Thermo Electron 3940 Series Operating instructions

Analyze • Detect • Measure • Control™
Model 3940 Series
Forma Environmental Chamber
Operating and Maintenance Manual
7043940 Rev. 7

Thermo Electron CorporationThermo Electron Corporation
MANUAL NUMBER 7043940
7 23451/IN-3294 4/6/06 Changed to 15, ±5 PSIG and specified range in required CO2pressure regulation ccs
6 22678/IN-3229 1/17/05 Remove 270129 from terminals 15 and 16 of temperature control aks
-- 22672/IN-3227 1/17/05 Revised steam generator wiring aks
5 22454/IN-3208 9/14/04 Watlow SD 4-20mA standard; new schematics, configuration sheet ccs
-- 22452/IN-3208 9/14/04 Added noise reducing filters to Watlow 982 controllers, new schematics ccs
4 22453/IN-3208 9/7/04 Updated FLA specs on drawings and specification page ccs
-- -- 8/18/04 Added Puregas dryer preventive maintenance ccs
3 -- 6/28/04 Reinstalled reference to Hold/Run key for silence on Watlow, corrected ccs
2 22337 5/11/04 Removed reference to Hold/Run key for silence on Watlow, chg pending ccs
1 22070/22129 1/29/04 Pre-programmed controller/changed thermal fuse aks
-- -- 1/26/04 Updated section 3.1.E dehumidification aks
-- 20843 11/20/03 Release 9 aks
REV ECR/ECN DATE DESCRIPTION By
Preface
Model 3940 Series i
Model Capacity
(cu. ft.) Voltage
3911 11 208-220
3913 11 220-240
3940 29 208-220
3949 29 220-240
Table 1. Models Covered in This Manual

Thermo Electron Corporationii Model 3940 Series Thermo Electron Corporation
Preface
Important Read this instruction manual. Failure to read, understand and follow the instructions in this manual
may result in damage to the unit, injury to operating personnel, and poor equipment performance. V
Caution All internal adjustments and maintenance must be performed by qualified service personnel. V
Material in this manual is for information purposes only. The contents and the product it describes are subject to
change without notice. Thermo Electron Corporation makes no representations or warranties with respect to this
manual. In no event shall Thermo be held liable for any damages, direct or incidental, arising out of or related to
the use of this manual.
©2003 Thermo Electron Corporation. All rights reserved.

Thermo Electron Corporation Model 3940 Series iiiThermo Electron Corporation
Preface
Important operating and/or maintenance instructions. Read the accompanying text carefully.
Potential electrical hazards. Only qualified persons should perform procedures associated with this
symbol.
Equipment being maintained or serviced must be turned off and locked off to prevent possible injury.
Hot surface(s) present which may cause burns to unprotected skin, or to materials which may be
damaged by elevated temperatures.
Marking of electrical and electronic equipment, which applies to electrical and electronic equipment
falling under the Directive 2002/96/EC (WEEE) and the equipment that has been put on the market
after 13 August 2005.
This product is required to comply with the European Union’s Waste Electrical & Electronic
Equipment (WEEE) Directive 2002/96/EC. It is marked with the WEEE symbol. Thermo Electron
has contracted with one or more recycling/disposal companies in each EU Member State European
Country, and this product should be disposed of or recycled through them. Further information on
Thermo Electron’s compliance with this directive, the recyclers in your country and information on
Thermo Electron products will be available at www.thermo.com.
Always use the proper protective equipment (clothing, gloves, goggles, etc.)
Always dissipate extreme cold or heat and wear protective clothing.
Always follow good hygiene practices.
Each individual is responsible for his or her own safety.

Thermo Electron Corporationiv Model 3940 Series Thermo Electron Corporation
Preface

