2.3.8
Water Circulation Pumps
Water circulation pumps shall be single stage, centrifugal, enclosed
impeller, electrically driven, non-overloading type with integrally mounted
motor. The pump shall be connected to the motor with a flexible coupling.
Motor shall conform to NEMA MG 1 for operation on [_____] volts ac, [_____]
phase, 60 Hz and shall be equipped with thermal overload protector with
manual reset. Motor frame shall be [open] [dripproof] [totally enclosed]
[explosion-proof] type.
2.3.8.1
Heat Exchanger Water Circulation Pump
The heat exchanger water circulation pump shall be mounted in line with the
heat exchanger package. Pump rating shall be determined by the heat
exchanger manufacturer as required to provide turbulent flow across the
sludge tubes.
2.3.8.2
Building Heat Water Circulation
**************************************************************************
NOTE: Delete paragraph Building Heat Water
Circulation if system is not used for building heat.
Coordinate criteria with building heating system
specification.
**************************************************************************
The building heat water circulation pump shall be rated at [_____] L/second
gpm and [_____] mm feet TDH.
2.4
MECHANICAL SLUDGE MIXING SYSTEM
**************************************************************************
NOTE: For projects with single-stage
sludge-digestion, delete "primary" and include
reference to bottom 1/10 of contents. For projects
with two-stage sludge digestion, include "primary"
and delete reference to bottom 1/10 of contents.
**************************************************************************
Electric motor driven mechanical mixers shall be provided in each [primary]
[_____] digester, each capable of producing a flow of [____] L/second gpm
of sludge. The combined action of all the mixers shall effectively
circulate all [except the bottom 1/10] of the digester contents. Mixers
shall be suitable for mixing sludge on a continuous basis.
2.4.1
Motor
The electric drive motor shall be mounted on the outside of the digester on
the [gear reduction unit] [or] [mixer bearing support.] Motors shall be in
accordance with NEMA MG 1 and shall be of explosion-proof design for
operation near digester gas. Motor shall be sized for and shall not
overload under the intended conditions. Motor shall operate on [_____]
volts ac, [3] [_____] phase, 60 Hz and shall be provided with thermal
overload protection.
2.4.2
Speed Reducer
A unit shall be provided for the mechanical reduction of speed while
SECTION 11380
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