13.
Electric power characteristics for motors.
14. Whether automatic operation of air lift pumps
should be required.
15. Wind load and ice load for rotating sludge
collector.
16. Organic loading (5-day BOD) if other than that
given in the text.
17. Total suspended solids if other than given in
the text.
18. Size of hypochlorite mixing tank if larger
capacity than 113.4 L 30 gallons is needed.
19. Size of hypochlorite solution tank if larger
capacity than 208 L 55 gallons is needed.
20. Whether, for extended aeration type plant,
eventual conversion to step aeration type is
anticipated.
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a.
Design: The mechanism shall be designed to have a minimum
continuous output torque rating of 2710 joules 2,000 foot pounds
and to rotate at a constant speed to produce a peripheral speed of
31 to 51 mm per second 6 to 10 fpm. The rotating mechanism and
its component parts shall be designed, with a minimum factor of
safety of 4, to withstand all structural and mechanical stresses
brought about by the following loadings: continuous output rated
torque load, dead load, wind load of [_____], [ice load of
[_____]], and a live load on the access bridge of 2.4 kPa 50 psf.
Stresses developed under the aforementioned loads shall not exceed
the allowable stresses conforming to AISC 335. Deflection of
support bridge under maximum load shall not exceed 1/360 of the
span.
b.
Drive Assembly: Drive assembly shall include motor, gearing,
bearings, main bearing assembly, and chain and belt drives. Drive
shall be either a single worm gear reduction unit, a double worm
gear reduction unit, or a worm and spur gear reduction unit,
driven by an electric motor through a speed reducer or by an
electric gearmotor. Drive motor shall be close-coupled to or on
the input shaft of the gear reduction unit, except that roller
chain drives or V-belt drives may be used between the drive motor
and gear reduction unit. V-belt drives will not be permitted
directly on the center shaft which rotates the collector assembly.
The equipment design shall be such that all gears run in oil and
all bearings shall be oil or grease lubricated. Gear cases shall
be equipped with oil fill port, oil drain line and an oil level
indicator pipe. The design of each drive assembly shall be such
as to permit sustained operation at the continuous output torque
rating without excessive wear and to develop twice the continuous
output torque rating without damage to or failure of the drive
assembly components.
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SECTION 11375N
Page 54
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