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HM-436 Environmental Testing Chamber
 Environmental Testing Chamber



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The Model HM-436 is a steady-state temperature and humidity test chamber specially designed for hydrogen-maser atomic clocks. 

With 34.6 cubic feet of workspace, the HM-436 is designed to generate and control temperature and humidity environments at and above +23°C (+73.4°F) at 35% relative humidity.

The test chamber is designed for minimal maintenance. Run long-term tests at a constant, steady-state temperature and humidity, or cycle testing with well-tuned reliability. It is known for its ability to run unparalleled tight temperature and humidity control.

HM test chambers feature heating systems equipped with open ceramic-core nichrome heaters for reliable and accurate temperature control within ±0.5°C (±1.0°F).

The humidity system is tuned to operate at a constant 35% relative humidity. For humidification, a vapor generator system incorporating stainless steel blower wheels is used to introduce water vapor into the chamber. The system utilizes safeties to de-energize the vapor generator in the event of no water to the generator tank. Dehumidification is accomplished with a mechanical refrigeration system.

The cooling system consists of a self-contained, compact, mechanical, single-stage refrigeration system. 

The HM-436 has casters to increase mobility and offer flexibility in your laboratory. Two doors, front and back, open fully into the workspace and includes a removable ramp.  Two power outlets are housed inside the workspace. A 3-inch port on the right side is centered in the workspace from top-to-bottom and front-to-back.  

The standard instrumentation includes two manual-set digital controllers for independent control of the temperature and humidity.

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  • Specifications
  • Standard Features
  • Instrumentation
  • Safety Features


Interior: 33.0W x 37.0D x 49.0H (in)
  838.2W x 939.8D x 1244.6H (mm)
Exterior: 48.0W x 50.0D x 81.0H (in)
  1219.2W x 1270D x 2057.4H (mm)
Volume: 34.62 cubic ft
  980.32 liters
Temperature: 23°C to °C (73.4°F to 77°F)
Humidity: 35% RH steady state with load
Humidity Fluctuation: ±5% RH at sensor
Electrical Supply:  208 VAC, 1 PH, 50HZ or 60HZ
Full Load Amps: 12 A
Power Requirement: NEMA L6-20
Refrigeration System:  Single stage
Mobility: Will fit through 62 in doorway
Approximate Product Weight: 1380.0 lbs (626 kg) without added options
Approximate Shipping Weight: 1490.0 lbs (676 kg) without added options

Standard Features


  • Internal light with external switch
  • Forced air circulation
  • Standard full opening door, right-hand hinge
  • Two 115v, 15a interior outlets
  • Full-height battery access door
  • Self-contained refrigeration system
  • Mechanical dehumidification system
  • Steam generator humidity system
  • Floor supports 600 lbs
  • Live load supported up to 75-100 watts
  • Locking swivel casters, set of 4




2 Independently controlled, manual-set Watlow EZ-ZONE PM controllers for temperature and humidity control (non-programmable)


HM Series Test Chambers can incorporate AESONE CONNECT creating a robust connected device for a standard and uniform interface making test chamber operation easier.

AESONE XCHANGE increases your functionality    AESONE CONNECT allows for secure remote access to your test chamber and gives easy profile creation, operational control, and data management.

  • Connects the test chamber controller to your network for increased accessibility
  • On-board multi-year data logging

AESONE SOFTWARE gives you the power to

  • Remote chamber operation and monitoring, 
  • Web-based test profile creation, 
  • Viewing current data and historical data visually
  • Secure multi-level user access 

WATLOW F4T PROGRAMMABLE CONTROLLER. Features a 4.3” capacitive touchscreen minimizing the chance for error. Ethernet communication supported by AESONE HARDWARE. View more controller options



for temperature, 100 OHM platinum RTD is highly-accurate sensor made from platinum components for increased sensitivity
for humidity, solid-state sensor for 10-95% relative humidity
View sensor options


OPTIONAL DATA LOGGERS. View additional data loggers

Safety Features


  • Internal high-temperature limit safety
  • Refrigeration system over-pressure safety circuit
  • Low-water steam generator over-temperature circuit