Extremely Low Gradients with more usable workspace
Sigma Systems uses only powerful centrifugal blowers moving a counter-flow
air mass through a mixing plenum to provide a very homogenous air mixture
delivered evenly over the top of, and then down through, the workspace.
Heaters, coolant injection, and mechanical refrigeration evaporators are
placed before the blowers to further enhance the mixing process. The Sigma
plenum based air movement pattern is far superior to the top driven
vane-axial air movement systems found in most other chambers. Vane-axial
designs move air in a conical pattern from the top center of the chamber and
must rely on the workspace for mixing. Sigma's design sends an already
homogenous mixture of air from the top of the mixing plenum evenly over the
entire workspace. Your loads can use far more of the workspace you pay for
and have lower gradients at the same time. You may actually save money with
a Sigma Systems temperature chamber because you may be able to purchase a
chamber with a smaller workspace to do the same job. This is especially true
for bulky and/or gradient sensitive applications.
Control Flexibility & Accuracy
All Sigma Systems temperature chambers are provided with the Model C analog
controller unless the upgrade option for the Model C-4 programmable
controller is specified at time of purchase.
The Model C controller is the essence of reliable simplicity. Simply set the
temperature and turn it on.
The Model C-4 includes digital readout with .1 degree resolution, a full
tactile keypad, multi program programmability with up to 100 program steps,
remote control via RS-232 or IEEE-488, temperature averaging from two
inputs, °F and °C modes, and more.
All Sigma controllers (except the Model C) have provision for staged heating and lead
proportional lag damping (PID) control based on input from 500 ohm Pt RTDs
for the most accurate temperature control with minimal overshot. Internal
control resolution is better then .05°C with operating stability within .1°C
and .7°C accuracy. These controllers are immune to voltage fluctuations of
up to 20% of rated line voltage. Opto isolation and zero crossing switching
is used to reduce noise.
Click here to learn more about Sigma Systems controllers
Serious Warranty
Every Sigma Systems temperature chamber is warranted for life for
workmanship. Components and materials are warranted for one year. Warranty
service is fast, customer oriented, and arguments are few. The warranty
period for known problematic components is always extended until a suitable
alternative is available. It is the policy of the company to build the best.
We expect you to expect no less of us. We maintain our credibility and
reputation by treating you like you bought the best.
Quality Construction
Every Sigma Systems temperature chamber is carefully hand built by
experienced craftsmen using only the best available materials to execute our
carefully engineered designs. Shortcuts are never taken, details are always
a concern. These are just some examples of the quality that is integral to
every Sigma chamber:
- Stainless steel interiors for easy cleaning and corrosion resistance.
- Exterior cabinets made of spot welded cold rolled steel with TIG welded and
ground corners for strength and quality appearance.
- Extra tough epoxy powder coated exteriors for easy cleaning and exceptional
heat and abrasion tolerance.
- Low k factor, high heat tolerant, insulation for greater efficiency and long
service life.
- Double gasketed doors equipped with compression latches.
- Custom made stainless steel lift-off hinges on doors.
- Custom made blower motors utilizing stainless steel shafts, special extreme
temperature seals and lubrication, and thermal protection circuit.
- Composite face frames on working cavity for extreme temperature and long
test units.
- Custom made solenoid valves with specially sealed coils and valve/seat
assemblies designed for long life in extreme conditions.
Staged Heating
Sigma chambers have staged heating for extremely fast ramp rates and precise
control near the set point.
Failsafe
All Sigma ovens are supplied with an adjustable independent bi-metallic
overtemp power lockout system. This provide highly reliable protection
against overtemp conditions. Additional precision failsafe systems are
available to protect against both high and low out-of-range conditions.
Coolant
Either L-CO
2
or L-N
2
will permit very rapid temperature down ramps and
virtually unlimited live load dissipation. Also see Sigma literature on
mechanically refrigerated chambers for information on models using
mechanical refrigeration with expendable gas boost.
Chamber Options
All chambers equipped for expendable gas cooling are provided with a
standard 1½" exhaust aperture to prevent pressure build-up within the
chamber. Additional apertures are available as options.
Conversion kits are available to convert any sigma chamber from one type of
coolant to another. Also, more than one valve and injector can be provided
for coolant versatility.
Chamber Options
Special Sizes and Extended Temperature ranges
Rack Mount (smaller chambers only)
Castered stand (included with certain chambers)
Special sizes and extended temperature ranges
Door Window
Interior light(s)
Door feed-thrus (applicable to drawer type doors)
Door hinged on right side (left is standard)
Extra apertures (1¼" to 4")
Shelf standards and shelves
Air Cooling
Boost Coolant Solenoid & Injectors(s)
Dry nitrogen purge system
Coolant filter kit
Coolant conversion kit L-N2
<-> L-CO2
Extra coolant solenoid and injector(s)
Precision Hi-Lo failsafe – screwdriver adjustable or digital switch
Redundant low temp liquid nitrogen cut-off valve
Chart recorder (built in space permitting)
Secondary surface mount probe (with C4 controller only) for direct
product temperature sensing
Special Voltage Wiring
One or two programmed external device controls (contactor or solid state relay)
Resistance programmability (2 ohms/° C., model C controller only)
Voltage programmability (5mv./° C., model C controller only)
IEEE-488 or RS-232 computer bus programmability (included with C4 controller)
Programmed Compressor Control (Solid State relay) Allows On/Off control of the
compressor via a remote computer or the C4 controller
Single Zone Thermal Shock Chambers
Sigma Systems shock chambers were designed to provide an effective and
powerful single zone testing alternative to cumbersome and bulky two zone,
or shuttle type, shock testing devices. Capable of cycling between –65C and
+125C in less than 5 minutes with a 10 lb. passive aluminum load, Sigma
Systems single zone thermal shock chambers are extremely high performance
temperature chambers that meet the requirements of MIL SPEC 202, Method 107.
They feature extremely rapid cycling rates, extremely low gradients,
flexible programming capabilities, and rugged construction. Extended
temperature ranges are available. The chambers are cooled by L-N
2
.As with
all Sigma chambers and platforms, custom chamber models are available to
meet your specific needs.
Controlled by the Model C4 Controller, Sigma’s thermal shock chambers
provide a dynamic range of programming and remote control options.
