The Criterion temperature/humidity chamber series provides an economical and space-saving solution for a variety of testing requirements. The chamber's interior size is 3.5 inches wider than traditional benchtops, yet the exterior is 20% narrower. Some models use 115V power, meaning no special power hook-ups.

  • Lowest temperature: -20 or -70°C (-4 or -94°F)
  • Highest temperature: 180°C (354°F)
  • Humidity range: 10 to 95% RH
  • Chamber size: 1.5 or 4 cubic feet
  • Touch-screen Watlow F4T programmer with Ethernet access

The four cubic foot workspace is the largest to be found in a benchtop unit, while requiring less footprint than even smaller comparable chambers. The vertical configuration saves bench space, plus the refrigeration’s ventilation design allows installation against a wall for even more space savings.

The programmer includes a temperature alarm as just one part of ESPEC's three-tiered over-temperature protection system. A thermal fuse and a user-set independent limit are also included. In addition, a specimen power terminal allows the user to safely operate powered equipment inside or with the chamber.

ESPEC Expertise in Humidity Control

Controlling humidity in a small environmental chamber can be especially challenging. ESPEC expertise in humidity control brings intelligent design that is carefully integrated into the Criterion chambers. The humidity subsystems are designed for reliability, convenience, and performance:

  • The steam generator allows expanded humidity range and is easy to maintain.
  • A separate de-humidification coil improves low humidity control and range.
  • Wet-bulb humidity sensor is a “primary measurement method” for accuracy. It is also economical, easy to maintain, and reliable because it has no risk of failure due to over-saturation. (Read why analog is preferred over digital.)
  • Direct water supply connection is standard, with options for water filtering and recirculating water tank.
Features for Criterion Benchtop Chambers
  • High performance and quiet operation (65 dBa)
  • Space-saving footprint, designed for flush installation to wall
  • Stainless steel exterior
  • Full thermal break around doorframe
  • One 50mm (2”) diameter cable port on left, with flexible silicone plug
  • Three levels of overheat protection, plus overcool protection
  • Easy lift-off service panels, electrical access on left
  • Detachable eight-foot power cord with plug
  • Humidity models include direct water supply connection for continuous operation (supply tank optional)
  • ETL listed electrical panel conforming to UL 508A

Touch-screen programmer/controller with Ethernet

  • Watlow F4T with touch-screen and Ethernet port standard
  • Save 40 profiles with up to 50 steps each (ramp, soak, jump, auto-start, end)
  • One event relay for external device control, plus specimen power interlock relay for safety
  • ESPEC exclusive options include: Web Controller for full remote access; Chamber Connect software for basic data logging and monitoring. USB and RS-485 ports available, as well.

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Temperature & temperature/humidity models

Product Suggestions
    Model NumberInterior Dimensions
    (W x D x H)
    Interior VolumeTemperature RangeHumidity ControlChange Rate
    BTU-13319.6" x 11" x 12"1.5 cu. ft.-20 to 180°CNo up to 2°C/min.
    BTU-43319.6" x 15" x 23.6"4 cu. ft.-20 to 180°CNo up to 1.5°C/min.
    BTL-43319.6" x 15" x 23.6"4 cu. ft.-20 to 180°CYes up to 1.5°C/min.
    BTZ-13319.6" x 11" x 12"1.5 cu. ft.-70 to 180°CNo up to 3.5°C/min.
    BTZ-17519.6" x 11" x 12"1.5 cu. ft.-70 to 180°CNo up to 5°C/min.
    BTZ-175E19.6" x 11" x 12"1.5 cu. ft.-70 to 180°CNo up to 5°C/min.230V 50Hz export model
    BTZ-47519.6" x 15" x 23.6"4 cu. ft.-70 to 180°CNo up to 2.75°C/min.Quick Ship
    BTZ-475E19.6" x 15" x 23.6"4 cu. ft.-70 to 180°CNo up to 2.75°C/min.230V 50Hz export modelQuick Ship
    BTX-47519.6" x 15" x 23.6"4 cu. ft.-70 to 180°CYes up to 2.75°C/min.

          Click model number for details, including metric & english units.

    The F4T is the newest programmer/controller from Watlow, with a touch-screen and Ethernet interface. ESPEC offers optional software for remote management and datalogging. 

    Touch-screen programmer/controller with Ethernet

    • One event relay for external device control, plus specimen power interlock relay for safety
    • ESPEC exclusive options include: Web Controller for full remote access; Chamber Connect software for basic data logging and monitoring
    • USB memory and RS-232/485 ports available as options
    • Save 40 profiles with up to 50 steps each

    F4T Specification: (ESPEC Configuration)


    Color touch-screen, 4.3 inches
    Quickly and easily identify process, alarm, and setpoint values

    Control Method

    PID (Proportional, Integral, Derivative)


    Standard: Ethernet with MODBUS & SCPI
    Optional: RS-232/485, Web Controller
    Only one interface type may be installed

    Operating Modes

    STOP: chamber off, programmer on
    PROGRAM: Runs selected test profile
    CONSTANT: runs at set value continually

    Program Capacity

    40 profiles, 50 steps per program

    Programming Capabilities

    Ramp and soak functions
    Profiles can be programmed to wait for events or up to three process variables
    Soak control delays timer until setpoint is reached

    Additional Functions

    High/low limit alarm functions
    Digital inputs can be programmed remotely, start, pause, terminate profiles
    A real-time clock can be used to start a profile at any time
    Controller is UL/CUL & CE listed

    Constant Mode

    Used for quickly setting a single operating condition. Chamber will continue to run this condition until stopped. Program and other settings may be entered while the system is running.

    Software Options

    Learn more about ways to access ESPEC controllers via software our support page:
    Software for Watlow F4T

    Recommended: Web Controller

    The ESPEC Web Controller is an embedded server/software solution for monitoring and programming your chamber via Ethernet. Works with P-300, SCP-220, F4T, & F4 controllers.

    See the brochure
    Self-install kit for existing units
    Try the live demo now!

    Independent of the controller itself, the Web Controller adds additional capabilities for datalogging, programming, alarm emails, and RESTful API.

    Product Suggestions

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