What it is

The Espec Criterion series is a line of compact benchtop temperature and temperature-humidity chambers built for fast cycling in a narrow footprint. The chambers reach extended ranges, as cold as −70 °C and up to +180 °C, and cycle at rates up to 5 °C/min without liquid nitrogen, so a bench-sized unit can run the kind of extreme, high-rate testing that usually requires a larger floor-standing chamber. Two interior sizes (1.5 cu ft and 4 cu ft) share the same 30.25 in × 33.5 in exterior footprint, and every model uses the Watlow F4T touch-screen controller with an Ethernet interface. The 4 cu ft BTL-433 and BTX-475 add 10 to 95% RH humidity control.

• Two interior sizes: 1.5 cu ft (42 L) and 4 cu ft (110 L)
• Temperature range −70 to +180 °C (−20 to +180 °C on the −x33 models)
• Temperature change rates up to 5 °C/min without liquid nitrogen
• Humidity 10 to 95% RH on the 4 cu ft BTL-433 and BTX-475
• Temperature fluctuation ±0.5 °C; gradient ±1.5 °C (per IEC 60068)
• Watlow F4T touch-screen controller; up to 40 profiles; Ethernet and Modbus
• Narrow footprint (30.25 in × 33.5 in), vents out the top, installs against a wall
• Stainless-steel interior and exterior; one 2 in cable port standard
• One-year parts and on-site labor warranty
• Runs on 115 V or 208/230 V single-phase, 60 Hz (50 Hz export version available)

Model lineup

BTZ-175E is the 50 Hz (230 V) version of the BTZ-175; performance is otherwise identical.

What it is used for

The Criterion chambers bring extended-range, fast-cycling testing to a benchtop:

• Temperature cycling and thermal stress — high-rate cycles up to 5 °C/min to accelerate testing and add thermal stress to samples
• Extreme-range testing — hot and cold testing to −70 °C and +180 °C without a floor-standing chamber
• Temperature-humidity testing — combined temperature and humidity work on the 4 cu ft BTL-433 and BTX-475 at 10 to 95% RH
• Reliability and QA in tight labs — a variety of temperature and humidity testing where floor space is limited
• Powered-specimen testing — operating powered equipment inside the chamber through the interlocked specimen-power terminal

Key features

Space-saving, wall-adjacent install. A 19.5 in wide interior, 3.5 in wider than traditional benchtops, in an exterior 20% narrower. The refrigeration vents out the top and utilities connect on the sides, so the chamber can sit against a wall.

Fast changes without liquid nitrogen. Cycling up to 5 °C/min on the BTZ-175 saves significant test time and adds thermal stress; performance is stated per IEC 60068-3-5 at the supply air.

Extended cold without LN2. The BTZ and BTX models reach −70 °C without liquid nitrogen; the BTU and BTL models cover −20 °C. An optional LN2 injection boost is available for still-faster cooling.

Humidity expertise on the 4 cu ft models. BTL-433 and BTX-475 control 10 to 95% RH, with an optional extended low-humidity range to 5 °C / 15% RH.

Three-level overheat protection. A programmer setpoint, an independent settable monitor, and a thermal fuse, plus an interlocked specimen-power terminal that shuts down the powered device if the chamber stops.

Quality cabinet. Stainless-steel interior and exterior, rounded corners, a full thermal break around the door and doorframe, dual-layer fiberglass-and-foam insulation, a 2 in (50 mm) cable port on the left with a silicone plug, and a floor drain with drip tray.

Watlow F4T controller

The Watlow F4T is a touch-screen programmer and controller that stores up to 40 test profiles, with ramp, soak, jump/repeat, auto-start, and end step types. It includes an Ethernet interface with Modbus protocol and one event relay with an external output terminal for activating other equipment during a test. Optional software adds full remote management and datalogging.

Why engineers pick it

Floor-standing performance on a bench. −70 °C, +180 °C, and up to 5 °C/min cycling without liquid nitrogen, in a chamber that fits on a benchtop.

The narrowest practical footprint. The same 30.25 in × 33.5 in exterior for both sizes, venting out the top and connecting on the sides, so it installs against a wall and frees lab space.

Humidity where it counts. The 4 cu ft BTL-433 and BTX-475 add reliable 10 to 95% RH control, with an optional low-humidity range to 15% RH.

Modern, connected control. The Watlow F4T touch screen, 40 stored profiles, and Ethernet and Modbus fit automated and remote workflows.

Backed by Espec. A one-year parts and on-site labor warranty, on a platform re-engineered for reliable, low-maintenance operation.

Choosing a model and ordering

Choose the low-temperature capability (−20 °C on the BTU and BTL, −70 °C on the BTZ and BTX), the size (1.5 cu ft or 4 cu ft), and whether you need humidity (the 4 cu ft BTL-433 and BTX-475). Options include a roll-around cart, 2 in / 4 in / 6 in cable ports, adjustable stainless-steel shelving, a heated viewing window with interior light, LN2 injection boost, an emergency-stop button, lithium-ion battery test safety features, extended low-humidity range, external or recirculating water supply, DI water filtering, and a Web Controller or paperless and chart recorders.

If you need faster ramping in the same interior. The Espec BTZ-4200 is built on this Criterion platform and shares the 4 cu ft interior dimensions exactly, but reaches 15 °C/min heat-up and cool-down against the 2.75 °C/min of the BTZ-475 and BTX-475, using cascade 3 hp scroll refrigeration and electrical utilities only.

Full per-model specifications are in the Specifications tab. Select your model and options on this page. For humidity configuration, LN2 boost, lithium-ion test safety, or a specific IEC 60068 cycle, contact W5 Engineering and we will configure and quote it with you.