Lighting Science: The science behind ceramic metal halide

The science behind ceramic metal halide

Science behind ceramic metal halide CMH lamps recently taken hydroponic industry stormCeramic metal halide (CMH) lamps have recently taken the hydroponic industry by storm. First sold to the commercial/industrial market in 1994, CMH is a relatively new technology, especially when compared to HPS which has been available for over fifty years.

Good CMH lamps are more difficult to design and manufacture then HPS or quartz metal halide lamps. That being said, the juice is definitely worth the squeeze, as CMH has many features that set it apart from other light source technologies:

  • Higher efficacy: More µmol per watt. 315W CMH lamps boast 1.9 or higher µmol/W
  • Fuller spectrum: CMH lamps typically have over 3X the color rendering of HPS lamps. They provide more natural representations of violet, blue, orange, red.
  • Longer life: 20,000 to 25,000 hours of rated life (where 50% of lamps fail) is fairly common.

What’s the ‘special sauce’ behind the technology?

CMH lamps have a ceramic arc tube (the small bulb within the lamp) rather than quartz arc tube used in traditional metal halide lamps. Ceramic arc tubes can operate at higher temperatures (over 1700 degrees Fahrenheit). The ceramic tube is filled with mercury, argon and metal-halide salts (for example, sodium or scandium iodides). Because of the higher wall temperature, the salts are vaporized into metallic atoms and iodine which help to broaden the spectrum to a much higher degree when compared to HPS. In addition, the higher arc tube temperature drives higher efficacy (µmol/Watt)

Sunmaster has recently launched new 315W CMH lamps, dosed with proprietary halides to enhance key areas of the spectrum. Sunmaster is currently developing higher wattage CMH lamps for 2018 launch.

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