11 replies to this topic

[anju]

How to check % of chlorine? our Engineering dept. using 10% chlorine for chlorination purpose. I just want to check strength of chlorine. can any one help me

[Mike Carr]

It works a bit like litmus paper, you can test for chlorine using paper strips and compare the colour shade to a chart to find out the level of chlorine.

I would hope there is a digital device you can get as a solution from somewhere, but it might set you back a few more pennies!

Mike

[anju]

Thanks Mike
I knew about that litmus paper for checking chlorine strength in PPM. I want to know how to check % of the chlorine? Like if it says 5% chlorine means is it in that % or not? thats i want to check? is there any titration method for this.Pls let me know

[Charles.C]

Dear anju,

Can try this one if it doesn't hv to be an 'official" procedure, looks fairly typical from long memory although i don't seem to remember using quite so much indicator (1-2ml??) -

 laboratory_analyses_1.doc   158.5KB   160 downloads

Rgds / Charles.C

[antoni sola]

Anju,
Visit this website: http://www.hannainst...india/index.cfm
There's a large range of products for the chloride measurement.

[cazyncymru]

How to check % of chlorine? our Engineering dept. using 10% chlorine for chlorination purpose. I just want to check strength of chlorine. can any one help me

see attached, it may help

Attached Files

•  LTM_15.doc   21.5KB   114 downloads
•  WIL_26.DOC   25.5KB   85 downloads

[Brianp]

You can correlate % chlorine to PPM fairly easily. 10% chlorine would be 100,000 PPM (because 1 million parts per million would be 100%.)

What is the purpose of the chlorination? 10% is a huge amount of chlorine for a food operation! Commercial bleach contains less chlorine than that! Many people assume that 1 Liter of bleach = 1 Liter of chlorine. This is not so. Bleach is only approximately 2.5% chlorine. Are you making a solution of 10% bleach or 10% chlorine? There is a big difference.

If your goal is to kill bacteria then you should be shooting for 200 PPM chlorine and pH 7 at the most. You can monitor the strength of the chlorine by measuring the oxidation reduction potential (ORP.) If the ORP is greater than 500 or so then you're reliably killing vegetative bacteria. At 200 PPM I'd expect your ORP to be closer to 800 if you're maintaining the pH properly.

ORP is the best way to monitor the bactericidal effectiveness of a chlorine solution. PPM is good for a spot check if your solution is free of organic solids but if the water gets dirty the chlorine will be less effective at the same PPM.

[Charles.C]

Dear Caz,

Useful colorimetric methods, esp. the popular DPD one, but (I expect) less accurate than titration (which apparently also not that perfect [as per my link]). Maybe good enough for anju though if willing to buy the comparator.

Sadly, all these methods are a bit nose-hand unpleasant when you start off from 10% concentrate.

IMEX, the DPD method tends to fail if the level is approx > 5ppm in tube sample due colour suppression. (> More dilution required, not a problem if in the range 0-3 ppm of course. )

I didn't know that UK still used levels up to 200ppm av.Cl2.

@Brianp, Actually approx. 10pct (more typically 8-10% ) available chlorine (Sodium Hypochlorite solution) is a commonly traded product in many places. I guess it may depend on yr location. Followed by (very considerable) dilution for subsequent use.
(BTW Welcome to the forum ! )

Rgds / Charles.C

[rahul]

Dear Ms.Anju,

There is a titration procedure available to check the strength of chlorine. The chlorine which you purchase should be checked as per the procedure to confirm the chlorine strength. you can ask any friend of yours who is working in a lab for that. Normally, if you are buying liquid chlorine for ur use, the strength will be 8-10 %, and soild chlorine it is 65%. to check the concentration of chlorine, from 10 ppm, you can use chlorine test paper, and buy a standard chlorine test kit for checking concentration below it. also, to find out how much quantity of chlorine to be used, you can use the following formula-
Amt of water present in the tank x PPM required / Strength of chlorine x 10

Rahul

[cosmo]

From memory in a past life....
We measured both total and available chlorine
Available is what was available to kill bacterium
Total was the total amount, including what has been used and is bound by organic material.
In short we could have 12ppm total and 0ppm available (dirty water) We also found it was the total concentration that imparted the chlorine taste. The total level is what determined when the water was changed.

[Sujit]

Dear Caz,

Useful colorimetric methods, esp. the popular DPD one, but (I expect) less accurate than titration (which apparently also not that perfect [as per my link]). Maybe good enough for anju though if willing to buy the comparator.

Sadly, all these methods are a bit nose-hand unpleasant when you start off from 10% concentrate.

IMEX, the DPD method tends to fail if the level is approx > 5ppm in tube sample due colour suppression. (> More dilution required, not a problem if in the range 0-3 ppm of course. )

I didn't know that UK still used levels up to 200ppm av.Cl2.

@Brianp, Actually approx. 10pct (more typically 8-10% ) available chlorine (Sodium Hypochlorite solution) is a commonly traded product in many places. I guess it may depend on yr location. Followed by (very considerable) dilution for subsequent use.
(BTW Welcome to the forum ! )

Rgds / Charles.C

Dear Charles,

I have used DPD method for chlorine below < 5 ppm and was accepted by our Auditor's, Campden and Chorleywood. For higher range, DPD disc's are available.
To check percentage of granular NaoCl, titration method is there. It is difficult to get 65% in commercial sodium hypochlorite, as chlorine is volatile, but is close.

Regards
Sujit

[Tony-C]

I didn't know that UK still used levels up to 200ppm av.Cl2.

Rgds / Charles.C

Dosing at this level with Chlorine is a bit old hat especially as a fresh water rinse is needed afterwards. I believe more people are using something like Peracetic Acid or Ozone.

From Wikipedia:

Peracetic acid is an ideal antimicrobial agent due to its high oxidizing potential. It is broadly effective against microorganisms and is not deactivated by catalase and peroxidase, the enzymes that break down hydrogen peroxide. It also breaks down in food to safe and environmentally friendly residues (acetic acid and hydrogen peroxide), and therefore can be used in non-rinse applications. It can be used over a wide temperature range (0-40 °C), wide pH range (3.0-7.5), in clean-in-place (CIP) processes, in hard water conditions, and is not affected by protein residues.

Regards,

Tony

Edited by Tony-C, 27 August 2010 - 06:05 AM.