A hollow fiber membrane contactor comprising: a cartridge having two ends; said cartridge comprising; a perforated center tube having a first end and a second end; a hollow fiber fabric comprising hollow fiber membranes, each said hollow fiber membrane having a first end, a second end, and a lumen, said hollow fiber fabric surrounding said center tube; a first tube sheet and a second tube sheet being formed from an integral potting material and affixing said fabric to said center tube at each end of said center tube ends; a plug in said first end of said center tube and located at said first tube sheet; and said fiber lumens being open at said fiber first ends at the first tube sheet and said hollow fiber lumens being closed at said fiber second ends at the second tube sheet; a shell having two ends (21, 23) and an opening through said shell, said shell being adapted to enclose said cartridge; said tube sheets (18, 20) being sealed to said shell by the integral potting material forming tube sheets (18, 20), thereby forming a cartridge-shell assembly; characterized in that said cartridge ends extending equally with said shell ends and that the hollow fiber membrane contactor further comprises a first end cap having an opening therethrough; said first end cap being adjoined to said first end of said shell where said first end cap and said first tube sheet defining a first head space therebetween; said first end cap opening being in fluid communication with hollow fiber lumens via said first head space; a second end cap having an opening therethrough; said second end cap being adjoined to said second end of said shell where said second end cap and said second tube sheet defining a second head space therebetween, said second end cap opening being in fluid communication with said center tube via said second head space. a cartridge having two ends; said cartridge comprising; a perforated center tube having a first end and a second end; a hollow fiber fabric comprising hollow fiber membranes, each said hollow fiber membrane having a first end, a second end, and a lumen, said hollow fiber fabric surrounding said center tube; a first tube sheet and a second tube sheet being formed from an integral potting material and affixing said fabric to said center tube at each end of said center tube ends; a plug in said first end of said center tube and located at said first tube sheet; and said fiber lumens being open at said fiber first ends at the first tube sheet and said hollow fiber lumens being closed at said fiber second ends at the second tube sheet; a shell having two ends (21, 23) and an opening through said shell, said shell being adapted to enclose said cartridge; said tube sheets (18, 20) being sealed to said shell by the integral potting material forming tube sheets (18, 20), thereby forming a cartridge-shell assembly; characterized in that said cartridge ends extending equally with said shell ends and that the hollow fiber membrane contactor further comprises a first end cap having an opening therethrough; said first end cap being adjoined to said first end of said shell where said first end cap and said first tube sheet defining a first head space therebetween; said first end cap opening being in fluid communication with hollow fiber lumens via said first head space; a second end cap having an opening therethrough; said second end cap being adjoined to said second end of said shell where said second end cap and said second tube sheet defining a second head space therebetween, said second end cap opening being in fluid communication with said center tube via said second head space.