TestEquity 123H Operation manual

Copyright © 2009-2015 TestEquity LLC Rev. 2.3, July 17, 2015
Model 123H
Temperature/Humidity Chamber
With F4 Controller and EZ-Zone Limit,
HMM100 Humidity Sensor, W100 Water Recirculation System
Serial Number 230232 and above
Operation and Service Manual
TestEquity LLC
6100 Condor Drive
Moorpark, CA 93021
Support: 877-512-3457 Toll Free
805-480-0638
Corporate: 800-732-3457
805-498-9933
http://www.testequity.com

Table of Contents
Chapter 1 – Safety Instructions________________________________________________1-1
Introduction ____________________________________________________________________1-1
Installation Safety Notices _________________________________________________________1-1
Operation Safety Notices __________________________________________________________1-2
Chapter 2 – Installation ______________________________________________________2-1
Uncrating_______________________________________________________________________2-1
Preparation For Use______________________________________________________________2-1
Installation Location _____________________________________________________________2-2
Humidity Water Connection _______________________________________________________2-3
Plumbed Demineralized Water Installation __________________________________________________ 2-3
Water Recirculation System Installation, Model W100 _________________________________________ 2-3
Water Recirculation System Filter Cartridge Replacement ______________________________________ 2-3
Water Recirculation System Assembly, Model W100 __________________________________________ 2-4
Chapter 3 – Operation _______________________________________________________3-1
Introduction ____________________________________________________________________3-1
Summary of Chamber Operation ___________________________________________________3-1
Front Panel Switches and Lights____________________________________________________3-2
Power Switch _________________________________________________________________________ 3-2
Conditioning Switch – ON Mode __________________________________________________________ 3-2
Conditioning Switch – Event 1 Mode_______________________________________________________ 3-2
Light Switch __________________________________________________________________________ 3-2
Heat Light ____________________________________________________________________________ 3-2
Cool Light____________________________________________________________________________ 3-2
Humidity Enable Light __________________________________________________________________ 3-3
Humidity Light ________________________________________________________________________ 3-3
Loading the Chamber ____________________________________________________________3-4
Performance Considerations ______________________________________________________________ 3-4
Port Plugs ____________________________________________________________________________ 3-5
Avoiding Moisture (non-humidity mode)____________________________________________________ 3-5
Internal Test Fixtures ___________________________________________________________________ 3-5
Chapter 4 – F4 Temperature/Humidity Controller________________________________4-1
Introduction ____________________________________________________________________4-1
Security Features_______________________________________________________________________ 4-1
F4 Controller Keys and Displays ___________________________________________________4-2
Main Page ____________________________________________________________________________ 4-3
Static Set Point Control__________________________________________________________________ 4-4
Humidity Operation______________________________________________________________4-5
Humidity Mode Enable__________________________________________________________________ 4-5
Standard Humidity Range________________________________________________________________ 4-6
Humidity Mode Considerations ___________________________________________________________ 4-6
System Enable Function _________________________________________________________________ 4-8
Event Outputs for Customer Use __________________________________________________________ 4-9
Event Assembly _______________________________________________________________________ 4-9
Purge _________________________________________________________________________4-10
GN2 (Gaseous Nitrogen) Installation ______________________________________________________ 4-10
Dry Air Installation (TE-0017) ___________________________________________________________ 4-10
Purge Operation ______________________________________________________________________ 4-11
Adjusting the Purge Flow _______________________________________________________________ 4-11
Relief Vent __________________________________________________________________________ 4-11

