Figure 4-21.Fire hydrant installation.
Hypochlorite solution is usually applied by
measuring pumps, gravity-feed mechanisms, or
portable pipe disinfecting units.
When applying disinfectants, use the following
Before adding disinfectant, flush the section
thoroughly with water until dirt and mud are removed.
A velocity of at least 3 feet per second is required for
Stop all branches and other openings with plugs
or heads properly braced to prevent blowouts.
Disinfect the water mains in sections and feed
the disinfecting agent through a tap or hydrant at the end
of each section. When a portable gas chlorinator or
hypochlorinator is available, feed the discharge from the
chlorinator into an auxiliary waterline leading to one of
the hydrants or taps.
Bleed the air from the line at high points and
crowns. Add the predetermined chlorine dosage as the