Calculating Residual Chlorine Level From 14% Sodium Hypochlorite

[JamesDUK]

Hi,

I'm looking to calculate the amount of 14% NaOCl solution to dose a water flow rate of 2000 m3/hr and leave 1 mg/l of residual Chlorine.

I assumed it was a simple calc, 1 mg/l = 1 ppm, so 2 litres needed an hour. At 14% that 2/.14 = 14.3 l/hr, was my thought.

However a colleague told me I need to be look at mass.

So as the 14% NaOCl has an SG of 1.2, then my 14.3 l/hr = 17.16 kg/hr and only (14.3-2) 12.3 l/hr of that is water, so 12.3 kg./hr of water leaving 4.86 kg/hr of NaoCl.

Which will actually equate to 2.43 mg/l of residual chlorine.

Is that correct, do I actually need a lot less than I'm thinking?

Thanks in advance from a mech eng!

 

[bimr]

Commercial grade 12.5% sodium hypochlorite has typical properties of 10.4% chlorine and is 10.8% sodium hypochlorite with a S.G. of 1.16.

The chlorine residual is the amount of chlorine remaining after the chlorine has reacted with whatever is in the water. I would start feeding 2 mg/l to obtain the 1 mg/l residual. Then you may reduce the 2 mg/l to optimize.

1 mg/L * 2000 m3/hr * 24 = 48 kg/day

48kg/day / 10.4% = 461.5 kg day Sodium Hypochlorite