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HM-436 Environmental Testing Chamber
HM-436 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: 33W x 37D x 49H (in)
  838.2W x 939.8D x 1244.6H (mm)
Exterior: 48W x 50D x 81H (in)
  1219.2W x 1270D x 2057.4H (mm)
Volume: 34.62 cubic ft
  980.42 liters
Temperature: 23°C to 23°C (77°F to 77°F)
Humidity: 35% RH steady state with load
Humidity Fluctuation: +/-5% RH at sensor
Electrical Supply:  208VAC or 230VAC, 1PH, 50HZ or 60HZ,
Full Load Amps: 12A
Power Requirement: NEMA L6-20
Mobility: Will fit through 62" door


  • 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 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 functionalityaesone-connect

  • 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