Safety in electroheat installations – Part 2: Particular requirements for resistance heating equipment
|Publication Date:||1 August 2006|
|ICS Code (Electric furnaces):||25.180.10|
This part of IEC 60519 is applicable to the indirect resistance heating equipment and the direct resistance heating equipment specified in items a) and b) below respectively, operating in voltage bands 1 and 2.
The object of this standard is the standardization of safety requirements for both indirect and direct resistance heating equipment described below.
a) Indirect resistance heating equipment
These particular requirements apply to equipment for indirect resistance heating, such equipment being energized with d.c. voltage or with single-phase or multiphase a.c. voltage of frequency up to 60 Hz.
Heat generation is effected by current flow in
− solid metallic heating conductors;
− solid non-metallic heating conductors;
− radiant tubes and immersion heaters.
Examples of indirect resistance heating equipment in general use include
− discontinuous furnaces such as batch-type furnaces, muffle furnaces, pot-type furnaces (crucible furnaces), pit-type furnaces, bell-type furnaces, bogie-hearth furnaces, fluidizedbed furnaces, immersion heater metal baths;
− continuous furnaces with continuous or discontinuous charge conveyors, such as rollerhearth furnaces, pusher furnaces, walking-beam furnaces, rotary-retort furnaces, rotaryhearth furnaces, tunnel furnaces (kilns), continuous muffle furnaces.
Indirect resistance heating equipment in general use also includes −
equipment for heating solids, liquids or gases;
− equipment for melting and holding;
− individual heating-element assemblies (movable or fixed heaters).
Indirect resistance heating equipment where particular hazards are likely to occur includes
− nitrite bath furnaces;
− indirect resistance heating equipment where an explosive atmosphere is likely to occur inside the furnace during heat treatment: furnaces for carburizing in gas atmospheres consisting of the mixture of hydrogen and methane or propane and carbon monoxide;
− indirect resistance heating equipment with protective gas and/or reaction gas atmosphere: furnaces for gas carburizing, gas nitriding, carbo-nitriding (protective gas, for example, argon);
− equipment with infrared heating elements.
These requirements do not apply to trace heating systems dealt with in IEC 60519-10.
b) Direct resistance heating equipment
These particular requirements also apply to equipment for direct resistance heating by means of current introduced by electrodes passing through the charge or a fluid to be heated. Such equipment includes, for example,
− salt-bath electrode furnaces;
− glass-melting furnaces;
− furnaces for graphitizing;
− furnaces for production of silicon carbide.
These requirements do not apply to equipment for direct resistance heating, where, owing to the technology used, IEC 60519-3, IEC 60519-4, IEC 60519-8 and IEC 60519-21 are applicable. Moreover, they do not apply to electrode-steam-boil