Liquid chlorine date of manufacture

emac

Well-known member
May 24, 2017
60
abbeville, SC
My pool runs year round. I went to buy some liquid chlorine today as mine was getting pretty old. Lowes and walmart are about the only two places nearby that sell high concentration. I went to Lowes and their dates were December 2022! Walmart had some dated May 26, 2023 for $2 cheaper per gallon. It makes a big difference, as my 6 month old chlorine was getting worthless. Check those dates!
 
The Office Yes GIF
 
See this this page for half life info.


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I finally got around to making a spreadsheet using the rate constants from this link (same as this link) plus some fitting and fudge factors to be consistent with Odyssey Manufacturing half-life and this paper so I'm showing decomposition rates for 12.5% (trade %) chlorinating liquid below over time vs. temperature.

Degradation of 12.5% Chlorinating Liquid
TIME100ºF95ºF90ºF85ºF80ºF75ºF70ºF
Initial12.50%12.50%12.50%12.50%12.50%12.50%12.50%
1 day11.92%12.10%12.22%12.31%12.37%12.41%12.44%
2 days11.42%11.74%11.97%12.13%12.25%12.33%12.39%
3 days10.99%11.41%11.73%11.96%12.13%12.25%12.33%
4 days10.61%11.12%11.51%11.80%12.02%12.17%12.28%
5 days10.28%10.85%11.30%11.65%11.91%12.09%12.22%
6 days9.98%10.60%11.10%11.50%11.80%12.02%12.17%
1 week9.71%10.37%10.92%11.36%11.69%11.94%12.12%
2 weeks8.33%9.13%9.87%10.51%11.04%11.46%11.78%
3 weeks7.45%8.29%9.10%9.85%10.50%11.04%11.47%
1 month6.68%7.51%8.36%9.18%9.93%10.57%11.11%
2 months5.14%5.90%6.73%7.60%8.49%9.33%10.10%
3 months4.27%4.95%5.72%6.57%7.48%8.40%9.28%
4 months3.79%4.42%5.13%5.93%6.81%7.74%8.67%
5 months3.47%4.05%4.72%5.48%6.33%7.24%8.18%
6 months3.23%3.78%4.41%5.13%5.95%6.84%7.78%

The following shows the decomposition rates for 8.25% (weight % sodium hypochlorite) bleach below over time vs. temperature.

Degradation of 8.25% Bleach
TIME100ºF95ºF90ºF85ºF80ºF75ºF70ºF
Initial8.25%8.25%8.25%8.25%8.25%8.25%8.25%
1 day8.10%8.15%8.18%8.20%8.22%8.23%8.24%
2 days7.96%8.05%8.11%8.15%8.19%8.21%8.22%
3 days7.83%7.95%8.04%8.11%8.15%8.18%8.21%
4 days7.70%7.86%7.98%8.06%8.12%8.16%8.19%
5 days7.58%7.77%7.91%8.02%8.09%8.14%8.18%
6 days7.47%7.69%7.85%7.97%8.06%8.12%8.16%
1 week7.36%7.61%7.79%7.93%8.03%8.10%8.15%
2 weeks6.75%7.11%7.42%7.65%7.83%7.96%8.05%
3 weeks6.28%6.72%7.10%7.41%7.65%7.83%7.96%
1 month5.82%6.31%6.75%7.13%7.43%7.67%7.85%
2 months4.77%5.32%5.86%6.37%6.82%7.20%7.50%
3 months4.10%4.64%5.22%5.78%6.32%6.79%7.19%
4 months3.70%4.22%4.79%5.37%5.94%6.46%6.92%
5 months3.41%3.92%4.46%5.04%5.63%6.19%6.69%
6 months3.20%3.68%4.21%4.78%5.37%5.95%6.48%

Since day and night temperatures are not the same, one must use a special average that accounts for the non-linearity of degradation as a function of temperature. As derived in this post, the following table shows how you can take a known temperature difference between day and night and add an effective temperature adder to the nighttime temperature to get the effective temperature to look up in the above tables.

TempDiff . EffAvgTempAdder
..... 5 ............ 2.7
... 10 ............ 5.8
... 15 ............ 9.4
... 20 .......... 13.2
... 25 .......... 17.3
... 30 .......... 21.7
... 35 .......... 26.2
... 40 .......... 30.9

:cheers:
 
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