channel type and shall be fastened at each end to the tank wall near the
bottom, in the flow stream of the influent to the chlorine contact tank.
Control of hypochlorinator shall be by means of liquid level sensing probes
located in chlorine contact tank. The hypochlorinator assembly shall be
housed in a reinforced fiberglass or metal housing of at least 0.9 mm 20
gage metal and lined with 25 mm one inch minimum thickness insulation.
Housing shall have a removable cover for easy access. [Tape heater or
thermostatically controlled heat lamps or other method of space heating
shall be provided].
3.6
CHLORINATOR ASSEMBLY
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NOTE: Delete this paragraph and subparagraphs
thereto when chlorinator is not required.
Hypochlorinator should be specified for all plants
4.38 L/s 100,000 GPD capacity and below.
Chlorinator should be specified for all plants 6.57
L/s 150,000 GPD capacity and above. Between 4.38
and 6.57 L/s 100,000 and 150,000 GPD capacity either
is suitable. Selection should be made on basis of
existing station or base practices, local
availability, and comparative costs.
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3.6.1
General
Chlorinator shall receive chlorine gas from chlorine cylinders and water
from the water supply system and discharge chlorine solution through piping
to the diffuser located in the chlorine contact tank. Chlorinator assembly
shall include chlorinator, scale, chlorine gas manifold, flexible
connector, water piping, chlorine solution piping, vent tubing, vacuum
signal tubing, diffuser, and housing.
3.6.2
Chlorinator
Chlorinator shall be solution feed vacuum-type and comprise the following
parts: a pressure-regulating or vacuum-regulating valve, a flowmeter, a
vacuum relief or vacuum shut-off valve, a pressure relief valve, a check
valve, an injector or ejector, a gas filter, a chlorine pressure gage, a
chlorine supply indicator, water pressure gage, a water strainer and an
electric heater. The chlorinator shall be designed for
proportional-automatic control. Chlorinator shall be so designed that the
control mechanism is under a vacuum when the unit is in operation. The gas
shall be thoroughly mixed with water before it is discharged from the
injector. The chlorinator shall function accurately within four percent of
the set feed rate regardless of normal variations in the water pressure
operating the machine. In case of failure of the gas supply, the
chlorinator shall be protected against flooding by a ball check valve or
similar device and under no condition shall it be possible for water or
water vapor to enter into any dry gas lines or control parts. Chlorinator
shall have a capacity to provide a dosage rate of not less than 2 to 8 mg/l
over a flow range from [_____] to [_____] L/s gpd. All component parts of
the chlorinator exposed to chlorine gas or chlorine solution shall be of
materials resistant to chlorine. The pressure-reducing or
vacuum-regulating valve shall reduce the pressure of the chlorine gas to a
vacuum and maintain a constant flow within plus or minus 4 percent for any
given setting of rate of feed. The vacuum and pressure relief device shall
limit the vacuum within the chlorine feeding-machine and provide a suitable
SECTION 11375N
Page 111
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