TACMINA::Useful Information/Sodium Hypochlorite Injection Rate Quick Reference

Sodium Hypochlorite Injection Rate Quick Reference

Raw Water Flow Rate Criteria

Target: 1mg/L

Raw water flow rate		Sodium hypochlorite injection rate (mL/min) at target rate 1mg/L
Raw water flow rate		12% solution			10% solution			6% solution
m³/h	L/min	Raw liquid injection rate (mL/min)	Recomm. dilution ratio	Diluted liquid injection rate (mL/min)	Raw liquid injection rate (mL/min)	Recomm. dilution ratio	Diluted liquid injection rate (mL/min)	Raw liquid injection rate (mL/min)	Recomm. dilution ratio	Diluted liquid injection rate (mL/min)
1	17	0.14	100	13.9	0.17	100	16.7	0.28	100	27.8
1.2	20	0.17	100	16.7	0.20	100	20.0	0.33	50	16.7
2	33	0.28	100	27.8	0.33	50	16.7	0.56	50	27.8
3	50	0.42	50	20.8	0.50	50	25.0	0.83	20	16.7
5	83	0.69	20	13.9	0.83	20	16.7	1.4	20	27.8
6	100	0.83	20	16.7	1.0	20	20.0	1.7	10	16.7
10	167	1.4	20	27.8	1.7	10	16.7	2.8	10	27.8
12	200	1.7	10	16.7	2.0	10	20.0	3.3	5	16.7
15	250	2.1	10	20.8	2.5	10	25.0	4.2	5	20.8
18	300	2.5	10	25.0	3.0	10	30.0	5.0	5	25.0
20	333	2.8	10	27.8	3.3	5	16.7	5.6	5	27.8
30	500	4.2	5	20.8	5.0	5	25.0	8.3	2	16.7
48	800	6.7	2	13.3	8.0	2	16.0	13.3	2	26.7
50	833	6.9	2	13.9	8.3	2	16.7	13.9	2	27.8
60	1000	8.3	2	16.7	10.0	2	20.0	16.7	1	16.7
100	1667	13.9	2	27.8	16.7	1	16.7	27.8	1	27.8
120	2000	16.7	1	16.7	20.0	1	20.0	33.3	1	33.3
150	2500	20.8	1	20.8	25.0	1	25.0	41.7	1	41.7
180	3000	25.0	1	25.0	30.0	1	30.0	50.0	1	50.0
200	3333	27.8	1	27.8	33.3	1	33.3	55.6	1	55.6
300	5000	41.7	1	41.7	50.0	1	50.0	83.3	1	83.3
500	8333	69.4	1	69.4	83.3	1	83.3	138.9	1	138.9
600	10000	83.3	1	83.3	100.0	1	100.0	166.7	1	166.7

* Dilution ratio:
To prevent gas locking and to ensure uniform mixing, dilution ratios that ensure a flow rate as close as possible to 30 mL/min when the injection rate of the raw liquid falls below 15 mL/min are selected.
(Adjust the dilution ratio to on-site conditions such as tank capacity and replenishment cycle.)

Injection Rate Calculation Form

(Note) Points when Selecting the Pump

When the selected pump is used with the discharge amount set at its small amount, gas lock and other discharge defects are more likely to occur.
Use the pump with the discharge amount set as close as possible to 100% (at 70% or more on stroke length adjustment type pumps, or at 50% or more on number of strokes adjustment type pumps).
For this reason, select a model of pump having as small a maximum discharge amount as possible that exceeds the required injection amount.

In the Quick Guide/Injection Calculation Form, exclude the "./. specific gravity" calculation to bring the calculation in line with the actual on-site circumstances.

Raw Water Criteria

Amount of raw water : A m³
(amount of water accumulated in tank and auxiliary facilities)

Target concentration : B mg/L

Sodium hyphochlorite : C%

Condition: chlorine consumption : Zero

ϑCalculation Formula
Amount of injected sodium hypochlorite = 6.94 x A x B x 12/C mL
When the amount of water is 1m³ and target concentration is 1 mg/L
1 m³ = 1,000 L1 mg/L target
1 mg/L x 1,000 L = 1,000 mg = 1 g (amount of effective chlorine)
As sodium hypochlorite = concentration 12%, then 1 g x 100 ./. 12 = 8.33 g
As the specific gravity when the concentration of sodium hypochlorite is 12%,
then the volume becomes 6.94 mL

[Extra Information]
On our home page bulletin board, we were asked the following question:
"How much chlorine should be introduced as a countermeasure for Legionnaire's
disease to make the concentration of chlorine in a 10m³ tank 10 mg/L?"
As the amount of introduced chlorine in the above question is as follows:
10 m³ = 10,000 L10 mg/ target
the amount of required chlorine (not amount of reagent but effective component)
is as follows:
10 mg/L x 10,000 L = 100,000 mg = 100g
Here, let's assume that the reagent to introduce is sodium hypochlorite of
concentration 12%. Then, the required amount becomes as follows:
100 g x 100 ./. 12 = 833.3 g
As the specific gravity of the 12% concentration sodium hypochlorite is 1.2, and
then the volume becomes 694 mL.
The amount of water is not only the volume of the tank itself; an amount of water
for the filtering unit, inside the piping and entire other systems is required.

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