Criterion Temperature & Humidity Benchtop Chambers

Our largest benchtop humidity chamber


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. The BTL-433 model uses 115V power, meaning no special power hook-ups.

  • Lowest temperature: -20 or -70°C (-4 or -100°F)
  • Highest temperature: 180°C (354°F)
  • Humidity range: 10 to 95% RH
  • Chamber size: 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:

  • An external steam generator allows expanded 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.

  Compare Benchtop Models Side-by-side comparison of up to three models.


  • 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
  • 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.

Criterion Temperature & Humidity Benchtop Model Comparison

Clear Filters

Model / Link Interior Dimensions
(W x D x H)
Interior Volume Temperature Range Humidity Control Change Rate
BTL-433 19.6" x 15" x 23.6" 4 cu. ft. -20 to 180°C Yes up to 1.5°C/min.

Quick Ship

BTX-475 19.6" x 15" x 23.6" 4 cu. ft. -70 to 180°C Yes up to 2.75°C/min.
Click model number for details, including metric & english units.

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