| 摘要 |
1469843 Medical filter SHERWOOD MEDICAL INDUSTRIES Inc 15 March 1974 [25 April 1973] 11753/74 Heading BID [Also in Divisions A5 and C7] A filter element of sintered stainless steel is made by screening particles of irregular shape to exclude those outside a given size range, mixing the remaining particles with 0.05 to 0.5% weight of lubricant e.g. wax, pressing them to form a self-supporting 'green' filter element and heating the element in two stages to burn off the lubricant and sinter the particles. Particle size ranges exemplified are 44-74 and 125-149 microns, which produce elements capable of retaining 99% of impurities above 3 and 10 microns dia. Numerical details of pressures, dimensions and sintering parameters are disclosed. The element may be cup shaped as shown or rounded or flat. The element is then force-fitted into a tube of polypropylene, polycarbonate or polyethylene terephthalate and heated by induction (Fig. 4 not shown) to form a peripheral seal therewith. The resulting filter is used in a hypodermic syringe or an intravenous infusion set. |
