Methods of metering delivery of caustic soda for treatment of water

Patent metadata

Field	Value
Publication number	US-11485653-B2
Application number	US-202016987968-A
Country	US
Kind code	B2
Filing date	Aug 7, 2020
Priority date	Aug 13, 2019
Publication date	Nov 1, 2022
Grant date	Nov 1, 2022

Abstract

Described is a method for treating water with sodium hydroxide. The method can increase the accuracy of the volume of a stock sodium hydroxide solution that is delivered to the water being treated. The method can include pumping a concentrated aqueous sodium hydroxide stock solution with a diaphragm pumping system that has a two-part diaphragm assembly with a polymeric diaphragm overmolded onto a rigid insert. The polymeric diaphragm can be made of a fully-vulcanized ethylene propylene diene monomer rubber that is injection molded over the rigid insert.

First claim

What is claimed is:

1. A method for treating drinking water, comprising:
providing a stock solution comprising water and sodium hydroxide, wherein the sodium hydroxide in the stock solution has a concentration of between 10% and 70%;
bringing the stock solution into contact with a fully-vulcanized ethylene propylene diene monomer (EPDM) rubber, wherein the EPDM rubber has a density of 0.96 grams per cubic centimeter, a Shore Hardness (Shore A, 23° C.) of 93, a tensile stress at 100% (across flow, 23° C.) of 7.10 MPa, a tensile strength at break (across flow, 23° C.) of 17.6 MPa, an elongation at break (across flow, 23° C.) of 580%, a tear strength (across flow, 23° C., Die C) of 54 kN per meter, a compression set (70° C., 22 hour, Type 1) of 36%, and a brittleness temperature of −54° C. to create a modified solution; and
pumping the modified solution into a volume of the drinking water to treat the drinking water.

2. The method of claim 1 , wherein the sodium hydroxide in the stock solution has the concentration of between 30% and 70%.

3. The method of claim 1 , wherein the sodium hydroxide in the stock solution has the concentration of between 40% and 60%.

4. A method for treating drinking water, comprising:
providing a stock solution comprising water and sodium hydroxide, wherein the sodium hydroxide in the stock solution has a concentration of between 10% and 70%;
bringing the stock solution into contact with a polymeric diaphragm, wherein the polymeric diaphragm comprises a fully-vulcanized ethylene propylene diene monomer (EPDM) rubber overmolded onto a rigid insert to create a modified solution; and
pumping the modified solution to deliver a volume of the modified solution into a volume of the drinking water to treat the drinking water.

5. The method of claim 4 , wherein the fully-vulcanized EPDM rubber overmolded onto the rigid insert has a density of 0.96 grams per cubic centimeter, a Shore Hardness (Shore A, 23° C.) of 93, a tensile stress at 100% (across flow, 23° C.) of 7.10 MPa, a tensile strength at break (across flow, 23° C.) of 17.6 MPa, an elongation at break (across flow, 23° C.) of 580%, a tear strength (across flow, 23° C., Die C) of 54 kN per meter, a compression set (70° C., 22 hour, Type 1) of 36%, and a brittleness temperature of −54° C. and the stock solution is brought into contact with the polymeric diaphragm to create the modified solution.

6. The method of claim 4 , further comprising:
calibrating a pumping system that comprises the polymeric diaphragm, wherein the calibrating comprises: (i) pumping with the polymeric diaphragm a calibration solution at a plurality of operating conditions of the pumping system, and (ii) measuring a volumetric outflow of the pumping system for each of the plurality of operating conditions.

7. The method of claim 6 , wherein the calibration solution has a viscosity that matches a viscosity of the stock solution.

8. The method of claim 6 , wherein the calibration solution comprises the stock solution comprising the water and the sodium hydroxide.

9. The method of claim 4 , wherein the concentration of the sodium hydroxide is between 30% and 70%.

10. The method of claim 4 , wherein the concentration of the sodium hydroxide is between 40% and 60%.

Assignees

• Blue White Ind Ltd

Inventors

• Gledhill Iii Robert E
• Nguyen John T
• Smith Steven Lee

Classifications

• F04B15/02

  the fluids being viscous or non-homogeneous · CPC title

• C02F1/686 Primary

  Devices for dosing liquid additives · CPC title

• C08F210/18

  with non-conjugated dienes, e.g. EPT rubbers · CPC title

• F04B43/0054

  particularities of the flexible members · CPC title

• F04B43/02 Primary

  having plate-like flexible members, e.g. diaphragms (F04B43/14 takes precedence) · CPC title