Table of Contents
Profile Programming ____________________________________________________________4-12
Step Types___________________________________________________________________________ 4-12
How to Program a New Profile___________________________________________________________ 4-14
Programming Hints____________________________________________________________________ 4-15
Profile Key __________________________________________________________________________ 4-15
How to Start a Profile __________________________________________________________________ 4-15
How to Hold/Resume a Running Profile____________________________________________________ 4-16
How to Terminate a Running/Holding Profile _______________________________________________ 4-16
How to Delete or Re-Name a Profile ______________________________________________________ 4-16
How to Edit a Profile __________________________________________________________________ 4-17
Profile Examples______________________________________________________________________ 4-18
Operations Page ________________________________________________________________4-19
Setup Page_____________________________________________________________________4-19
Factory Page ___________________________________________________________________4-20
Computer Interface _____________________________________________________________4-20
RS-232C ____________________________________________________________________________ 4-20
Common Modbus Registers _____________________________________________________________ 4-20
GPIB (optional)_______________________________________________________________________ 4-20
Ethernet (optional) ____________________________________________________________________ 4-20
Chapter 5 - Limit Controller __________________________________________________5-1
Introduction ____________________________________________________________________5-1
Limit Controller Keys and Displays ________________________________________________________ 5-2
How to Set the High and Low Temperature Safety Limits_______________________________________ 5-2
Resetting an Out of Limit Condition________________________________________________________ 5-2
Silencing the Audible Alarm______________________________________________________________ 5-2
Protecting an Energized Test Sample _______________________________________________________ 5-3
Chapter 6 – Frequently Asked Questions________________________________________6-1
Chapter 7 – Specifications ____________________________________________________7-1
Model 123H Chamber Specifications ________________________________________________7-1
F4 Controller Specifications _______________________________________________________7-2
Chapter 8 – Maintenance_____________________________________________________8-1
Preventive Maintenance Intervals __________________________________________________8-1
Daily or As Needed_____________________________________________________________________ 8-1
Every 3 Months________________________________________________________________________ 8-1
Every 6 Months________________________________________________________________________ 8-1
Every 12 Months_______________________________________________________________________ 8-1
Maintenance Procedures __________________________________________________________8-2
How to Clean the Chamber Interior and Exterior ______________________________________________ 8-2
How to Listen for Abnormal Noise or Vibration ______________________________________________ 8-2
How to Inspect the Door Seal _____________________________________________________________ 8-2
How to Inspect the Refrigeration Machinery Compartment______________________________________ 8-3
How to Verify the Performance (Non-controlled humidity mode)_________________________________ 8-4
How to Verify the Performance (Controlled humidity mode) ____________________________________ 8-5
How to Inspect the Electrical Compartment __________________________________________________ 8-6
How to Clean the Condenser______________________________________________________________ 8-6
How to Drain the Humidity System ________________________________________________________ 8-6
How to Verify the Temperature Calibration __________________________________________________ 8-7
How to Verify the Humidity Calibration ____________________________________________________ 8-7
Humidity Sensor Calibration and Maintenance _______________________________________________ 8-8
How to Verify the F4 Controller’s Input 2 (Humidity Input) Calibration____________________________ 8-8

Table of Contents
Theory of Operation______________________________________________________________8-9
Overview_____________________________________________________________________________ 8-9
Air Heating System_____________________________________________________________________ 8-9
Humidity System_______________________________________________________________________ 8-9
Refrigeration System (non-humidity mode) _________________________________________________ 8-10
Refrigeration System (controlled-humidity mode) ____________________________________________ 8-11
Troubleshooting ________________________________________________________________8-12
Refrigeration System Charging Instructions_________________________________________8-14
R-404A High-Stage Charge _____________________________________________________________ 8-14
R-508B Low-Stage Charge______________________________________________________________ 8-14
Recommended Spare Parts _______________________________________________________8-15
Major Electrical Parts ___________________________________________________________8-16
Major Refrigeration Parts________________________________________________________8-17
General Parts __________________________________________________________________8-17
Series F4 Controller Setup Parameters _____________________________________________8-18
Series F4 Setup Parameters______________________________________________________________ 8-19
Series F4 Operations Parameters__________________________________________________________ 8-20
Series F4 Set Lockout Parameters_________________________________________________________ 8-20
EZ-Zone Limit Controller Setup Parameters ________________________________________8-21
Setup Menu__________________________________________________________________________ 8-21
Operations Menu______________________________________________________________________ 8-21
Chapter 9 - Warranty________________________________________________________9-1
Chapter 10 – Drawings______________________________________________________10-1

Chapter 1 – Safety
TestEquity 123H Temperature/Humidity Chamber Page 1-1
Chapter 1 – Safety Instructions
Introduction
Follow all CAUTION notices to prevent damage to the chamber or your test sample. Failure to
follow all CAUTION notices may void your warranty. CAUTION may also indicate a
potentially hazardous situation which, if not avoided, may result in minor or moderate personal
injury.
WARNING indicates a potentially hazardous situation which, if not avoided, could result in
death or serious injury.
The safety alert symbol !precedes a general CAUTION or WARNING statement.
The electrical hazard symbol 2precedes an electric shock hazard CAUTION or WARNING
statement.
Installation Safety Notices
2WARNING: The power cord is equipped with a NEMA 5-20P grounded/polarized plug. To
prevent a shock hazard, DO NOT defeat the ground or polarization feature.
This device MUST be plugged DIRECTLY into a properly grounded and
polarized NEMA 5-20R receptacle. Due to high current demand on start-up,
use of an extension cord is NOT recommended.
!CAUTION: The minimum clearance you should allow for proper ventilation around the
chamber must be at least 6" from both the left and right side, and 12" from the
rear.
!CAUTION: This chamber is designed for operation in a conditioned laboratory
environment. Operation above 30°C (85°F) or below 16°C (60°F) ambient
room temperature is NOT recommended.

