Radiant heat source

Sometimes, in FD, the emitter electrode is heated gently either directly by an electrode current or indirectly by a radiant heat source to aid desorption of ions from its surface. 

If an enclosure may be divided into several radiant-heat sources or sinks Ai, A2, etc, and the rest of the enclosure (reradiating refractoiy surface) may be lumped together as A at a uniform temperature Tr, then the total interchange area for zone pairs in the black system is given by... 

Radiative Heat Transfer Heat-transfer equipment using the radiative mechanism for divided solids is constructed as a table which is stationary, as with trays, or moving, as with a belt, and/or agitated, as with a vibrated pan, to distribute and expose the burden in a plane parallel to (but not in contacl with) the plane of the radiant-heat sources. Presence of air is not necessary (see Sec. 12 for vacuum-shelf dryers and Sec. 22 for resubhmation). In fact, if air in the intervening space has a high humidity or CO9 content, it acts as an energy absorber, thereby depressing the performance. 

Standard Methods of Fire Tests of Door Assemblies, 1990 (similar to ASTM E-152). Standard Method of Test for Critical Radiant Flux of Floor Covering Systems Using a Radiant Heat Source Energy Source, 1990 (similar to ASTM E 648). 

When a combustible material is exposed to an external radiant heat source, its surface temperature starts to rise. The temperature inside the solid also increases with time, but at a slower rate. Provided the net heat flux into the material is sufficiently high, the surface temperature eventually reaches a level at which thermal decomposition begins. The fuel gases and vapors generated emerge through the exposed surface and mix with air in the gas phase. Under certain conditions, this mixture exceeds the lower flammability limit and ignites. 

FIGURE 16.11 RPA with a gas radiant heat source and a ceramic sample holder. 

ISO 5657, Reaction to Fire Tests—Ignitability of Building Products Using a Radiant Heat Source, International Organization for Standardization, Geneva, Switzerland. 

ASTM E 906 Heat and Visible-Smoke-Release Rate Test (based on Ohio State University Release Rate Apparatus). In this test the specimen is injected into an environmental chamber through which a constant flow of air passes. A radiant-heat source is used to produce the desired heat flux in the specimen, which way be tested horizontally or vertically. Combustion may be initiated by a number of different methods. The changes in temperature and optical density of the gas leaving the chamber are monitored, and from the resultant data the heat-release rate and visible anoke-release rate are calculated. Toxic-gas release and oxygen consumption rates may also be measured. 

Thermal treatment may use either direct or indirect heating. Direct heating uses direct contact with combustion gas or heat carrier gas to heat the contaminated media. Indirect heating inputs heat by contacting the debris with a heated wall, screw impeller, or other device. The device is in turn heated by an external source, such as a heat transfer fluid (e.g., hot oil or hot gas) or a radiant heat source. 

Two square plates are to be glued together by means of a radiant heat source, q", acting on one plate (Fig. 3P-1). The glue becomes effective at a temperature Tm. The ambient temperature is. It may be assumed that 3i and z are small, k and k-s are large, so that lumped conditions prevail. Find the time required to obtain a bond between the plates. 

The intensity of the radiation is a function of the fourth power of the temperature of the heated object. This means that a radiant heat source operating at several hundred degrees will have a high rate of heat transfer toward a substrate at temperatures up to a few hundred degrees, providing the substrate is not highly reflective or transparent toward the emitted infrared. In practice, a filament is heated by gas or electricity and the radiant energy is directed toward the substrate by means of reflectors. 

This ASTM test will be briefly described here. The test is not intended for use as a basis of rating for building code purposes, as, for example, ASTM E 84. The purpose of the test is to determine the relative surface flammability performance of various materials under specific test conditions under a radiant heat source. 

BS EN 366 (1993), Protective clothing—Protection against heat and fire—Method of test evaluation of materials and materials assemblies when exposed to a radiant heat source. 

The short-wave IR radiation can only be generated by an electric IR heater employing a tungsten heating element. A tungsten filament has small mass as well as low electrical resistance, which allows heavy current flow and very rapid heat up and cool down. The rate of response of various types of radiant heat sources can be an important criterion in the selection of a proper source for coating drying applications. 

Let s first focus on OSHA compliance. As stated in the OSHA Technical Manual Section 111 Chapter four Operations involving high air temperatures, radiant heat sources, high humidity, direct physical contact with hot objects, or strenuous physical activities have a high potential for inducing heat stress in employees engaged in such operations. ... 

ASTME162 (20012a) Standard Test Method for Surface Flammability of Materials Using a Radiant Heat Source. 

Flame spread, critical heat flux, and smoke production rate of floor coverings and floor coatings are measured using a radiant heat source according to DIN 4102-14 and EN ISO 9239 for classifleation into DIN 4102 and Euroclasses. 

Whenever there is a potential for exposure to conditions that may produce bums, there is a need to implement protective strategies. In some cases, engineering controls are necessary. One example is insulating hot surfaces to reduce surface temperatures to levels that will not create bums. Another is providing shields between radiant heat sources and workers. 

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