operating in a surge condition. The device shall initiate
automatic blower shutdown sequence when the blower is reduced to
surge volume as indicated by motor current draw and shall give
visual indication of reason for shutdown. An override shall be
provided as necessary for blower startup and shutdown.
d.
A system shall be provided to control blower overload by opening
and closing the inlet [butterfly valve] [inlet guide vanes on
single stage centrifugal blower] based upon the current draw of
the motor. The system shall monitor motor current input to a
suitably conditioned and set-point controller.
2.3.11.5
Vibration Monitoring
Vibration pick-ups shall be provided for motor and blower bearings.
Vibration monitoring system shall be provided on control panel.
Centrifugal blowers shall have radial and axial vibration monitoring.
Monitor shall consist of front panel and circuit board which shall include
switches for display of signal and alarm levels, LED indicators for
annunciation of OK and alarm status, calibration and alarm adjustments, and
connectors for output signals.
2.3.11.6
Control Logic
Control logic shall be provided to monitor dissolved oxygen level signals
and select the number and [inlet guide vane setting for single stage
centrifugal blowers] [rotation speed of positive displacement blowers] to
provide for sufficient air to maintain desired dissolved oxygen level in
aeration tank(s).
2.4
AIR DISTRIBUTION SYSTEM
A system, including piping, valves, and supports shall be provided to
distribute air from the blowers to the air diffusers. The system shall be
of adequate capacity for the intended purpose and shall be adjustable for
balancing of air distribution.
2.4.1
Air Main
The air main from the blowers to the air supply assemblies shall be as
indicated. Eccentric reducers shall be provided at each change in air main
diameter. The crown of the air main shall be maintained at the same
elevation for the full length of the tank. Fittings and valves shall be
provided as indicated. Air main piping 150 mm 6 inches in diameter and
larger shall be ductile iron or Schedule 40 steel pipe. Air main piping
less than 150 mm 6 inches in diameter shall be ductile iron or Schedule 40
galvanized steel pipe. Hangers and supports shall be provided as required
for a complete installation.
2.4.2
Removable Header Air Distribution System
**************************************************************************
NOTE: Delete inapplicable header types and
materials of construction.
**************************************************************************
Removable header air distribution systems shall be provided as indicated
and each shall consist of an air supply assembly, removable header
assembly, and supports. The system shall be compatible with the air main
SECTION 11375A
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