Chapter 1 – Safety
Page 1-2 TestEquity 123H Temperature/Humidity Chamber
Operation Safety Notices
!CAUTION: The “Series F4 User’s Manual” is a general manual and is written by the
manufacturer, Watlow, for a wide variety of applications and configurations.
Not all features or functions are applicable. Only the capabilities of a model
F4DH-CKCC-01, as described on page A.7 of the “Series F4 User’s Manual”
are applicable. “Cascade Control” as described on page 3.6 of the “Series F4
User’s Manual” is not applicable in this configuration. The “Retransmit”
function is available as an option.
!CAUTION: The Series F4 alarms are configured for internal protection of the humidity
system. Do NOT change this configuration under any circumstances. The
independent EZ-Zone Limit Controller functions as the main system and
product protection device.
!CAUTION: The Series F4 Controller has been properly configured by TestEquity to match
the chamber’s system requirements and to perform optimally over a wide
range of operating conditions. Improper modifications to these setup values
can result in erratic performance and unreliable operation. Setup examples in
the “Series F4 User’s Manual” are NOT applicable to this chamber. Do not
attempt to modify the setup values, unless you thoroughly understand what
you are doing. If there is any doubt, please call TestEquity before proceeding.
!CAUTION: NEVER select “Full Defaults” in the Series F4 Controller’s Factory/Test
Menu. This will erase all the correct values which are documented in the
“Series F4 Controller Setup Parameters” section of this manual.
!CAUTION: The EZ-Zone Limit Controller has been properly configured by TestEquity to
match the chamber’s system requirements. Improper modifications to these
setup values can result in unreliable and unsafe operation. Do not attempt to
modify the setup values, unless you thoroughly understand what you are
doing. The correct values are documented in the “EZ-Zone Limit Controller
Setup Parameters” section of this manual.
!CAUTION: Always verify that the Limit Controller’s high and low limits are set to
temperatures that are appropriate for your test sample.
!CAUTION: If your test sample is energized, it may be capable of raising the workspace
temperature beyond safe limits. This could occur if your test sample exceeds
the live load rating of the chamber or if the chamber’s refrigeration system
fails. This chamber has a set of contacts that can be used to remove power to
your test sample if the Limit Controller’s temperature limits are exceeded.
!CAUTION: To prevent damage to your test sample and the chamber’s compressors, do not
exceed the live load rating of the chamber.

Chapter 1 – Safety
TestEquity 123H Temperature/Humidity Chamber Page 1-3
!WARNING: Do NOT put items in the chamber that could burn or explode at high
temperatures. This chamber uses open wire heating elements which generate
surface temperatures over 1000ºF. This is NOT an explosion-proof chamber.
!WARNING: Do NOT put items in the chamber which can emit corrosive vapors or
substances.
!WARNING: This chamber is NOT a curing oven. There are NO provisions for venting
fumes.
!WARNING: The chamber door must remain closed while the chamber is operating. If you
need to open the door while the chamber is operating, wear safety goggles to
prevent the high velocity airflow from blowing particles or objects into your
eyes.
!WARNING: This chamber operates at extreme temperatures. Avoid contact with air,
objects, and surfaces that are hot or cold to prevent severe burns or frostbite.
Protective gloves are recommended.

