silencer. Plumbing shall be connected to the vacuum producer through
flexible sleeve connectors. Internal moving parts shall be constructed
with not less than 3.2 mm 0.125 inch clearance throughout to prevent damage
by transient particulates. Impellers shall be constructed of fabricated
sheet metal or high-tensile aluminum alloy, smooth on all surfaces to
prevent imbalance by uneven dust deposits. Impellers shall be of the
backward curved or radial design to provide optimal performance over a wide
range of volume requirements. Impellers shall be securely attached to the
vacuum producer shaft by set screws or clamps of high-tensile material.
Each impeller shall be individually balanced. The complete assembly, with
motor, shall not exceed 0.038 mm 1.5 mils of vibration when given a running
test. Power to operate the vacuum producer shall be in direct proportion
to the volume of air exhausted and shall not exceed the normal motor
rating. The vacuum produced shall be substantially constant throughout the
operating range of the vacuum producer. Each vacuum producer shall have a
minimum capacity, rated in scfm at standard conditions: 101 kPa 14.7 psig
and 21 degrees C 70 degrees F of [_____] standard cu. m per sec scfm
exhaust at [_____] kPa inch Hg vacuum. The vacuum producer shall be sized
to produce the above designated performance standards at the
above-sea-level elevation of the proposed installation site, and shall be
so certified by the manufacturer by equipment tag or plate, or by letter of
certification identifying the vacuum producer by serial number. The motor
for the vacuum producer shall be of a standard NEMA MG 1, 3450 rpm,
T-frame, dripproof design [_____] Vac, 60 Hz, [_____] phase with either
sealed or lubricatable bearings. Operating temperature rise of the motor
shall not exceed 22 degrees C 72 degrees F. Each vacuum producer assembly
shall be mounted on resilient isolator pads as recommended by the
manufacturer. The pads shall not be fastened to the facility floor.
Vibration transmission shall be limited to less than 5 percent of the
lowest frequency of vibration.
2.22.1.2
Pipe Isolators
Flexible, resilient band-sealed (clamped) sleeves shall be furnished to
isolate the vacuum producer from associated piping. Sleeve couplings shall
be sized in accordance with the exhauster intake and output connections.
Pipe isolators shall be provided with steel coupling guards.
2.22.1.3
Valves
a.
Volume Control Valve: The input of each vacuum producer shall
have an adjustable air volume control valve to prevent accidental
vacuum producer overload and to provide a means of adjusting the
upper design capacity limit. The volume control valve shall be
built in or immediately adjacent to the first or input stage of
the vacuum producer and shall be preset by the manufacturer during
certification procedure. The valve shall be a butterfly type with
cast iron body with corrosive resistant internals.
b.
Antisurge Valve: The input of each vacuum producer shall have an
antisurge valve that will operate proportionally and automatically
throughout the vacuum producer's designed range. This valve shall
continually sense the motor current and maintain a predetermined
operational level of volume by proportionally bleeding air into
the system. The valve shall be equipped with a silencer to
attenuate air noise to 85 dB or below. The valve shall be
installed in, on, or near the first stage of the vacuum producer
and can be mounted in conjunction with the directional flow valve.
SECTION 15405A
Page 66
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