Thermo Electron Corporation Model 3940 Series vThermo Electron Corporation
Preface
Warranty Notes
Information You Should Know Before Requesting Warranty Service
•Locate the model and serial numbers. A serial tag is located on the unit itself and on the operating manu-
al shipped with the unit.
• For equipment service or maintenance, or with technical or special application inquiries, contact Technical
Services at 1-888-213-1790 or 1-740-373-4763 (USA and Canada). Outside the USA, contact your local distrib-
utor.
Repairs NOT Covered Under Warranty
• Calibration of control parameters. Nominal calibrations are performed at the factory; typically ±1°C for
temperature, ±1% for gases, and ±5% for humidity. Our service personnel can provide precise calibrations as
a billable service at your location. Calibration after a warranty repair is covered under the warranty.
• Damage resulting from use of improper quality water, chemicals or cleaning agents detrimental to
equipment materials.
• Service calls for improper installation or operating instructions. Corrections to any of the following are
billable services:
1) electrical service connection
2) tubing connections
3) gas regulators
4) gas tanks
5) unit leveling
6) room ventilation
7) adverse ambient temperature fluctuations
8) any repair external to the unit
• Damage resulting from accident, alteration, misuse, abuse, fire, flood, acts of God, or improper
installation.
• Repairs to parts or systems resulting from unauthorized unit modifications.
• Any labor costs other than that specified during the parts and labor warranty period, which may
include additional warranty on CO2sensors, blower motors, water jackets, etc.

Model 3940 Series viThermo Electron Corporation
Table of Contents
Installation and Set-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1
Preliminary Cleaning and Disinfecting . . . . . . . . . . . . . . . . . . . . . . . .1-1
Installing the Shelves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1
Leveling the Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-1
Connect Water Inlet for Humidity System . . . . . . . . . . . . . . . . . . . . .1-2
Alternate Water Supply for Humidity System . . . . . . . . . . . . . . . . .1-3
Connect Drain Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
4-20 Milliamp Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-3
Remote Alarm Contacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
Power Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4
Set the Overtemp Safety Thermostat . . . . . . . . . . . . . . . . . . . . . . . . .1-5
Set the Undertemp Safety Thermostat . . . . . . . . . . . . . . . . . . . . . . . .1-5
Cobex Recorder (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6
Change the Chart Paper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6
Change the Pen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-7
Honeywell Recorder (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-7
IR CO2Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-7
Connect the CO2Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-7
Set the CO2Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-8
CO2Control and Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-9
Start-Up and Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1
Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1
Set the Operating Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-4
Set the Operating Humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-4
Air Exchange Ventilator Caps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5
Heatless Dryer (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5
Section 1
Section 2

vii Model 3940 Series Thermo Electron Corporation
Routine Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1
Maintaining the Humidity Generator . . . . . . . . . . . . . . . . . . . . . . . .3-1
Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-2
Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1
Access Electrical Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-1
Over/Undertemp Probe and Thermostat . . . . . . . . . . . . . . . . . . . . . .4-1
Humidity/Temp Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-2
Program Humidity/Temp Controllers . . . . . . . . . . . . . . . . . . . . . . . .4-3
Remove Mechanical Lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-3
Remove Software Lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-4
Controller Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5
Offset Calibration (Temp/Humidity) . . . . . . . . . . . . . . . . . . . . . . .4-5
Replace Optional Recorder and Probe(s) . . . . . . . . . . . . . . . . . . . . . .4-7
Calibrate the Recorder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-7
Set Door Heater Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-8
Clean/Adjust Steam Generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-8
CO2Controller Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-10
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1
Spare Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-1
Refrigeration Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-1
Electrical Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-1
Warranty Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-1
Table of Contents
Section 3
Section 4
Section 5
Section 6
Section 8
Section 7
Section 9

Leveling the Unit
Model 3940 Series 1-1Thermo Electron Corporation
Section 1 Installation and Set-Up
Locate the unit on a firm, level surface in an area of minimum ambient
temperature fluctuation. A minimum of three (3) inches of clearance is
required at the top and back of the incubator. This space is necessary to
allow adequate airflow around the refrigeration system. At least eight (8)
inches clearance above the cabinet is required for service access.
Disinfect all interior surfaces with a general-use laboratory disinfectant.
Rinse thoroughly with sterile distilled water, then 70% ethanol. Dry with a
sterile cloth as needed.
Disinfect the shelf channels and shelves, then rinse with distilled water
before installing.
Caution Before using any cleaning or decontamination method except
those recommended by the manufacturer, users should check with the
manufacturer that the proposed method will not damage the equipment. V
Warning Accidental spills of hazardous materials on or inside this unit are
the responsibility of the user. V
The shelves may be installed at any level
in the incubator. Install a shelf channel
on each side. With the tabs pointing up,
attach the channel by locating the rivet
into a slotted hole, far end first. Pull the
channel toward the front and slide the
front rivet on the channel into the slotted
hole and press down. Make sure that the
channels are opposite each other so that
the installed shelf will be level.
Place a bubble-type level on a shelf inside the incubator. Adjust the feet as
needed; counterclockwise to lengthen or clockwise to shorten. Level the
unit front-to-back and left-to-right.
Installing the Shelves
Preliminary Cleaning
and Disinfecting
Figure 1-1. Install Shelf Channel

