glass and drain fittings shall also be provided. The thermal
rating of the gear reducer shall exceed the design load. If this
is not the case, then proper cooling shall be provided.
b.
Lubricating pumps shall be removable for maintenance without
disassembly of the drive and/or removal of the motor. Either a
low pressure or low oil level switch shall be provided to shut off
the unit in the event of insufficient lubrication.
2.4.3.6
Power transmission from the motor to the gear reduction system shall be
supplied by a nonlubricated coupling, direct driven. Couplings shall be
the manufacturer's standard and shall be selected to provide a minimum
service factor of 2.0.
2.4.4
Mounting
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NOTE: To maintain the water level within the
recommended range it is very important that the
effluent weir be sized properly and be manually
adjustable.
Verify immersion depth with potential manufacturers.
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A [structural bridge of steel conforming to ASTM A 36/A 36M] [concrete
bridge] and support assembly designed to mount each aeration unit shall be
constructed as indicated. The bridge assembly shall be structurally
anchored to the basin walls. To ensure the most efficient operation of the
aeration system, the aerator shall be mounted with the top of the impeller
blades [50] [_____] mm [2] [_____] inches above the minimum water surface
elevation. The blades shall not be submerged more than [200] [_____] mm
[8] [_____] inches at the maximum water surface elevation.
2.4.5
Protective Covering
The manufacturer shall supply an [ultraviolet light protected fiberglass]
[_____] cover for each aeration unit. The cover shall be designed to
protect all adjacent structures from splashing caused by the unit. The
cover shall be mounted independent of the aeration equipment and be
installed in accordance with the manufacturer's requirements.
2.5
SUBMERGED TURBINE DRAFT TUBE AERATORS
The submerged turbine draft tube aeration system shall be furnished and
installed as indicated. The unit shall be complete and include blowers,
drive unit, turbine aerator unit and supports, draft tube assembly, and all
appurtenances necessary for the proper operation of the equipment. The
aerators shall be designed for continuous operation.
2.5.1
Impeller Shaft
The shaft shall be constructed of [carbon steel] [_____] and shall be sized
to withstand all torque loads and bending moments produced by operation of
the system. The shaft and bearing assembly shall be designed to allow
operation below 80 percent of its natural frequency without the use of
stabilizing devices. The shaft shall be so constructed that its deflection
SECTION 11391
Page 20
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