Method of inserting a close-fitting flexible heater element into an armored passage

Claim 1

IN THE ART OF FABRICATING HEATING APPLIANCES THE STEPS COMPRISING, PROVIDING A SHEET OF METALLIC MATERIAL HAVING AN ELONGATED OPEN-ENDED PASSAGE OF A UNIFORM CROSS SECTIONAL AREA FORMED THEREIN AND DISPOSED IN A TORTUOUS PATH IN THE PLANE OF SAID SHEET, ARRANGING IN END-TO-END RELATION WITH ONE END OF SAID PASSAGE AN ELONGATED, FLEXIBLE, INSULATED HEATING ELEMENT HAVING A UNIFORM CROSS SECTIONAL AREA ONLY SLIGHTLY LESS THAN THAT OF SAID PASSAGE AND WITH SAID ELEMENT CONFINED LOOSELY WITHIN AN ELONGATED HOLLOW HOLDER HAVING ONE END DISPOSED IN FLUID COMMUNICATION WITH SAID ONE END OF SAID PASSAGE, VIBRATING SAID ELEMENT BY INTRODUCING A FLUID UNDER SUPER-ATMOSPHERIC PRESSURE FROM THE OTHER END OF SAID HOLDER AND LENGTHWISE OF SAID ELEMENT INTO AND THROUGH SAID PASSAGE, AND CONTINUING TO INTRODUCE SAID FLUID PRESSURE INTO SAID PASSAGE WHILE SIMULTANEOUSLY CAUSING THE RESULTING FLUID STREAM TO EJECT SAID ELEMENT WITH A VIBRATORY MOVEMENT FROM SAID HOLDER INTO SAID PASSAGE, THEREBY TO EMPLACE SAID ELEMENT WITHIN SAID PASSAGE WITHOUT DAMAGING SAID INSULATION.