1-2 Model 3940 Series Thermo Electron Corporation
Section 1
Installation and Set-Up
Thermo Electron Corporation
The humidity reservoir will require approximately three cups (0.710 liter)
of water on the initial filling. For best operation of the incubator, sterilized
distilled, demineralized or de-ionized water should be used in the humidity
reservoir. Water purity should be in the resistance range of 50K to 1M
Ohm/cm, or a conductivity range of 20.0 to 1.0 uS/cm. Refer to ASTM
Standard D5391-93 or D4195-88 for measuring water purity.
Distillation systems, as well as some types of reverse osmosis water purity
systems, can produce water in the quality range specified. Tap water is not
recommended as it may contain chlorine, which can deteriorate the
stainless steel. Tap water may also have a high mineral content, which
would produce a build-up of scale in the reservoir. High purity, ultra pure
or milli-q water is not recommended as it is an extremely aggressive solvent
and will deteriorate the stainless steel. High purity water has a resistance of
above 1M to 18M Ohm. Even high purity water can contain bacteria and
organic contaminants. Water should always be sterilized or treated with a
decontaminant, safe for use with stainless steel as well as safe for the
product, prior to being introduced into the humidity reservoir.
Caution Distilled or de-ionized water used in the humidity reservoir must
be within a water quality resistance range of 50K to 1M Ohm/cm to
protect and prolong the life of the stainless steel. Use of water outside the
specified range will decrease the operating life of the unit and may void
warranty. V
The water inlet is the 1/8” FPT connection located on the rear top center
of the incubator. A 1/4” hose fitting is provided for a hose connection, if
desired. Water inlet pressure must not exceed 40 PSI. A manual shut-off
valve should be installed between the main water supply and the incubator.
Caution To prevent mineral buildup on humidity generator walls, it may
be necessary to clean the humidity generator with a non-metallic abrasive
pad and flush thoroughly every two to three months. Refer to Section 4,
Cleaning the Humidity Steam Generator. V
Connect Water Inlet
for Humidity System

4-20 Milliamp Output
Connect Drain Line
Model 3940 Series 1-3Thermo Electron Corporation
Section 1
Installation and Set-Up
If an in-house water supply of the required purity range (50K to 1M
Ohm) is not available, an alternate water supply method can be used. A
large vented carboy (5 gal. minimum) of water in the required purity range
can be placed on top of the unit. Connect it to the 1/8” FPT water inlet
fitting, located on the rear top center of the incubator.
Note The maximum water consumption of this incubator could be as high
as 2 gallons per day. When using an alternate water supply method, it is
recommended that the supply be checked periodically based on source
volume. V
The cabinet’s 3/8” MPT drain line connection is located
on the rear (lower left side) of the cabinet. A P-trap
(Figure 1-2) is included with the unit and must be
installed on the connection.
To install the drain connection:
1. Using Teflon pipe thread tape, tape the threads on the cabinet drain
connection.
2. Using an open end adjustable wrench, install the P-trap onto the
connection. Make sure the trap section is positioned down.
3. Push a piece of 3/8” ID tubing onto the trap and direct the tubing to a
convenient drain. Install a hose clamp on the tubing, if desired. A
condensate evaporator (P/N 1900031) or condensate pump (P/N
184062) may also be used.
The environmental chamber is equipped with 4-20mA output for the
remote transmission of temperature, humidity and CO2data. A terminal
strip is located on the back of the incubator for convenience. Refer to
Figure 1-3 for terminal pin identification.
Figure 1-2. P-Trap
Figure 1-3. Terminal Pin Identification
Alternate Water Supply for
Humidity System

