UFC 3-240-13FN
25 May 2005
sidestream using a three-valve bypass configuration. Feeders may have funnels or
screw caps. The overall volume of a water treatment system should be considered
when determining the proper size of a pot feeder. A 3.78-liter (1-gallon) pot feeder on a
75,700-liter (20,000-gallon) closed system can work, but is not practical. A larger 18.9-
liter (5-gallon) pot feeder is more practical. Some pot feeders are designed to serve a
dual purpose as a filter.
Figure 7-1. Chemical Pot Feeder
7-2.1.2
Dry Chemical Feeders. Small cooling towers often require a dry,
granular, or pelletized product for control of scale, corrosion, or microbiological
organisms. The dry chemical can be placed in a plastic mesh bag and hung in the
cooling tower sump or put into a plastic container having small holes through which a
stream of water can pass. Small cooling towers can be shock-fed with a liquid chemical
agent, such as a biocide. This practice is not efficient and may be ineffective. The
manual handling of biocides also raises safety concerns. A liquid chemical feed system
may be more effective.
7-2.2
Automatic Chemical Feed with Manual Preparation. This type of feed
system is commonly found on steam boilers for which an operator must physically
prepare a chemical mixture specific for that boiler operation. After preparation, the
chemical mixture is automatically fed on demand using a chemical pump that is
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