LEARNING OBJECTIVE: Identify safe maintenance procedures and precautions
that apply to water treatment equipment.
Properly maintained equipment within a water
treatment plant ensures smooth and efficient operation
of water treatment. It is not possible to provide detailed
instructions on the maintenance of each type of
equipment in a water treatment plant. Therefore, this
chapter covers general maintenance requirements and
safety procedures on some of the more common types
of water treatment. For specific and detailed
maintenance instructions, refer to the manufacturers
manual for the type and make of equipment at your
facility. In addition, this chapter provides information
regarding different types of water storage facilities and
the maintenance procedures applying to them.
LEARNING OBJECTIVE: Understand basic
operation and preventive maintenance of
Chlorinators are most often classified as direct
feed or solution feed; however, they are also classified
by the type of diaphragm used in controlling the
chlorine feed. A description of each follows:
Direct-feed machines operate without a water
pressure supply, as they feed the chlorine gas
directly to the flow to be treated
Solution-feed machines dissolve the gas in a
minor flow of water and inject the solution into
the flow to be treated. They require a water
pressure supply for operation.
The water diaphragm machine is always a
vacuum-type, solution-fed machine. The
frictionless, punctureproof water diaphragm is
The mechanical diaphragm machine may be
either a direct-feed or solution-feed pressure
type, or the solution-feed vacuum type only.
Direct-feed chlorinators are used chiefly as
emergency equipment and on small installations
where it is not possible to obtain a water supply
suitable for operating a solution-feed machine. They
cannot be used where the pressure of the water being
treated is more than 20 psi and are limited in the types
of semiautomatic or automatic controls that may be
used. Because of the chlorine always being under
pressure as a gas, direct-feed machines leak gas easily
to the atmosphere and cause corrosion on nearby
equipment and structures.
Direct-feed chlorinators require the same main-
tenance of gas-piping and gas-feeding mechanisms as
described for solution-type feeders. But direct-feed
chlorinators do not require maintenance of equipment
in contact with chlorine solutions, because there is no
Solution-feed chlorinators introduce chlorine gas
into the water supply by means of a chlorine solution.
This solution is usually formed by drawing chlorine
gas into the jet stream of water at the low-pressure
point of the injector mechanism of the chlorinator.
Two general types are used in waterworks: the
bubbling or pulsating reduced-pressure type and the
vacuum type. Because they keep the chlorine under a
partial vacuum, they cause fewer chlorine leaks than
pressure gas chlorinators and direct diffusers.
Chlorination equipment to feed chlorine gas or
hypochlorite solution is of three general types,
depending on methods of control as follows:
In the manually controlled type, equipment must
be started and stopped manually, and rate of feed
must be manually adjusted to rate of water flow.