Remote alarm connections are also included on the terminal strip (Figure
1-3) providing Normally Open (N.O.) and Normally Closed (N.C.)
contacts. C is the Common terminal. The remote alarm will activate when
either the incubator’s temperature, humidity, or CO2go out of the set
alarm limits.
See the serial tag on the side of the unit for electrical specifications, or refer
to the electrical schematics at the end of this manual.
Caution Connect the incubator to a grounded, dedicated circuit. For
Models 3911 and 3940, the power cord connector is the mains disconnect
device. Models 3913 and 3949 have a fusable disconnect located on the
back of the unit. Position the incubator so the unit can be easily
disconnected. V
For Models 3911 and 3940, plug the provided 10 ft. power cord with the
NEMA 14-20 plug into the grounded dedicated electrical circuit.
When the humidification system is operational, the incubator may be
started. Preset the controls as follows:
Overtemp Safety Thermostat . . . . . . Fully Clockwise
Undertemp Safety Thermostat . . . Fully Counterclockwise
Main Power Switch . . . . . . . . . . . . . . . . . . . . . . .ON
Humidity Controller . . . . . . . . . . . .Desired Setpoint
Temperature Controller . . . . . . . . . .Desired Setpoint
Door Heater . . . . . . . . . . . . . . . . . .40% (factory set)
For best overall performance of the incubator, the refrigeration switch
should be turned On for most applications. When running Low or No
humidity at high temperatures, the refrigeration switch may be turned Off.
Caution The defrost switch must be turned on when the temperature
setpoint is 10°C, or below. V
1-4 Model 3940 Series Thermo Electron Corporation
Section 1
Installation and Set-Up
Remote Alarm
Contacts
Power Connection
Start-Up

Set the Undertemp
Safety Thermostat
Allow the chamber temperature and humidity to stabilize then set the
overtemp safety thermostat as follows:
1. Turn the overtemp control knob slowly counterclockwise until the
audible alarm sounds and the overtemp indicator lights.
2. Turn the overtemp control knob clockwise at least 2°. The alarm
should be silenced and the overtemp indicator light should go out. The
overtemp safety thermostat is now set a few degrees above the control
temperature setpoint. When the chamber temperature rises to the
overtemp control point, the alarm system will activate, power to the
heaters will shut off, and the chamber temperature will be maintained
at the overtemp control point.
When an overtemp condition occurs, the cause must be determined and
corrected before normal operation under the main temperature controller
can be resumed.
Note When the chamber temperature control setpoint is changed, the
overtemp safety thermostat must be reset to accommodate the change. V
Note The overtemp control is not directly calibrated. The numbers on the
dial are for reference only. V
Allow the chamber temperature and humidity to stabilize, then set the
undertemp safety thermostat as follows:
1. Turn the undertemp control knob slowly clockwise until the audible
alarm sounds and the undertemp indicator lights.
2. Turn the undertemp control knob counterclockwise at least 2° on the
scale. The alarm will silence and the undertemp indicator light go out.
The undertemp safety thermostat is now set a few degrees below the
control temperature setpoint. When the chamber temperature drops to the
undertemp control point, the alarm system activates, power to the
compressor shuts off, and the chamber temperature is maintained at the
undertemp control point.
When an undertemp condition occurs, the cause must be determined and
corrected before normal operation under the main temperature controller
can be resumed.
Model 3940 Series 1-5Thermo Electron Corporation
Section 1
Installation and Set-Up
Set the Overtemp
Safety Thermostat

Change the Chart Paper
Note When the chamber temperature control setpoint is changed, the
undertemp safety thermostat must be reset to accommodate the change. V
Note The undertemp control is not directly calibrated. The numbers on
the dial are for reference only. V
The seven-day circular chart recorder is located on the front of the
incubator cabinet and is protected by a glass door.
To prepare the recorder for
operation, open the glass door and
snap the connector onto the 9V
battery (Figure 1-4). If the unit is
operating, the green LED lights
steady. If the unit is not turned on,
the LED blinks.
If the battery is weak or not
connected, the green LED will flash.
If power is lost to the cabinet, the
LED will also flash. When replacing
the 9V battery, use only an alkaline
style battery. Dispose of the old
battery following established
environmental practices.
1. Press the Change Chart button (#3) and hold it for 1 second until the
pen begins to move to the left of the chart. See Figure 1-4.
2. Remove the existing chart by unscrewing the center knob securing it.
3. Install the new chart, positioning it so that the correct time line
coincides with the time line groove on the chart plate.
4. Replace the center knob and screw it tightly against the chart.
1-6 Model 3940 Series Thermo Electron Corporation
Section 1
Installation and Set-Up
Set Undertemp Safety
Thermostat (cont’d)
Figure 1-4. Install Battery In Recorder
Cobex Recorder
(Optional)

