2.2.6.5
Check Valves
Check valves shall be double door type, flange or wafer style, capable of
handling 862 kPa 125 psig cold working pressure (CWP) with cast iron body
and aluminum bronze internal parts, low torque spring for low pressure air
service. Seal material shall be capable of handling temperatures from -29
to plus 121 degrees C -20 to plus 250 degrees F with tight shutoff
capability.
2.2.7
Expansion Couplings
Expansion couplings for nonsubmerged locations in the aeration system shall
be constructed of materials suitable for temperatures up to 121 degrees C
250 degrees F and pressures up to 103 kPa 15 psig. Couplings shall be of
the filled arch type. Back-up or retaining rings shall be provided as
required. Couplings shall be yoked to transmit tension loadings.
Compressive and lateral movement of the joint shall not be impaired by the
yoke system.
2.3
AIR-SUPPLY EQUIPMENT
The air-supply shall consist of [multi-stage] [_____] [centrifugal] [and]
[or] [positive displacement] air blowers and drive units with filters,
controls, and appurtenances as indicated or specified.
2.3.1
Centrifugal Blowers
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NOTE: Blowers should be identified on the drawings
by type and operating characteristics.
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2.3.1.1
Blowers shall be [multistage] [single stage] centrifugal, oil-free types
designed for continuous duty with [closed backward-bladed] [open
shown.
2.3.1.2
Casing
Centrifugal blowers shall be of modular design with the casing either
vertically or horizontally split and with the required number of
compression stages to comply with the specified operating requirements.
Horizontally split casings shall be machined at the split to be tight
without a gasket. Vertically split casings shall consist of rigid cast
iron sections held securely between cast iron inlet and outlet heads by
steel tie rods. Tapped and plugged drains shall be provided at the lowest
points of the casing. Inlet and discharge connections shall be ASME B16.1
[Class 125] [125 pound] [_____] drilled and tapped flanges and shall be an
integral part of the head. Casing shall have lifting eyes capable of
supporting blower.
2.3.1.3
Impellers
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NOTE: Other impeller materials, such as steel, are
available. Consult with various manufacturers for
recommendations.
SECTION 11375A
Page 12