control equipment and with a split or solid cast-iron or steel cover plate.
Each pump shall be directly connected by an approved flexible coupling to
a vertical electric motor having a continuous oiling device or packed
bearings sealed against dirt and moisture. Motors shall be totally
enclosed, fan-cooled of sizes as indicated and each shall be equipped with
an across-the-line magnetic controller in a NEMA 250, Type [1] [4]
enclosure. Each pump shall be fitted with a high grade thrust bearing
mounted above the floor. Each shaft shall have an alignment bearing at
each end, and the suction inlet shall be between 75 and 150 mm 3 and 6
inches above the sump bottom. The suction side of each pump shall have a
strainer of ample capacity. A float switch assembly, with the switch
completely enclosed in a NEMA 250, Type [1] [4] enclosure, shall start and
stop each motor at predetermined water levels. Duplex pumps shall be
equipped with an automatic alternator to change the lead operation from one
pump to the other, and for starting the second pump if the flow exceeds the
capacity of the first pump. The discharge line from each pump shall be
provided with a union or flange, a nonclog swing check valve, and a stop
valve in an accessible location near the pump.
2.15.2
Circulating Pumps
Domestic hot water circulating pumps shall be electrically driven, single
stage, centrifugal, mechanical seals, suitable for the intended service.
Pump capacities, efficiencies, motor sizes, speeds, and impeller types
shall be as shown. Pump and motor shall be [integrally mounted on a
cast-iron or steel subbase,] [close-coupled with an overhung impeller,]
[or] [supported by the piping on which it is installed]. The shaft shall
be one piece, heat-treated, corrosion-resisting steel with impeller and
smooth surfaced housing of bronze. Motor shall be totally enclosed,
fan-cooled and shall have sufficient wattage horsepower for the service
required. Pump shall be hydraulically balanced. Each pump motor shall be
provided with enclosed, across-the-line type, magnetic controller complete
in a NEMA 250, Type 1 enclosure with "START-STOP" switch in cover. Pump
motors smaller than 746 W Fractional horsepower pump motors shall have
integral thermal overload protection in accordance with Section 16402
INTERIOR DISTRIBUTION SYSTEM. Guards shall shield exposed moving parts.
2.15.3
Booster Pumps
Horizontal split-case centrifugal-type booster pumps shall be furnished.
The capacities shall be as shown, and the speed shall not exceed 1800 rpm.
Pumps shall have a casing of close-grained iron or steel with smooth water
passages. A gasket shall be provided between the upper and lower halves of
the casing. Suction and discharge connections shall be flanged. Impellers
shall be nonoverloading, bronze, balanced to eliminate vibration, and shall
be keyed to corrosion-resisting steel shafts. The casings shall be fitted
with bronze bearing or sealing rings. Bearings shall be cartridge type,
enabling the entire rotating element to be removed without disturbing
alignment or exposing the bearings to dirt, water, and other foreign
matter. Pumps shall be provided with mechanical seals. Seal boxes shall
be machined in the pump casing and at both sides of the pump, and shall be
of sufficient depth to include a conventional bronze seal ring and rows of
shaft packing. Bedplates shall be close-grain cast iron or steel with ribs
and lugs, complete with foundation bolts, and shall have a drip lip with
drain hole. Bedplates shall be close-grain cast iron or steel with ribs
and lugs, complete with foundation bolts, and shall have a drip lip with
drain hole.
SECTION 15405A
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