IR CO2Option
Honeywell Recorder
(Optional)
1. Using a small flat blade screwdriver, loosen the 2 screws holding the
pen arm and remove the pen and arm as an assembly.
2. Unsnap the plastic hinge securing the pen. Remove and discard the old
pen.
3. Install the new pen by snapping the hinge securely around the pen
arm.
4. Re-install the pen assembly by sliding the pen arm under the screws,
positioning the pen tip in the time line groove. Tighten the screws.
5. Push the Chart Change button and hold it for 1 second until the pen
begins to move back onto the chart.
Note Make sure that the pen is marking on the chart. It may be necessary
to gently lift the pen onto the chart paper. V
The Honeywell, DR 4500 Recorder is a one to four-channel
microprocessor-based, circular chart recorder.
The recorder is capable of recording both temperature and humidity and
printing alphanumeric chart data on blank heat-sensitive chart. Refer to
the Honeywell Configuration Record at the end of Section 4 and the
supplemental Honeywell Recorder manual.
This section applies to units with the IR CO2option only.
For the most economical use, the liquid CO2supply tanks should be
without siphon tubes, so that only CO2gas enters the incubator injection
system. Two tanks may be joined together with a manifold to ensure a
continuous CO2supply.
Install a two-stage pressure regulator, with indicating gauges, at the supply
cylinder outlet. The high-pressure gauge should have an indicating range
of 0 to 2000 psig to monitor tank pressure. The low-pressure gauge should
have an indicating range of 0 to 30 psig to monitor input pressure to the
incubator injection system. A suitable two-stage pressure regulator is
available.
Model 3940 Series 1-7Thermo Electron Corporation
Section 1
Installation and Set-Up
Change the Pen
Connect the CO2Source

The CO2source must be regulated at a pressure level of 15, ±5 psig.
Higher pressure levels may damage the CO2control system. The user
should determine the most economical pressure level, between 10 and 20
psig appropriate for the desired CO2percentage in the chamber. Use only
sufficient pressure to maintain recovery time after door openings.
To connect the CO2supply (Figure 1-5):
1. Connect the CO2tubing to the 1/4”
hose fitting installed in the CO2inlet.
2. Check the tubing connection for leaks.
The Watlow SD CO2controller's upper display shows the actual CO2
content inside the chamber. The lower display shows the CO2setpoint.
Before setting the CO2content, allow the chamber temperature and
humidity to stabilize. Do not open door during the stabilization period.
To set the CO2content (0% to 20%), press the Up or Down Arrow keys
on the Watlow SD Controller.
1-8 Model 3940 Series Thermo Electron Corporation
Section 1
Installation and Set-Up
Connect the CO2Source
(continued)
Figure 1-5. Inlet Connections
Set the CO2Content
Figure 1-6. Watlow SD Control

Sample Port
The sample port is used for checking CO2percentage in the incubator
chamber by an independent test instrument (such as with a Fyrite, or
similar CO2test instrument).
Caution To prevent CO2loss, the sample port must be capped when it is
not in use. V
CO2Alarm
The CO2alarm is factory set to activate when the chamber CO2content
deviates from configured alarm set points (see configuration record).
When a CO2alarm occurs, the CO2Alarm indicator on the control
panel lights and the audible alarm sounds.
The CO2alarm high and low setpoints are established through the
Watlow SD CO2controller (ALO, and AHI). Refer to the Configuration
Record included at the end of Section 4.
Model 3940 Series 1-9Thermo Electron Corporation
Section 1
Installation and Set-Up
CO2Control and Indicators

Model 3940 Series 2-1Thermo Electron Corporation
Section 2 Start-Up and Operation
Figure 2-1. Environmental Chamber Control Panel, Shown with Optional CoBex
Recorder and Optional CO2Control
Main Power Switch and Indicator Light (Figure 2-2)
The main power switch controls power to the incubator. The main
power indicator lights when the power switch is on and the unit is
receiving power.
Refrigeration Switch and Indicator Light (Figure 2-3)
The refrigeration switch controls power to the refrigeration system. The
refrigeration indicator lights when the refrigeration switch is on and the
compressor is receiving power.
Control Panel
Figure 2-2. Main Power Figure 2-3. Switches