Specifications - Lord and Son Construction, Inc.

Two-way modulating valves used for liquids shall have an equal-percentage
characteristic. Two-way modulating valves used for steam shall have a
linear characteristic.
2.6.4 Three-Way Valves
Three-way modulating valves shall provide equal percentage flow control with
constant total flow throughout full plug travel.
2.6.5 Valves for Chilled-Water Service
Valve internal trim shall be Type 316 stainless steel. Valves 4 inches and
larger shall be butterfly valves.
2.7 DAMPERS
2.7.1 Damper Assembly
A single damper section shall have blades no longer than 48 inch and shall
be no higher than 72 inch. Maximum damper blade width shall be 8 inch.
Larger sizes shall be made from a combination of sections. Dampers shall be
steel, or other materials where shown. Flat blades shall be made rigid by
folding the edges. Blade-operating linkages shall be within the frame so
that blade-connecting devices within the same damper section shall not be
located directly in the air stream. Damper axles shall be 1/2 inch minimum,
plated steel rods supported in the damper frame by stainless steel or bronze
bearings. Blades mounted vertically shall be supported by thrust bearings.
Pressure drop through dampers shall not exceed 0.04 inches water gauge at
1,000 ft/min in the wide-open position. Frames shall not be less than 2
inch in width. Dampers shall be tested in accordance with AMCA 500-D.
2.7.2 Operating Linkages
Operating links external to dampers, such as crank arms, connecting rods,
and line shafting for transmitting motion from damper actuators to dampers,
shall withstand a load equal to at least 300% of the maximum required
damper-operating force. Rod lengths shall be adjustable. Links shall be
brass, bronze, zinc-coated steel, or stainless steel. Working parts of
joints and clevises shall be brass, bronze, or stainless steel. Adjustments
of crank arms shall control the open and closed positions of dampers.
2.7.3 Damper Types
2.7.3.1 Flow Control Dampers
Outside air, return air, relief air, exhaust, face and bypass dampers shall
be provided where shown and shall be parallel-blade or opposed blade type as
shown on the Damper Schedule. Blades shall have interlocking edges and
shall be provided with compressible seals at points of contact. The channel
frames of the dampers shall be provided with jamb seals to minimize air
leakage. Unless otherwise shown, dampers shall be AMCA 500-D Class 2 and
shall not leak in excess of 20 cfm per square foot at 4 inches water gauge
static pressure when closed. Outside air damper seals shall be suitable for
an operating temperature range of -40 to plus 167 degrees F. Dampers shall
be rated at not less than 2000 ft/min air velocity.
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