Patent ID: 11865240
Assignee: NXSTAGE MEDICAL, INC.
Field: Environmental technology (Chemistry)
Classification: CPC A  C | IPC A  C

Claim 6:
7. A method for purifying water to produce a product water meeting a predefined water quality requirement that includes a predefined limit on an amount of chloramine and a lower limit on an allowed resistivity of said product water due to all dissolved species, the method comprising:
removing the chloramine from a stream of primary water using a first filter to produce primary water depleted of the chloramine;
using a second filter, filtering the primary water depleted of the chloramine to reduce other dissolved species sufficient to produce high resistivity product water whose resistivity is sufficiently high to permit detection of the chloramine using a resistivity detector;
using a controller, predicting, based on a parameter that is responsive to time of use of the first filter, and outputting from the controller, a first signal indicating a requirement to replace the first filter, the predicting being such that there is a sufficient remaining capacity to remove the chloramine from the stream of the primary water to ensure that said product water meets said predefined limit on the amount of the chloramine under non-error conditions;
using the controller, monitoring the resistivity of the high resistivity product water and determining a chloramine concentration in the high resistivity product water from the resistivity and a temperature measurement; and
generating a second signal indicating a product water quality error responsively to determining that the chloramine concentration exceeds the predefined limit.