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topic 52466

What is Cation Conductivity


A discussion started in 2009 but continuing through 2017

June 22, 2009

Q. What exactly is Cation conductivity and how it is beneficial in boiler water?

Prasad Reddy
Researcher - INDIA


June 23, 2009

A. Hi, Prasad. Apparently cation conductivity is not just a property, but a technique:

"In high pressure steam systems, cation conductivity is a useful tool for monitoring return condensate for low levels of contamination by anions such as Cl-, SO4-, HCO3-, etc. In practice, a cooled sample of condensate or high purity water flows through a cation exchanger in the hydrogen form. The cation resin replaces contaminating cations such as Ca++, Mg++, Na+, NH4+, and amines in the sample with hydrogen ions. The hydrogen ions exchanged for the other cations in the sample increase the conductivity contributed by the contaminant salts of mineral acid anions listed above by 3 or 4 times. Thus the cation exchange column can be thought of as a "conductivity amplifier" for mineral and organic acid contaminants; increasing the sensitivity of the conductivity analyzer to low levels of contamination. "

-- per www.gewater.com/pdf/pfe059.pdf

Regards,

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey

----
Ed. note Nov. 2017: Sorry: apparently Suez Water has purchased the gewater.com domain, and no longer maintains educational articles; the link redirects to https://knowledgecentral.suezwatertechnologies.com, but which is now in turn broken :-(



February 13, 2015

Q. The cationic conductivity was well defined.

I would like to clarify --
1. Will Cationic conductivity of live steam be higher than that of the condensate return from the turbine, or both will be same?
2. Is there will be effect of cooling system for steam condensing after exhaust from steam turbine, i.e., air cooled system or water cooled system will have any effect?
3. Is there any Feedwater limit to achieve cationic conductivity < 0.3us/cm?

Thanks

Nisar Ahmad
- Rawalpindi, Pakistan


A. Hi Nisar. This is not a subject within my experience, but ...
1. Based on the paragraph I just quoted, it seems that the cation conductivity techniques can only be applied on "a cooled sample", so the question is actually inapplicable. 2. If any operation introduces contaminants, it will increase conductivity; if not, it won't. 3. Certainly if you want very low conductivity the feedwater must be of very low conductivity; surely as low, and probably lower, than the conductivity you desire in the condensate.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



January 11, 2016

Q. When a sample stream is passed through a specific conductivity meter and then through a cation conductivity meter, which one should read higher? Why?

tom Mattingly
- whitesville, Kentucky, usa


January 2016

? Hi Tom. Which one IS reading higher? :-)

Please try to explain your actual situation for us rather than posing an abstract proposition. This is especially important for a question that is a bit peripheral to our metal finishing focus because most of our readers are unprepared to try to help you without studying up on the topic a bit, and I wouldn't know where to start without a little background in the question :-)

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


January 24, 2016

Q. I work at a power plant and although others and myself monitor cation conductivity, I'm not sure any of us understand it.

Question: a sample stream passes over a specific conductivity meter then through a cation resin column and the cation conductivity meter. Which meter should have a higher reading, the specific or the cation?
Why?
What does cation conductivity measure?

tom mattingly[returning]
tech - whitesville, Kentucky


Hi Tom. Please tell us which of the two meters has been reading the higher conductivity instead of posing a hypothetical.

My understanding, based on the paragraph I quoted, is that the cation conductivity meter should read higher. I am not actually acquainted with this stuff, but it sounds like: if the amount of calcium, magnesium, sodium, and ammonium chlorides, sulfates, and carbonates is very low, the water is not very conductive, and therefore it's very hard to monitor and watch for chloride, sulfate, and carbonates anions. But if you pass the water through a cation exchanger first, hydrogen ions (which are highly conductive) will replace the less conductive Ca++, Mg++, Na+, NH4+ cations in the water, thus rendering the contaminated water more conductive and thus easier to monitor for those anions.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey


November 24, 2016

A. Hi Tom, the specific conductivity meter shows a higher reading than the Cation meter, because the specific conductivity meter is showing total reading of cation+anion but the cation conductivity meter only gives the reading of cation.

Muhammad Saqib
- Islamabad Pakistan


May 10, 2017

A. But if you have contamination of amines in that water, then specific conductivity will show it, and cation conductivity won't. Therefore specific conductivity probably will be higher. You can read about it here:
http://www.mt.com/dam/mt_ext_files/Editorial/Generic/7/Paper-THOR-Gray-CONDUCTIVITY_Editorial-Generic_1201100849793_files/iwc_06-29_gray_conductivity.pdf

"Cation (acid) conductivity is the technique of continuously conditioning the sample by passing it through a hydrogen form cation exchange cartridge. It enhances the sensitivity to contaminants by two means:
-- Ammonia or amines that are intentionally present at ppm levels are removed. This eliminates their high conductivity. The lower ppb concentrations and conductivity of contaminants can then be "seen" by the measurement.
-- Contaminant corrosive salts are converted to their respective acids which are typically three times as conductive as the original salt because of the highly conductive hydrogen ion."

Dmytro Tarianyk
- Cracow, Poland


thumbs up sign Hi Dmytro. Thanks for the excellent reply!

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



How to reduce steam conductivity?

July 7, 2017

Q. Our steam pressure and temperature are 147 barg and 540 °C. Steam cationic conductivity is in the range of 0.3-0.6 µS/cm. This steam is also supplied to our client and they are asking for <0.1 µS/cm. Is it possible to achieve? If yes, how? Thanks.

Jo Jayakumar
- Chennai, Tamilnadu, India



November 22, 2017

Q. What is the difference between Cation Conductivity & Electrical Conductivity in Water samples?

Waqar Khan
National Refinery Limited - Karachi, Sind, Pakistan


November 2017

A. Hi cousin Wagar. Cation conductivity is a technique as well as a measurement. Before measurement, the water is passed through a cation exchanger which both removes amines and increases the sensitivity to anion presence by replacing the Calcium, Magnesium, and Sodium cations with hydrogen ... which makes the water 3 to 4 times more conductive.

If careful study of this page doesn't clarify it for you, please phrase your question like: "I understand that ... but what I am not understanding is ..." so we can see where the difficulty lies. Good luck.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



March 4, 2018

Q. Though here have mentioned cation conductivity will remove effect of ammonia contamination in practical here when high feed of ammonia increase cation conductivity. Why that observation? Apart from cation column have been placed a degasser as well. But this observation can see. This increase is done by ammonia ions or contaminants in ammonia solution?

Geethani Weerskon
- Colombo, Sri Lanka



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