has replaced the selected lead blower in operation.
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NOTE: Delete first sentence or second sentence in
item (c) depending on whether chlorinator or
hypochlorinator is specified. 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 L/s and 6.57 L/s
100,000 GPD 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.
**************************************************************************
c.
[Chlorinator shall be controlled by the flow meter and shall
start, stop, and proportionally regulate the dosage in response to
signals there from]. [Hypochlorinator shall start and stop in
response to signals from liquid level sensing probes.]
d.
Thermostat shall automatically place into operation equipment
automatically taken out of service by the 7-day timer when the
outside air temperature drops below 0 degrees C 32 degrees F or
any other predetermined temperature setting.
e.
A percentage timer shall automatically control sludge transfer
pump, scum transfer pump, and supernatant return pump.
f.
Froth control system pump shall be suitably interlocked with
blowers so as to automatically start and stop in parallel with the
blowers.
2.13.3
Electrical Control System Enclosure
**************************************************************************
NOTE: Specify outdoor type enclosure except when
enclosure will be located in a building.
**************************************************************************
**************************************************************************
NOTE: Use first optional wording in last sentence
for outdoor enclosure and second optional working
for indoor enclosure.
**************************************************************************
Enclosure shall be [a free-standing, floor-mounted type indoor unit] [an
outdoor unit with support legs] and shall be constructed of sheet steel.
Screened ventilating openings shall be installed in the enclosure.
Enclosure shall have rubber-gasketed doors provided with continuous piano
hinge and cylinder locking type door latches. Each door shall be equipped
with positive locking device. A copy of the external wiring connections
and a circuit breaker index print shall be secured to the inside of door.
Control panel shall be mounted on legs formed from steel or angle iron
welded to the bottom of the enclosure. The legs shall have bottom plates
drilled with holes for securing the panel to [tank platform or concrete
pad] [concrete floor].
SECTION 11375N
Page 71
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