Seal structure of explosion-proof Characteristic electric heater and external container, means for supporting null of seal component and external

摘要

PURPOSE:To enable an external container to bellow a thermal expansion of a heat exchanging part by a method wherein gas with a pressure higher than a surrounding air pressure is filled in a clearance of the container and a part of a circumferential wall of the external container is provided with a fold structure for accommodating a thermal expansion. CONSTITUTION:Although a heat exchanging part 2 is air-tightly stored in an external container 1, gas of which pressure is higher than a surrounding air pressure is filled in a clearance in the container so as to prevent external explosive gas from entering the container. A fold structure 16 arranged at a substantial central part of the external container 1 is provided with a bellows pipe at a central part of the external container 1. In case of a thermal expansion of a heat exchanging part 2 due to a presence of this fold structure 16, the thermal expansion at the external container 1 is accommodated at this fold structure 16, resulting in that a deformation and a breakage of the external container 1 are prevented. A sheet 21 not allowing air permeation has a heat-resistant characteristic and a softness. A large- diameter feeding-out part is installed at a small diameter through-hole 22 and then a close curved part 23 along an outer shape of the feeding-out part is applied. At the through-hole 25, a pushing plate 24 fitted to the feeding-out part and fastened with bolts to an opening edge of the external container 1 may fasten and fix the circumferential edge of the sheet 21 under its compressed state.