| 摘要 |
<p>1,108,144. Compressors. CALUMET & HECLA Inc. April 4, 1966 [June 28, 1965], No. 14972/66. Heading FIN. Prior to welding a length of refrigerator tubing 12 Fig. 1 to an external support, the tube 12 is purged with compressed nitrogen from a source 28, opposite ends 24, 26 of the tube 12 are then closed by resilient plugs 16, 18 a hollow needle 132 Fig. 4 connected to a compressed nitrogen source 90 is inserted through plug 18 and when the tube is charged to the desired pressure the needle is removed from plug 18 and the welding operation carried out without oxidation of the tube interior and finally the plugs 16, 18 are removed. The duration of purging is controlled by a conventional electrical timing circuit which includes a solenoid valve 34 in the line 32 between the nitrogen source 28 and a tubular member 30 in sealing abutment with the adjacent end 24 of the tube 12. The duration of charging of tube 12 from nitrogen source 90 through a solenoid valve 92 is similarly controlled.</p> |