Chapter 2 – Installation
TestEquity 123H Temperature/Humidity Chamber Page 2-1
Chapter 2 – Installation
Uncrating
Inspect the shipping container for any signs of visible damage. Notify the carrier and TestEquity
immediately if there are signs of shipping damage.
The pallet is designed with ramps so the chamber can be rolled off without the need for a forklift
or pallet jack.
1. Cut the two metal bands that hold the packaging to the pallet.
2. Remove the top cover.
3. Remove the plastic fasteners that hold the outer box together and remove the outer box.
4. Locate the retainer in the front of the pallet. Remove the two screws, then remove the
retainer. Keep in mind that there is also Velcro that holds the retainer in place. Place the
retainer in the front of the pallet on the floor.
5. Locate the two ramps under the chamber and remove them.
6. Attach the ramps to the front of the pallet using the Velcro straps. The retainer will be under
the ramps and act as a support.
7. Carefully roll the chamber off the pallet, onto the ramps. This should be done with at least
two people.
Preparation For Use
1. Inspect the chamber for signs of shipping damage.
2. Read this entire manual.
3. Select a suitable location to install the chamber.
4. Connect to the power source.
5. Perform following the procedures as described in the Preventive Maintenance section:
a. Inspect the electrical compartment.
b. Inspect the refrigeration machinery compartment.
e. Verify the chamber performance.

Chapter 2 – Installation
Page 2-2 TestEquity 123H Temperature/Humidity Chamber
Installation Location
The chamber will produce a significant amount of heat during normal operation. Locate the
chamber in a room with adequate ventilation to prevent excessive heat build-up. The chamber
generates a heat load of up to 5,000 btuh during a continuous cool down from a high
temperature.
The chamber must be on a solid and level floor. Allow enough space around the chamber to
permit serviceability and the removal of the service access panels, which are located on each side
and the rear.
!CAUTION: The minimum clearance you should allow for proper ventilation around the
chamber must be at least 6" from both the left and right side, and 12" from the
rear.
!CAUTION: This chamber is designed for operation in a conditioned laboratory
environment. Operation above 30°C (85°F) or below 16°C (60°F) ambient
room temperature is NOT recommended.

Chapter 2 – Installation
TestEquity 123H Temperature/Humidity Chamber Page 2-3
Humidity Water Connection
2CAUTION: The humidity system must be supplied with demineralized water having a
specific resistance of 50,000 to 200,000 ohms/centimeter. The use of
unfiltered tap water or triple-distilled water will damage the humidity system
and chamber interior, and will void the warranty.
Plumbed Demineralized Water Installation
Follow these instructions if your chamber is NOT being used with the optional water
recirculation system, and you are connecting to a plumbed source of demineralized water.
1. Attach a supply of demineralized water to the Water Supply fitting on the chamber. Water
pressure must not exceed 50 psi.
2. The chamber drain water is not under pressure, and is fed by gravity. Therefore, it must
empty into an open floor drain, condensate pump, or bucket.
Water Recirculation System Installation, Model W100
The optional Model W100 Water Recirculation System provides a source of demineralized water
for the humidity system, using ordinary tap or pre-filtered water. Condensate from the chamber
is returned back to the water tank. The water pump runs continuously when the humidity system
is enabled, keeping the supply line pressurized at all times. Detailed assembly pictures are shown
on the next page.
1. Attach filter cartridge. Use clamp provided on each end of filter to prevent leaking. Do not
overtighten.
2. Position the recirculation system on the back left side of the chamber.
3. Attach the chamber Water Supply hose from the chamber to the top fitting of the filter. Use
clamp provided to secure the hose to the Water Supply fitting.
4. Attach the chamber Drain hose to the chamber and position it so it goes into the water tank.
The drain hose must not be submerged in the water.
5. Fill the water tank with clean water.
6. Place the cover on the water tank.
7. Plug the pump power supply into the receptacle labeled Pump on the rear of the chamber.
Water Recirculation System Filter Cartridge Replacement
The demineralizer filter cartridge must be replaced when it is used up. The color of the top half
of the cartridge changes gradually through continued use. Replacement cartridges are available
from TestEquity (part number TE-0014 for a carton of 6 cartridges).
The demineralizer filter cartridge will last longer if pre-filtered water is used, although this is not
a requirement. Rather than filling the recirculation system reservoir with tap water, you can use
filtered drinking water (not spring water) or distilled water (supermarket quality, but not triple
distilled lab quality).

Chapter 2 – Installation
Page 2-4 TestEquity 123H Temperature/Humidity Chamber
Water Recirculation System Assembly, Model W100
Finger-tighten the Water Supply and Drain connections to chamber. Plug the pump power supply into receptacle
on the back of the chamber. The drain tube from the chamber must
not be submerged in the water.
Bottom of Filter Top of Filter
Clamp
Clamp
Reservoir drain. Drain water
when it appears dirty.
Replace filter when white portion
turns brown up to this point.
Clamp
NOTE: The rear panel
of your chamber may
look different.

