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 manufacturer's 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.
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 an advantage,
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 contact.
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.Continue Reading