panel door shall be provided. A ground fault protected convenience outlet
shall be provided. The enclosure shall be of NEMA [3R] [4X] [_____],
[painted steel] [Type 300 series stainless steel] construction, factory
wired and tested. The pump and carriage motor controls shall be magnetic
contactors with thermal overcurrent protective devices.
2.5.9.3
Motors
Controls, a timing device, relays and magnetic motor starters for each pump
motor and carriage motor shall be included in the panel. These motors may
be actuated automatically by a predetermined increase in hydraulic head, or
by the timing device to control the interval between each cleaning cycle.
[The cleaning cycle shall be terminated by a signal from the low water
sensing electrode. The "off time" of the cleaning cycle shall be
controlled by a reset timer with a range of 1 minute to 60 hours. When the
timer times out, the motors shall be actuated. During the "on time", the
timer shall be de-energized and reset for starting "off time" at the end of
the cycle. Should high water occur "off time", the motors shall be started
by a relay actuated from the high water electrode signal, with a
corresponding resetting of the timer.] [The washing cycle, when activated,
shall continue for one complete pass of the filter bed. Under normal
operation, the carriage shall not come to rest other than at either end of
the filter.]
2.5.9.4
Backwash Mechanism
The control sequence for the backwash mechanism shall be wired so the
backwash mechanism stops at either end of the filter upon termination of
the backwash cycle, which will be at the low operating probe signal. A low
water shutoff probe shall prevent pumping the filter tank below the minimum
water level point. Additional electrodes shall be furnished to protect the
submersible pumps by giving a signal prior to reaching the overflow point.
2.5.9.5
Electrification System
A stretch cable electrification system shall be provided. The cable shall
be [_____] diameter stainless steel. A stainless steel turnbuckle shall be
provided at one end for cable tension adjustment. The electrification
system shall be equipped with a number of non-friction nylon trolley
carriers which shall support the electrical flat cable used to power the
carriage. The electrification system shall connect to a NEMA [4X] [3R]
[_____] [Type 300 series stainless steel] [fiberglass reinforced plastic]
equivalent junction box.
2.5.9.6
The Contractor shall submit test reports of all factory tests specified in
the above paragraphs and throughout this specification.
2.5.10
2.5.10.1
Pumps
The backwash and washwater systems shall each be powered by a submersible
pump suspended from the filter carriage. Only dual submersible pumps will
be acceptable. Each pump shall provide a minimum pumping rate of [_____]
at a head of [_____]. The pumps shall be equipped with stainless steel
shafts, and abrasive-resistant impellers. Pumps shall be supplied in
accordance with the requirements of Section 11211 PUMPS: WATER, CENTRIFUGAL.
SECTION 11393
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