
the set parameters of the controller, L3 indicator on the con-
troller lights, the audible alarm sounds, and the humidity alarm
indicator (Figure 3-3, Item I) on the control panel lights.
Hold/Run Key
Pressing the Hold/Run key
(Figure 3-4) on the controller
silences the audible alarm and
extinguishes the humidity alarm indi-
cator and the L3 indicator on the con-
troller. A3HI/A3LO flashes on the
lower display until the cabinet humid-
ity returns to the system setpoint.
Note: The humidity controller’s high
and low limits are set by the factory
at 100% and 0%. Therefore, the sys-
tem will go into the alarm state when
the humidity exceeds these percentages by one percent. When
operating the incubator near these high or low humidity levels,
frequent alarms may occur. This will require that the con-
troller’s high or low limit be reset to three or four percent over
the high limit, or three or four percent under the low limit.
Refer to the Watlow User’s guide provided. Refer also to the
factory configuration records located at the end of Section 2 of
this manual.
I
J
KL
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H
J
Figure 3-4
K
L
M
Figure 3-5
NO
P
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Figure 3-6