English Instructor Manual (PDF) - Metric Version - National ...

Chapter 9 – Chemical Feed and Control
Handbook: Pages 99-116
Suggested Time:
PowerPoint Slides:
Materials:
30 minutes
Chapter 9 Slides
Sample chemical feeder pump
Objectives: At the end of this lesson, the student will be able to:
1. List the methods by which chemicals can be added to pool/spa water
2. Explain the difference between the various types of chemical feeders
3. Explain the advantages of automated chemical feeders
Leading Questions:
What are several ways that chemicals can be added to the pool?
What are the advantages and disadvantages of each?
What are some safety precautions that should be observed when handling chemicals?
Key Points: Discuss the various aspects of chemical feeders. These include:
Chemical feeders provide effi cient addition of chemicals to water with minimal handling
of the chemicals
Common feeders include erosion (tablets), metering (liquid), or injection (gasses)
Feeders can be manually operated or electronically controlled
Feeders are a must for chemicals added on a daily basis, e.g. chlorines and acids
Key Points: Discuss how to add chemicals to the water. Emphasize that, in most cases,
chemicals should be added in small amounts over a long period of time. Exceptions include
superchlorination and specialty chemicals, such as algaecides. Explain that feeding chemicals in
the pool may be done in several ways. These include:
Mechanical feeders. These include peristaltic, diaphragm, and piston pumps.
Dry chemical feeders. These include erosion feeders and pressure-to-vacuum feeders.
Gas feed systems. These include chlorine gas feeders and CO 2
feeders.
Ozone generators. These include corona discharge and ultraviolet ozonators.
Chlorine generators. These include in-line generators and brine-bank generators.
Manually. This includes manually over the main drain, manually into a skimmer, and
broadcast directly across the pool
Key Points: Discuss feeder automation. Include a brief discussion of:
Advantages of automated control systems related to proportional feed feature and
remote alarm options
Types of chemical sensors: pH probes, ORP probes and amperometric probes
Probe location and probe cleaning
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