Forma Series II 3110 Water-Jacketed co2 Incubators User Manual

The 3100 Series incubators can be equipped with a humidity sensor to
monitor the relative humidity (RH) inside the chamber. The sensor is
mounted to the top air duct and provides a signal that is displayed in 1%
increments on the control panel. The humidity readout can be displayed
continuously or toggles with the temperature readout. In addition, a low
alarm limit can be set on the humidity readout which will detect when the
humidity pan runs dry.  Refer to Section 3, Configuration.
Factors Affecting Humidity Level in Chamber:
•
Water level in the humidity pan
•
Frequency of door openings
•
Humidity pan location; floor, shelf, in duct
•
Air leakage through the gaskets
•
Gas sample port capped
•
N
2
purge on incubators with O
2
control.
•
Humidity levels in O
2
units (Models 3130/3131, 3140/3141) will be
reduced, depending on the amount of N
2
required to control the O
2
level in the chamber. 
The following table lists some typical RH levels at different O
2
and CO
2
percentages.
Table 6-2. Typical RH levels
Incubators equipped with a Thermal Conductivity CO
2
sensor rely on a
constant level of relative humidity in order to accurately measure and
control the CO
2
concentration in the incubator.
The sensor is capable of measuring relative humidity from 10% to 100%
with an accuracy of ±5% above 90%. See Section 2, Calibration for details
on calibrating the humidity readout.
Water Jacketed CO2 Incubator        6-7
Thermo Scientific
Section 6
Factory Installed Options
Humidity Readout
(190643)
O2%
CO2%
RH% (±5%)
1%
2.5%
55%
2%
5%
60%
5%
10%
75%
10%
10%
80%
21%
5%
95%

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Note For customer convenience, 12 ft. of  3/8” I.D. vinyl tubing with 4
clamps is included in the shipping materials. 
▲
The operating (setpoint) temperature range of the incubator with the
cooling coil installed is from +5°C above ambient down to +15°C.
The cooling coil incubator incorporates a finned, U-shaped copper pipe
installed within the water jacket. This pipe routes chilled water supplied by
a laboratory bath. (Be aware that your bath may not be set to restart after a
power failure. Read the manufacturer’s operating instructions.)
Verify that the supply line pressure does not exceed 20 psig (138KPa).
When the cooling coil is in use, several factors affect the uniformity inside
the incubator chamber: the temperature difference between the operating
temperature set point and the bath water temperature; the flow rate of the
chilled water, and the on-time percentage of the door heaters.
As determined in carefully controlled laboratory tests, the smaller the
difference between the temperature of the bath and the setpoint
temperature of the incubator, the better the uniformity. However,
decreasing this temperature difference does cause less control of the system
because if the bath does not cool the water jacket adequately, the heaters
do not cycle and the chamber temperature simply drifts with the ambient
temperature of the room. 
Tests have shown that as a starting point, operating the bath at 2°C to 3°C
below the incubator’s operating setpoint temperature, with a cooling water
flow rate of 1/2 to 1 GPM (gallons per minute), should result in good
control and uniformity.
Because of the efficiency of the cooling coil design, it is possible for
condensation to occur on the outside of the incubator’s water jacket when
operating in certain ambient temperature and relative humidity conditions.
The condensation will then saturate the fiberglass insulation between the
water jacket and the incubator cabinet.
6-8
Water Jacketed CO2 Incubator
Thermo Scientific
Section 6
Factory Installed Options
Cooling Coil

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Using psychometric data from the Carrier Psychometric Chart, curves of
maximum allowable RH versus ambient temperature can be plotted for
different incubator/bath conditions (refer to Figure 6-7). 
Figure 6-7. RH Limits to Avoid Water Jacket Condensation 
For example, if the bath is to be operated at 15°C and the ambient
temperature is about 28°C, the RH in the room must be less than 45% to
avoid condensation forming between the chamber water jacket and the
outside of the cabinet.
Hose barbs are factory installed into the fittings on the back of the cabinet,
as shown below. They can be used as the water inlet or outlet to the bath.
Locate the vinyl tubing and hose clamps shipped inside the incubator. Cut
the tubing in half. The bath can be located up to six feet from the
incubator.
Figure 6-8. Back of Unit
Water Jacketed CO2 Incubator        6-9
Thermo Scientific
Section 6
Factory Installed Options
Installing Cooling Coil
Incubator

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Section 7  
Specifications
*Specifications are based on nominal voltages of 115V or 230V 
in ambients of 22°C to 25°C.
Temperature
Control
±0.1°C
Range
+5°C above ambient to +55°C (131°F)
Uniformity
±0.2°C @ +37°C
Tracking Alarm
User programmable high/low
Temperature Safety
Sensor
Precision thermistor
Controller
Independent analog electronic
Setability
0.1°C
CO
2
/O
2
CO
2
/O
2
Control
Better than ±0.1%
CO
2
Range
0-20%
O
2
Range
1-20%
Inlet Pressure
15 PSIG (1.034 bars), ±5 PSIG
CO
2
Sensor
T/C or IR
O
2
Sensor
Fuel Cell
Readability
0.1%
Setability
0.1%
Tracking Alarm
User programmable
Humidity
RH
Ambient to 95% @ +37°C (98.6°F)
Humidity Pan
0.8 gal. (3 liters) standard
Optional
Display in 1% increments
Fittings
Fill Port
3/8” barbed
Drain Port
1/4” barbed
Access Port
1-1/4” (3.18cm) removable neoprene plug
CO
2
Inlet
1/4” hose barbed
Water Jacketed CO
2
Incubator        7-1
Thermo Scientific

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