available torque, 360-degree rotation with equal performance in either
direction of rotation. Casing shall be close-grain cast iron or aluminum
alloy of adequate strength and rigidity to withstand all loads imposed on
it from the operation of the comminutor and drive assembly. The casing
shall have the manufacturer's recommended concave semi-circular screen of
stainless steel attached to it.
2.6.2
Rotating Disc or Conical Type
The rotating disc or conical type comminutor shall include a stationary
grid frame cutter-comb support with cutter-combs, rotating cutter
plate/screen with adjustable teeth, and a drive assembly. The cutter
plates shall be fixed and keyed to the center drive shaft permitting only
one cutter tooth and a cutter comb to be engaged at one time for load power
saving. The frame, grid, and discs shall be of close-grained cast iron or
aluminum alloy. The conical screen shall be constructed of the
manufacturer's recommended stainless steel.
2.6.3
Oscillating Type
The oscillating type comminutor shall include a stationary semi-circular
screen, a stationary cutter bar mounted on a support casing, an oscillating
cutter bar, and a drive assembly. Cutter bars shall be adjustable and
readily removable for inspection, sharpening, or replacement. The
oscillation shall be actuated by mechanical conversion of the driver
rotation. Casing shall be close-grain cast iron or aluminum alloy of
adequate strength and rigidity to withstand all loads imposed on it from
the operation of the comminutor and drive assembly. The casing shall have
the manufacturer's recommended semi-circular screen of stainless steel
attached to it.
2.7
MOTOR CONTROLLER
The control panel shall be mounted where indicated. The motor controller
shall be rated as indicated and conform to NEMA ICS 2. The control system
shall include an automatic motor starter reset for power failure protection
[and an automatic drive motor reversal with time delay for jamming
protection in the event of hard particle entrapment in the comminutor
cutters]. The reversing controller shall sense jams and reverse motor
rotation as often as necessary, and will continue to operate providing
partial sweeps on the comminutor arm, with no danger of motor damage. An
audible and visual alarm system shall be provided to signal both field
operator and area office in case of malfunction.
2.8
DESIGN
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NOTE: Refer to TM 5-814-3 for design requirements.
The following information should be shown on the
project drawings covered by the specification as
appropriate:
a. Size and type of channel pipe or joint in which
comminutor is to be mounted. Specify whether
comminutor access openings are located within pits
or manholes.
b. Minimum, average, and maximum sewage flows. The
maximum rating of a comminutor should be made with
SECTION 11331
Page 8
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