Aging of Sodium Hypochlorite solution

JohnDB

Active member

Equipment
M4500DT
Jun 9, 2018
319
46
28
NZ
One for the industrial chemists :)
I'm told that this stuff loses its effectiveness with time and other things. At supposedly 300 g/litre of sodium hypochlorite when fresh, the specific gravity is stated in the MSDS to be 1.15 to 1.20 @ 20 degC. If it loses effectiveness, does the SG reduce too? Just wondering if I weigh a litre of the stuff, and and based on that, how much I should dilute it to get a 5% solution for cleaning lichen off a steel roof. I bought 20 litres about 6 months ago, but there's nothing on the container to say when it was produced so it could be years old.

Other info from the MSDS:
Chemical Entity Proportion (%)
Water >60
Sodium Hypochlorite 10-30
Chlorine
SODIUM HYPOCHLORITE: Available chlorine, as chlorineTLV TWA: 0.5ppm, 1.5 mg/m3: STEL: 1 ppm,
2.9 mg/m3 ES Peak: 1 ppm, 3 mg/m3 CEL TWA: 2 mg/m3 (compare WEEL TWA) The odour threshold is
likely to be similar to that of chlorine, 0.3 ppm.

Thanks for any ideas!
 

mikester

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M59 TLB
Oct 21, 2017
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www.divergentstuff.ca
The answer is "it depends". If it's in the original sealed container it will last longer than something re-sealed with poor gaskets. What it reduces to depends on your environmental conditions.

I wouldn't worry about it based on your application.
 

Biker1mike

Well-known member

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B6200, Kubota 2030 Front Blade, King Cutter 60" finishing deck
Jan 11, 2022
561
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Gallatin, NY USA
Unopened and stored around room temperature it should be good for close to 2 years. Once opened it degrades quickly.
SPG will tell you very little.
300g/l is 30%. Dilute accordingly. 200ml to 1 liter is about 6 percent. close enough for cleaning
 

Biker1mike

Well-known member

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B6200, Kubota 2030 Front Blade, King Cutter 60" finishing deck
Jan 11, 2022
561
463
63
Gallatin, NY USA
If he uses it on the roof, will it kill the plants below when it washes off the roof?
At 5% it will act just like household bleach.
plant and grass kill will depend on how much water is used to rinse and contact time.
 
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Dave Ogren

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BX23S w/FEL &BH &60" Mowing Deck, 48" Dirty Dog Box Blade, 48" Tar River Tiller,
Feb 16, 2022
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79
Asheville, N. C.
That is the best stuff to open up drain lines.
Here it is only sold by plumbing supply houses so not available in the retail market, so very few know about it. If you use about 6 pounds a year it will keep your septic tank and rain lines in good shape longer.
Dave
 

JohnDB

Active member

Equipment
M4500DT
Jun 9, 2018
319
46
28
NZ
Thanks for your replies everyone. It's in the original container, cap has good seals, so I'll assume still full or near full strength.

I have used it previously similarly diluted for washing down walls pre-painting, lots of rinsing with fresh water, grass was unaffected.
 

hagrid

Well-known member

Equipment
K1600GTL, ZX-14R
Jun 11, 2018
499
429
63
Pittsburgh
That is the best stuff to open up drain lines.
Here it is only sold by plumbing supply houses so not available in the retail market, so very few know about it. If you use about 6 pounds a year it will keep your septic tank and rain lines in good shape longer.
Dave
Hypochlorite or hydroxide?