Method of TOC monitoring
View Patent ↗A method of determining the TOC of a purified water stream is disclosed comprising at least the steps of: passing a supply water stream through a water purification apparatus including an oxidizer to provide a purified water stream, and dispensing at least a portion of the purified water stream; stopping the dispense of the purified water stream and recirculating the purified water stream as a recirculating water stream through at least a portion of the water purification apparatus including the oxidizer to provide a re-oxidized water stream; and measuring the conductivity value of the re-oxidized water stream to determine the TOC of the purified water stream. In this way, a determination of the TOC of the purified water stream of can be provided without requiring a dedicated TOC monitor at the point of dispense of the purified water stream.
1. A method of determining the total organic carbon (TOC) of a purified water stream, comprising at least the steps of:
(a) passing a supply water stream through a water purification apparatus including an oxidiser and one or more ion-exchangers downstream of the oxidiser, to provide a purified water stream, and dispensing at least a portion of the purified water stream through a valve at a point of dispense as a dispensed stream;
(b) stopping the dispense of the purified water stream by operating the valve to move between a dispense position and a recirculating position and recirculating the purified water stream as a recirculating water stream through at least a portion of the water purification apparatus including the oxidiser to provide a re-oxidised water stream;
(c) measuring a conductivity value of the recirculating water stream prior to the oxidiser at a first location in the water purification apparatus that is prior to any ion-exchangers so as to provide a conductivity measurement of the recirculating water stream;
(d) channeling the recirculating water stream from the first location to the oxidiser without passing through any ion-exchangers;
(e) measuring a conductivity value of the re-oxidised water stream at a second location downstream from the oxidiser and prior to the re-oxidised water stream passing through any ion-exchangers; and
(f) using the measurements to determine the TOC of the purified water stream of step (a) at the point of dispense of the purified water stream.
2. A method as claimed in claim 1 wherein the water purification apparatus at least comprises: a water inlet, a pump, an oxidiser, a de-ioniser, and a water outlet.
3. A method as claimed in claim 2 wherein the oxidiser comprises one or more ultraviolet light emitters.
4. A method as claimed in claim 2 wherein the recirculating water stream is delayed in the oxidiser in step (b).
5. A method as claimed in claim 2 further comprising measuring the conductivity value of the purified water stream dispensed and/or assuming a conductivity value for the recirculating water stream prior to the oxidiser, and using said value in determining the TOC of the purified water stream.
6. A method as claimed in claim 2 to calibrate and/or increase the accuracy of the estimation of TOC in the purified water stream during a dispense, the estimate of the TOC being determined from the measurement of the difference in conductivity values between the supply stream and the post oxidiser water stream during the dispense.
7. A method as claimed in claim 1 wherein the oxidiser comprises one or more ultraviolet light emitters.
8. A method as claimed in claim 7 wherein the recirculating water stream is delayed in the oxidiser in step (b).
9. A method as claimed in claim 7 further comprising measuring the conductivity value of the purified water stream dispensed and/or assuming a conductivity value for the recirculating water stream prior to the oxidiser, and using said value in determining the TOC of the purified water stream.
10. A method as claimed in claim 7 to calibrate and/or increase the accuracy of the estimation of TOC in the purified water stream during a dispense, the estimate of the TOO being determined from the measurement of the difference in conductivity values between the supply stream and the post oxidiser water stream during the dispense.
11. A method as claimed in claim 1 wherein the recirculating water stream is delayed in the oxidiser in step (b).
12. A method as claimed in claim 11 further comprising measuring the conductivity value of the purified water stream dispensed and/or assuming a conductivity value for the recirculating water stream prior to the oxidiser, and using said value in determining the TOC of the purified water stream.
13. A method as claimed in claim 11 to calibrate and/or increase the accuracy of the estimation of TOC in the purified water stream during a dispense, the estimate of the TOC being determined from the measurement of the difference in conductivity values between the supply stream and the post oxidiser water stream during the dispense.
14. A method as claimed in claim 1 further comprising measuring the conductivity value of the purified water stream dispensed and/or assuming a conductivity value for the recirculating water stream prior to the oxidiser, and using said value in determining the TOC of the purified water stream.
15. A method as claimed in claim 1 to calibrate and/or increase the accuracy of the estimation of TOC in the purified water stream during a dispense, the estimate of the TOC being determined from the measurement of the difference in conductivity values between the supply stream and the post oxidiser water stream during the dispense.