Far-infrared Heater

Quartz Tube Heater FHR Type

The quartz tube heater FHR uses a Kanthal alloy wire as the heating element, it is placed in a transparent quartz tube after flower winding.

The temperature rise of the heater is slow compared to halogen heaters, and radiation power per unit length is less than half, as the radiation wavelength band is far infrared, it is often more suitable for heating paper, cloth, paint, plastics etc. to about 572ºF (300°C) to 752ºF (400ºC) than halogen heaters.

Quartz tube is the ideal material for radiating elements in the far infrared region. Emissivity of quartz glass is close to zero up to a wavelength of approximately 3 µm, and exceeds 95% for wavelengths of 3 to 4 µm or more. In other words, it is an ideal far-infrared radiation material that selectively radiates only far infrared rays.

Quartz glass is transparent at 3 µm or less, direct radiation from the heating wire passes through. However, the energy ratio is less. The heating wire looks red hot and gives a positive visual indication (safe and warm feeling as the energized state can be visually confirmed).

Compared to ceramic material that emits far infrared, quartz has superior radiation characteristics, is completely harmless, does not crack or electric leakage even when it is wet, and can be used with confidence for applications where safety is required and for heating foodstuffs.

FHR type is a far-infrared heater.

To use infrared heating, the following infrared properties should considered and select either far-infrared heater or near-infrared heater.

When far-infrared heater is used to heat adhesives, the surface will be burnt. When near-infrared heaters are used, it permeates and heats internally and internal bubbles are generated. Often it is misunderstood that “Far-infrared rays heat by penetrating internally” because of wrong advertisement by vendors and is completely incorrect. Besides this, there are many misunderstandings of far-infrared heating.

For detailed explanation about these, refer to the page “Physics of light heating”

When you heat printed paper with far-infrared heater, it is heated as a whole. When heated with near-infrared heater, the printed letters are heated strongly while the blank portion is not heated much. That is, with near-infrared heater, there is a difference in the tendency for the ease of absorption depending on the surface condition (color etc.) of the object to be heated.

When meat is heated with a near-infrared heater, the areas where burning starts becomes black, the black areas absorb near infrared better heating the same areas intensively heated which then gets scorched. That is, heating is uneven. Far infrared heaters heats evenly.

Normally, near-infrared heaters can be used in about 1 second after the power has been turned ON, while far-infrared heater requires 30 seconds to several minutes.

Conversion efficiency of supply power to infrared by near-infrared heaters is good at 80 to 90%. The conversion efficiency for far-infrared heaters is 60 to 70%. Energy that was not converted to infrared is mainly used to heat up the air.

The density of energy radiated from the heating element of the heater is high for near-infrared heaters and low for far-infrared heaters.

The difference is 20 to 40 times. Even if collector mirror collects infrared rays at one point, it will not exceed the surface density of the heating element due to which far-infrared heaters cannot give a very high energy density. Rapid heating and high temperature heating is not possible with far infrared rays, and near-infrared heaters are suitable for such applications.

“Physics of lamp heating”