Intravenous injection apparatus and needle adapter with filter and method of making same

A method of making a needle adapter and filter therefor from flat filter material to increase the filter area comprising the steps of:

• providing a hollow tubular filter housing having a bore therethrough and a marginal edge at one end thereof surrounding said bore;
• positioning the other end of said housing on a support;
• orienting a web of flat filter material over said filter housing one end;
• cutting a section of flat filter material from said flat web;
• engaging a sealing element with said filter material and producing a dome-shaped filter of increased filtering area by pressing said flat filter material onto said housing marginal edge rapidly enough to cause air located between said filter material and said bore to become trapped therebetween and to deform that filter material located adjacent said bore into a dome-shaped configuration, and simultaneously sealing said deformed filter material to said housing marginal edge so that the filter material remains in said dome-shaped configuration to thereby increase the amount of filtering area associated with said filter housing, and completely sealing said deformed filter to said housing so that all of a solution passing through said bore passes through said dome-shaped filter material and leakage therearound is effectively prevented;
• removing said tubular filter housing with said dome-shaped filter secured thereto from said support;
• and
• securing said filter housing with said dome-shaped filter sealed thereon in the bore of a hollow needle adapter housing.