vent to the outside atmosphere for the escape of any chlorine gas release
through improper operation of the equipment. A vacuum shut-off valve may
be substituted for the vacuum relief which will seal off the chlorinator
when excessive vacuum is present. The flowmeter shall be a metering device
for measuring the flow of chlorine gas in pounds per 24 hours over a range
of not less than 10 to 1 maximum feed and shall be mounted on the face of
the chlorinator. The injector or ejector shall receive all chlorine and
make-up water and discharge the resulting solution to the point of an
application. A check valve that will prevent water backing into the
injector suction line shall be provided. The vacuum regulator valve shall
automatically close when ejector water supply or ejector vacuum is lost.
Chlorine pressure gage shall be of the diaphragm type, and shall be made of
corrosion-resisting material. The gage shall indicate accurately the
pressure of chlorine gas as supplied from the cylinder. Chlorine supply
indicator shall be supplied with the unit to show whether chlorine is
available or exhausted. The proportional-automatic control device shall be
actuated by a pressure differential or a signal from the primary element
and shall be so transmitted or converted as to vary the rate of chlorine
feed in proportion to the rate of flow over the entire range of the
chlorine meter in the chlorine feeding machine. The equipment shall be
actuated by the flowmeter. Chlorinator shall be floor, panel- or
wall-mounted. Floor-mounted and panel-mounted units shall have necessary
components enclosed in a panel or cabinet and shall be self-supporting.
Wall-mounted unit shall contain all necessary components and shall be
capable of firm attachment to a wall or partition.
3.7
COMMINUTOR AND BAR SCREEN UNIT
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NOTE: Delete paragraph and subparagraphs when
comminutor is not required for plant. For plants of
1.09 L/s 25,000 GPD capacity and below, the
comminutor and bar screen unit may be omitted, and
in lieu thereof, a screening basket provided in the
aeration tank. For installations in which all
sewage has passed through a comminutor and bar
screen upstream of the plant, a comminutor and bar
screen unit need not be provided as a part of the
plant equipment.
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3.7.1
General
The comminutor and bar screen assembly shall be complete and self-contained
and so arranged that whenever the comminutor is not operating, all sewage
shall be diverted automatically through the bar screen before it enters the
plant, and whenever the comminutor is operating, all sewage is directed
through the comminutor.
3.7.2
Comminutor
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NOTE: Insert flow rates as derived from NAVFAC
DM-5, Figure 10-1.
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The comminutor shall be rotating type and shall include a rotating slotted
drum that functions as a screen and a support for the rotating cutters, a
casing that supports the stationary cutters, and a drive assembly. The
SECTION 11375N
Page 112
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