Heaters for gases

Claim 1

AN ELECTRICAL HEATER FOR GASES, SAID HEATER COMPRISING A HOLLOW CLOSED CASING, A PLURALITY OF TUBULAR ELECTRAICAL HEATING ELEMENTS SUPPORTED IN THE CASING IN SPACED RELATION TO THE WALLS THEREOF AND DISPOSED ONE WITHIN THE OTHER IN SPACED CONCENTRIC RELATIONSHIP, MEANS ELECTRICALLY CONNECTING SAID ELEMENTS IN PARALLEL, SAID ELEMENTS BEING FORMED OF METAL MESH TO PROVIDE PASSAGES THERETHROUGH FOR A GAS TO BE HEATED, GAS INLET AND OUTLET MEANS CONNECTED TO THE CASING, MEANS WITHIN SAID CASING PROVIDING A PATH FOR GAS FLOW WITHIN THE CASING THROUGH THE PASSAGES IN SAID ELEMENTS IN A GENERALLY RADIAL DIRECTION BETWEEN SAID INLET AND OUTLET MEANS, A RADIATION SHIELD DISPOSED WITHIN SAID CASING SURROUNDING SAID ELEMENTS AND SPACED OUTWARDLY OF THE OUTERMOST HEATING ELEMENTS AND INWARDLY FROM THE CASING SIDE WALL TO REDUCE REDIATION OF HEAT FROM SAID OUTERMOST ELEMENT TO THE SIDE WALL OF THE CASING, SAID SHIELD BEING DISPOSED IN THE PATH OF GAS FLOW BETWEEN SAID INLET AND OUTLET MEANS TO DIRECT THE FLOW OF GAS SUBSTANTIALLY LONGITUDINALLY OF SAID ELEMENTS, SAID SHIELD HAVING GAS FLOW OPENINGS SPACED LONGITUDINALLY THEREOF AND GRADED IN SIZE TO CAUSE THE GAS TO BE SUBSTANTIALLY EQUALLY DISTRIBUTED ALONG THE LENGTH OF THE HEATING ELEMENTS.