Finned armoured heaters
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FINNED ARMOURED HEATERS Application: Heaing of Air and Gases Figure 1: Typical sketch of a finned armoured heater GENERAL CHARACTERISTICS The finned armoured heaters have been developed to satisfy the need of temperature controlled air or gas flows which is present in several industrial processes. They are also suitable to keep a closed ambient at a specified temperature The are designed to be inserted into ventilation ducts or air conditioning plants and are directly flown by the process air or gas. They can also be installed directly inside the ambient to be heated since they are suitable to heat static air or gases. These heaters are finned to increase the heat exchange. However, if the heated fluid contains particles (which could clog the fins) these heaters cannot be used and smooth armoured heaters shall be used in place. The heaters undergo dimensional and electrical controls all along the production phase, as required by the company Quality Control System (certified in accordance with ISO 9001:2000 Standard). A 100 % electrical acceptance test allows to verify the compliance of each single heater to the requirements specified in the applicable CEI/EN Specification. In particular, the following tests are performed: TECHNICAL DATA (see Figure 1) 1. TERMINAL STUD threaded M6 (heaters with 16 mm diameter sheath) or M4 (heaters with 10 mm diameter sheath) made of stainless steel AISI303 NUTS made of stainless steel AISI304 WASHER made of stainless steel AISI304 INSULATING BUSH made of steatite KER221 SILICON SEALING suitable for high temperatures SHEATH (or ARMOUR) made of carbon steel or titanium-alloyed stainless steel AISI316Ti, particularly suitable for high temperatures ELECTRIC INSULATION obtained by a high purity MgO powder, suitable for high temperature, with a grains size distribution optimised for this application RESISTIVE WINDING spiral made of Nickel/ Chrome 80/20 DIN 17470, executed with automatic tools which insure long duration EXTERNAL FIN obtained by wounding a 0.5 mm thick ribbon (pitch = 4.5 mm) made of UNI 5866 carbon steel (in case of heaters with carbon steel sheath) or in stainless steel AISI304 (in case of heaters with AISI316Ti sheath). 2. 3. 4. 5. 6. 7. 8. 9. The manufacturing options are sketched in Figure 2 Figure 2: manufacturing options of finned armoured heaters Measurement of the Insulation resistance Measurement of the dielectrical rigidity Measurement of the dispersion current Measurement of the resistance ohmic value APPLICATIONS These heaters are used in the heating of closed areas, in air conditioning plants, in the forced ventilation used as part of packaging processes and in drying ovens. A proper choice of the construction materials allows to reach fluid operating temperatures up to 300 400 °C. POSSIBLE MATERIAL COMBINATIONS: 1) Sheath and Fin in carbon stee 2) Sheath in AISI316Ti + Fin in AISI304 O o Sheath in AISI316Ti Fin in AISI304 o o 6

AMSRfyfiFT_FINNED ARMOURED HEATERS Application: Heating of Air and Gases POWER The finned armoured heaters are normally manufactured with a specific power in the range 2^4 W/cm2. If the air or gas flow is sufficiently high, specific power values up to 6^8 W/cm2 can be reached To select, amongst all possible solutions, the one that best suits the application of interest, the customer shall specify at least: ■ The fluid to be heated (air or other) ■ The type of heating (static or in forced convection) and the temperatures that the fluid shall reach ■ The power supply voltage ■ The desired...

AMSRfyfiFT_FINNED ARMOURED HEATERS Application: Heaing of Air and Gases Figure 5: dimensions and constructive characteristics of fixation devices for lments with sheath diameter 10 mm STANDARD ON STOCK HEATERS In many cases the heating needs are not very complex but, on the other hand, it is necessary to have the heaters available at a reduced cost and in a limited time. LOVAR finned heaters have been conceived just to respond to this need: they can heat static air (version with specific power equal to 2 W/cm2) or air in forced flow (versions with specific power equal to 3 and 4 W/cm2)....