Bulletin 5001
Sizing Guide

Chemical Injection Technologies
Technical Bulletin
SUPERIOR Gas Chlorinators
Sizing Guide

A wide variety of factors determine the exact amount of chlorine to be fed to produce a desired result in a given application . All gas chlorinators
operate over a wide range of flow rates and usually can be converted to higher or lower ranges very easily. The maximum flow rate of a gas
chlorinator is at least 20 times its minimum rate, with any capacity metering tube. The following definitions may be helpful to those who areunfamiliar with some of the basic terms used in chlorination and in water and wastes treatment:

DOSAGE: The amount of chlorine put into water or wastewater,

COMBINED CHLORINE RESIDUAL: That portion of theexpressed in parts per million (PPM) or Milligrams per Liter (Mg/L)of chlorine to water.

total chlorine residual which will react chemically and biologicallyas chloramine (Chloramine is the combination of chlorine andammonia). This form of chlorine is more volatile and does not reactas rapidly as free residual.

DEMAND: The amount of chlorine required to react with theorganic and inorganic substances and to kill the bacteria present
in the water being treated.
EFFLUENT: The liquid discharge of a treatment plant or of apiece of equipment or tank within the plant.

TOTAL CHLORINE RESIDUAL: The amount of chlorine

B.O.D.: Biochemical Oxygen Demand; the required amount ofoxygen necessary for the chemical and biological oxidation ofwaterborne substances in a specific time, under specificconditions.

remaining, after a specified contact period, that is still available forreaction. Basically, this is the amount of chlorine in excess of theDEMAND.

PPD OR GMS/HR: Pounds Per Day, refers to the pounds ofchlorine per day and/or Grams Per Hour, refers to the grams ofchlorine per hour, required to do a specific job.

FREE CHLORINE RESIDUAL: That portion of the total

PPM OR Mg/L: Parts Per Million, pounds of chlorine perchlorine residual which will react chemically and biologically as
hypochlorous acid or hypochlorite ion. Generally, this is the mostpotent form of residual and reacts most rapidly.

million pounds of water; or Milligrams Per Liter, Milligrams ofchlorine per liter of water. PPM and Mg/L are numerically
identically measurements.

CALCULATING THE CHLORINATOR SIZE/CAPACITY
Chlorinator size should be based on the maximum expected flow rate of the water being treated at any time. Use Gallons Per Minute (G.P.M.),
Cubic Meters Per Hour (M3/hr.), or Liters Per Second (L/sec.) of water flow rather than daily total or an average. The basic formulas forcalculating chlorine feed rate are as follows:

U.S. (ENGLISH)METRIC:

PPD = GPM x 0.012 x Dosage (PPM)

GMS/HR. = M3/hr. (water) x Dosage (Mg/L)

PPD = IMPERIAL GPM x 0.015 x Dosage (PPM)

GMS/HR. = L/sec. (liters/sec. water) x 3.6 x Dosage (Mg/L)

EXAMPLEA potable water treatment plant is operating at a maximum water flow rate of 2,000 gallons per minute. Chlorine demand is relatively low anda chlorine dosage rate of 1.9 PPM is needed to maintain the required chlorine residual. Following is the sizing calculation:
PPD CHLORINE = GPM x 0.012 x PPM = 2,000 x 0.012 x 1.9 = 48
Generally, it is desired to have a safety factor of 2 x required feed rate, so a 100 PPD SUPERIOR Gas Chlorinator would be specified.
(continued)

Pub. No. 1293-2

Copyright © 1993, Chemical Injection Technologies, Inc

Printed in U.S.A.

Page 2DOSAGE GUIDE† The dosage rates shown below in PPM or Mg/L are for average conditions, which may vary depending on location.

TYPICAL DOSAGE RATES IN PPM OR Mg/L†

CHLORINATION TREATMENT FOR

WATER TREATMENTWASTEWATER TREATMENTDISINFECTION

1-10 Free Residual
1-5 Combined Residual

TASTE

1-3

ODOR

1-3

ALGAE

3-5

SLIME

3-5

IRON & SULFUR BACTERIA

1-10 varying with the amount of bacteria to be controlledCOLOR REMOVAL

Dosage depends on type and extent of color removal desired. May varyfrom 1 to 500 PPM dosage rate.

IRON PRECIPITATION

0.64 times Fe content

MANGANESE PRECIPITATION

1.3 times Mn content

HYDROGEN SULFIDE - Taste & Odor Control
Destruction

2 times H2S content
8.4 time H2S content

COOLING WATER

1-10

CHILLING WATER

5-25

WASHDOWN WATER

25-50

DISINFECTION:
Sand Filter Effluent
Activated Sludge Effluent
Trickling Filter Effluent
Chemical Precipitation Effluent
Raw Sewage
Settled Sewage
Septic Raw Sewage
Septic Settled Sewage1-5
2-10
3-10
3-10
5-20
5-25
10-25
10-40

B.O.D. REDUCTION:
Activated Sludge Effluent
Raw Screened Sewage

5-15
5-15

ODOR CONTROL:Up Sewer
Plant Influent
Trickling Filter Effluent
Digester Supernatent

2-20
2-20
2-5
200-300

TRICKLING FILTER PONDING

5-20

TRICKLING FILTER FLIES

3-10

CYANIDE:
Reduction to Cyanate
Complete Destruction

2.0 times cyanide content
8.4 times cyanide content

Pub. No. 1293-2

Copyright © 1993, Chemical Injection Technologies, Inc

Printed in U.S.A.