Chapter 3 – Operation
TestEquity 123H Temperature/Humidity Chamber Page 3-1
Chapter 3 – Operation
Introduction
The Front Panel Switches control power to the chamber. The Front Panel Lights provide
indication of heat and cool functions.
The EZ-Zone Limit Controller is a protection device. It turns the chamber OFF if the workspace
temperature exceeds either a high temperature or low temperature limit set point.
The F4 Controller controls the temperature and humidity of the chamber. It can function as either
a single set point controller or as a programmable profile controller. The F4 Controller
automatically turns the refrigeration system on or off based on the demand for cooling.
Summary of Chamber Operation
1. Turn the Power Switch ON.
2. Enter the appropriate high and low temperature safety limits on the Limit Controller.
3. Enter the desired set points (or program) on the F4 Controller.
4. Load your test sample in the chamber.
5. If you are running a controlled humidity condition between +10°C and +85°C, turn Event 2
ON.
6. If you are running temperature conditions lower than +10°C or greater than +85°C, turn
Event 2 OFF. Humidity cannot be controlled in this mode.
7. Turn the Conditioning Switch ON.

Chapter 3 – Operation
Page 3-2 TestEquity 123H Temperature/Humidity Chamber
Front Panel Switches and Lights
Power Switch
The Power Switch controls power to the entire chamber. The Power Switch illuminates when it
is ON.
Conditioning Switch – ON Mode
The Conditioning Switch enables all chamber functions. When the Conditioning Switch is OFF
and the Power switch is ON, only the F4 Controller and Limit Controller are operational. When
both the Power and Conditioning Switches are ON, the chamber’s conditioning system will
function to maintain the temperature/humidity set point. The Conditioning Switch does not
illuminate.
Conditioning Switch – Event 1 Mode
When the Conditioning Switch is in the Event 1 position, you can enable and disable all chamber
functions through Event 1 (Digital Output 1) of the F4 Controller. When the Conditioning
Switch is in the Event 1 position and Event 1 on the F4 Controller is Off, all chamber functions
are disabled. If Event 1 is On, all chamber functions are enabled.
See page 4-7 for instructions on how to control the events in manual mode. In profile mode,
Event 1 is named CONDITION.
!CAUTION: Remember to set DigitalOut 1 (Event Output1) to On in static set
point mode when the chamber is to be operational. In this mode, the Modbus
register for Digital Output 1 is 2000.
!CAUTION: Remember to set CONDITION to On in the profile event prompt for all
programmed steps when the chamber is to be operational.
Light Switch
The Light Switch controls the workspace light. The Light Switch illuminates when it is ON.
Heat Light
The Heat Light will illuminate when the F4 Controller turns on the heater to maintain the
workspace temperature. The Heat Light will cycle on/off as the workspace temperature
approaches and reaches the temperature set point. This light corresponds to the 1A indicator on
the F4 Controller.
Cool Light
The Cool Light will illuminate when the F4 Controller turns on the cooling valve to maintain the
workspace temperature. The Cool Light will cycle on/off as the workspace temperature
approaches and reaches the temperature set point. This light corresponds to the 1B indicator on
the F4 Controller.

Chapter 3 – Operation
TestEquity 123H Temperature/Humidity Chamber Page 3-3
Humidity Enable Light
The Humidity mode is enabled through Event 2 (Digital Output 2) in the F4 Controller. Event 2
should ONLY be ON if you are performing a controlled humidity test within the humidity range
of the chamber (+10°C and +85°C).
If Event 2 is OFF, the Humidity mode is disabled. The chamber will cool in cascade mode (both
compressors running).
If Event 2 is ON, the Humidity mode is enabled and the Humidity Enable light will be
illuminated, as long as the chamber temperature is within +7°C and +90°C. The chamber will
cool in single-stage mode (one compressor running).
Humidity Light
The Humidity Light will illuminate when the F4 Controller turns on the humidifier heater to
maintain the workspace humidity. The Humidity Light will cycle on/off as the workspace
humidity approaches and reaches the humidity set point. This light corresponds to the 2A
indicator on the F4 Controller.
Note that the Humidity Enable Event 2 must be ON, the chamber workspace must be between
+7°C and +90°C, and the humidifier water level must be correct for the Humidity Light to
correspond to the 2A indicator on the F4 Controller.
The 2B indicator on the F4 Controller lights when dehumidification is required to maintain the
workspace humidity. There is no corresponding pilot light on the front panel for this function.

