Apparatus for annealing magnetic iron

Claim 1

IN A HYDROGEN ANNEALING APPARATUS, A FURNACE HAVING AN INNER CHAMBER FOR RECEIVING PARTS TO BE ANNEALED AND AN OUTER CHAMBER ENCLOSING SAID INNER CHAMBER, OUTLETS FROM SAID CHAMBERS, CONDUIT MEANS FROM SAID CHAMBERS TO A SUPPLY OF NITROGEN, CONDUTI MEANS FROM SAID INNER CHAMBER TO A SUPPLY OF HYDROGEN, ELECTRICALLY OPERATED VALVE MEANS IN SAID CONDUIT MEANS HAVING A NORMAL POSITION OPERABLE TO SHUT OFF THE FLOW OF NITROGEN TO THE OUTER CHAMBER AND THE FLOW OF HYDROGEN TO THE INNER CHAMBER AND TO ESTABLISH A FLOW OF NITROGEN TO THE INNER CHAMBER TO FLUSH THE ATMOSPHERE THEREFROM, A GAS ANALYZER CONNECTED TO THE OUTLET FROM SAID INNER CHAMBER FOR INDICATING THE RELATIVE DENSITIES OF THE GASES PURGED FROM SAID INNER CHAMBER AND HAVING A CONTROL SWITCH OPERABLE IN RESPONSE TO THE FLOW OF SUBSTANTIALLY PURE NITROGEN THEREIN, MEANS INCLUDING A SWITCH OPERABLE IN COOPERATION WITH SAID CONTROL SWITCH TO CONNECT SAID ELECTRICALLY OPERATE VALVES TO A SOURCE OF POWER TO ACTUATE SAID VALVE MEANS TO ANOTHER POSITION TO SHUT OFF THE FLOW OF NITROGEN AND ESTABLISH A FLOW OF HYDROGEN TO SAID INNER CHAMBER AND TO ESTABLISH A FLOW OF NITROGEN TO SAID OUTER CHAMBER, ELECTRICAL HEATING ELEMENTS IN SAID OUTER CHAMBER, AND MEANS TO CONNECT SAID HEATING ELEMENTS TO A SOURCE OF POWER.