US 11,953,487 B2
Apparatus for measuring water hardness using ion selective electrode
Malcolm Kahn, Franklin Lakes, NJ (US); Robert Astle, Middlefield, CT (US); Jeffrey Zimmerman, Forest Lake, MN (US); and Ravi Meruva, Lexington, MA (US)
Assigned to Ecowater Systems LLC, Woodbury, MN (US)
Filed by Ecowater Systems LLC, Woodbury, MN (US)
Filed on Jun. 15, 2022, as Appl. No. 17/841,228.
Application 17/841,228 is a division of application No. 17/235,136, filed on Apr. 20, 2021, granted, now 11,391,713.
Application 17/235,136 is a division of application No. 16/369,925, filed on Mar. 29, 2019, granted, now 11,016,074, issued on May 25, 2021.
Claims priority of provisional application 62/649,932, filed on Mar. 29, 2018.
Prior Publication US 2022/0317105 A1, Oct. 6, 2022
Int. Cl. G01N 33/18 (2006.01); C02F 1/42 (2023.01); G01N 27/333 (2006.01)
CPC G01N 33/1853 (2013.01) [C02F 1/42 (2013.01); G01N 27/333 (2013.01); G01N 33/1813 (2013.01); G01N 33/1893 (2013.01); C02F 2209/055 (2013.01); C02F 2303/16 (2013.01)] 9 Claims
OG exemplary drawing
 
1. An apparatus for determining hardness in water, said apparatus comprising:
a first sodium ISE sensor coupled with a first reference electrode, said first sodium ISE sensor configured to receive hard water;
a second sodium ISE sensor coupled with a second reference electrode, said second sodium ISE sensor in electrical communication with said first sodium ISE sensor, and configured to receive soft water;
first and second dialysis membranes in separate chambers, having a salt bridge solution between the first and second sodium ISE sensors; and
at least one drain to receive outflow from effluent fluid from said first and second sodium ISE sensors;
wherein said first and second sodium ISE sensors comprise a standalone system providing an Na value and in communication with said salt bridge solution, establishing functionality as a differential sodium ISE; and
said apparatus is sealed so as to not lose said salt bridge solution.