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Formulas and Conversions

Formulas and Conversions

Required capacity of Gas Chlorinator:
GPM * 0.012 * PPM = PPD
Required capacity of 12.5% Sodium Hypochlorite:
GPM * 0.012 * PPM = GPD "GPD/24 = GPH"
Gas to 12.5% Sodium Hypochlorite Approximation:
GPD = PPD

Where: (scroll down to see formula example)

  • GPM=Maximum quantity of water to be treated in gallons-per-minute
  • PPM=Maximum desired chlorine concentration of the treated water in parts-per-million
  • PPD=Minimum amount of chlorine required in pounds-per-day
  • GPD=Minimum amount of 12.5% sodium hypochlorite required in gallons-per-day

Conversion Factors

1 lb = 0.453 kg
1 kg = 2.2 lb
1 oz = 30 g
1 g = 0.0335 oz
1 qt = 0.95 L
1 L = 1.06 qt
1 gal = 3.8L
1 L = 0.26 gal
°F = (9/5*°C) +32
°C = (°F -32)*(5/9)
1 ft = 30cm
1 cm = 0.04 ft
1 yd = 0.9m
1 m = 1.1 yd
1 PPM = 1 g/cm3 = 1 mg/L
1 GPM = 2.28*10-3 ft3 /second

Formula Example

GPM * 0.012 * PPM = PPD
This formula calculates a required size chlorinator in pounds of chlorine per day (PPD), given the Gallons Per Minute (GPM) solution flow and the Parts Per Million (PPM) chlorine dosage.

For example, to calculate the PPD of chlorine feed required to treat 1,000,000 gallons-per-day (or 694.4 GPM) to a final concentration of 1 PPM: 694.4 * 0.012 * 1 = 8.33 PPD

In this case a 10 PPD Hydro Instruments Model 500 would be the minimum sized chlorinator to be used for this water treatment application.