Patent ID: 6416669
Filing Date: 2002-07-09
Classification: C02F

Abstract:
A method of producing ultrapure water, comprising the steps of:passing water through a resin bed and intimately contacting the water with resin particles in the resin bed to remove ions and minerals from the water and thereby purify the water; advancing the purified water from the resin bed into a resin trap device external from said resin bed, the resin trap device comprising a housing and resin strainer disposed within the housing, the resin strainer including a plurality of openings having a particle pass size of between about 100 m and about 250 m; retaining large particles having a diameter of greater than the particle pass size of the openings in the resin trap device; allowing water and small particles having a diameter of less than the particle pass size of the openings to flow out of the resin trap device; and filtering the from said advancing step through an ultrafilter downstream from the resin trap device to produce ultrapure water having a specific resistivity of greater than or equal to 18 MÂ·ohmÂ·cm at 20Â° C.; wherein said method is free of microfiltration steps between said advancing step and said filtering step wherein the water is filtered through microfilters having a maximum particle pass size of between 0.1 &mgr;m and 1 &mgr;m.