Disinfection of Pipelines - Disinfection of Pipelines and Storage Facilities Field Guide - page 46

Example 1. Using the continuous feed method to disin-
fect 1,000 ft of 6-in. pipe, liquid chlorine is injected with suc-
tion provided by a gas-powered, 20-gpm pump. No other water
is being used to fill the pipeline. What is the chlorinator setting
to result in 25 mg/L dosage? What is the total amount of chlo-
rine needed for the job?
Use the checklist to ensure all of the information is collected.

❑ The pipeline diameter and length.

6-in. diameter and 1,000-ft length

❑ Valves, hydrants, tees, and other appurtenances.

No valves or hydrants in job description

❑ Volume of chlorination water to disinfect pipeline.

From Table 3-6, 6-in. pipe contains 1.47 gal/ft, so
1,000 ft contains 1,470 gal. At 20 gal/min fill rate, the
procedure will take about 74 min.

❑ Amount of chlorine needed to complete the disinfection

procedure.
From Table 3-9a, 500 ft of 6-in. pipe requires 0.15 lb,
so for 1,000 ft, 0.3 lb is needed.

Complete the procedure by matching (calculating using
c3-1) the liquid chlorine feed rate with the pipeline fill rate
(20 gpm in this case).

☞

Liquid chlorine
feed rate (lb/day)

Water fill rate
(gpm) total

=

0.3 ×

lb/day = 20 gpm 0.3 = 6 lb/day feed rate to

provide 25 mg/L dosage

×

Example 2. Using the continuous feed method to disin-
fect 500 m of 200-mm pipe, 1 percent sodium hypochlorite solu-
tion is injected into water filling the pipeline. The pipeline is
filled at 3 L/sec. What is the sodium hypochlorite solution feed
rate to result in 25 mg/L dosage? What is the total amount of
chlorine needed for the job?