Chapter 3 – Operation
Page 3-4 TestEquity 123H Temperature/Humidity Chamber
Loading the Chamber
!WARNING: Do NOT put items in the chamber that could burn or explode at high
temperatures. This chamber uses open wire heating elements which generate
surface temperatures over 1000ºF. This is NOT an explosion-proof chamber.
!WARNING: Do NOT put items in the chamber which can emit corrosive vapors or
substances.
!WARNING: This chamber is NOT a curing oven. There are NO provisions for venting
fumes.
!WARNING: The chamber door must remain closed while the chamber is operating. If you
need to open the door while the chamber is operating, wear safety goggles to
prevent the high velocity airflow from blowing particles or objects into your
eyes.
!WARNING: This chamber operates at extreme temperatures. Avoid contact with air,
objects, and surfaces that are hot or cold to prevent severe burns or frostbite.
Protective gloves are recommended.
!CAUTION: If your test sample is energized, it may be capable of raising the workspace
temperature beyond safe limits. This could occur if your test sample exceeds
the live load rating of the chamber or if the chamber’s refrigeration system
fails. This chamber has a set of contacts that can be used to remove power to
your test sample if the Limit Controller’s temperature limits are exceeded.
!CAUTION: To prevent damage to your test sample and the chamber’s compressors, do not
exceed the live load rating of the chamber.
Live Load Capacity for Model 123H
Temp +23°C 0°C –40°C –55°C –65°C
Watts 500 W 400 W 225 W 175 W 100 W
Performance Considerations
The performance of all chambers is significantly affected by the characteristics of your test
sample. Factors include size, weight, material, shape, and power dissipation if energized.
The test sample should be placed in the chamber in a manner that allows for air circulation. The
air plenum is located on the back wall of the chamber, where air is sucked in from the bottom
and exits from the top. You should not place the test sample directly on the chamber floor. It
should be placed on the shelf. Multiple test samples should be distributed throughout the
chamber to ensure even airflow and minimize temperature gradients. If necessary, additional
shelves should be used to evenly distribute the load. Verify that the temperature gradients are
within acceptable limits, by measuring the chamber temperature at strategic points using a
multipoint thermocouple meter or data logger.
You may find that the temperature throughout the chamber is even, but always different from
what the F4 Controller indicates. The correct way to adjust what the F4 Controller “displays”

Chapter 3 – Operation
TestEquity 123H Temperature/Humidity Chamber Page 3-5
compared to what is measured at some point other than the controller’s sensor is with the
“Calibration Offset” parameter, NOT by recalibrating the controller.
Port Plugs
Foam port plugs are provided with a gray silicone surface on one side. The port plug must be
inserted with the gray silicone surface facing the inside of the chamber. Port plugs should be
considered expendable and be replaced when they no longer provide a good seal.
Avoiding Moisture (non-humidity mode)
Any time the ambient air is subjected to temperatures below the dew point, moisture will
condense out of the air. The effect is ice or frost during low temperature operation, or water
when maintaining over 0°C and cooling is required.
To avoid moisture condensation, make sure the port plugs are inserted at all times. Also, avoid
opening the chamber door while the chamber is operating at temperatures below room ambient.
When a low temperature test is completed, warm the chamber to at least room ambient before
opening the chamber door and before removing your test sample.
You CANNOT use the humidity system to control moisture at low temperatures. The humidity
system is disabled below +7°C. However, if you have a source of GN2(gaseous nitrogen) or Dry
Air, you can use the Purge system to eliminate moisture condensation at low temperatures.
Internal Test Fixtures
Some applications require internal fixtures to support test samples and provide a convenient
method of connecting wires and sensors. Fixtures must be designed to minimize their impact on
chamber functionality and performance.
Fixtures should be designed for easy removal to permit maintenance and cleaning of the
chamber. The chamber liner should never be drilled or screwed into. This will compromise the
integrity of the liner and permit moisture migration due to condensation into the insulation,
which will eventually impact performance and lead to premature rusting of the outer cabinet.
Fixtures should be constructed of stainless steel. This also applies to all screws and fasteners. All
welds should be passivated. To prevent rust and corrosion, never use iron or mild steel even if it
is painted or plated. Aluminum may be used. However, since the specific heat of aluminum is
double that of steel, it represents a greater load and will have more impact on the chamber
performance.
Make sure that all connectors, wiring, pc boards, and auxiliary components can withstand the
temperature extremes that they will be subjected to. In some cases, these components may not be
able to last after repeated tests and should be considered expendable.