cannot be tolerated and there is a need for
automatic control ensuring constant hydronic flow,
the design will incorporate automatic flow-control
valves indicating their location and capacity on the
drawings. The required pump head will be shown on
the drawings.
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In lieu of the specified balancing valves, automatic flow control valves
may be provided to maintain constant flow and shall be designed to be
sensitive to pressure differential across the valve to provide the required
opening. Valves shall be selected for the flow required and provided with
a permanent nameplate or tag carrying a permanent record of the
factory-determined flow rate and flow control pressure levels. Valves
shall control the flow within 5 percent of the tag rating. Valves shall be
suitable for the maximum operating pressure of 850 kPa 125 psi or 150
percent of the system operating pressure, whichever is greater. Where the
available system pressure is not adequate to provide the minimum pressure
differential that still allows flow control, the system pump head
capability shall be increased. Valves shall be suitable for 120 degrees C
250 degrees F temperature service. Valve materials shall be same as
specified for the heating system check, globe, angle, and gate valves.
Valve operator shall be the electric motor type or pneumatic type as
applicable. Valve operator shall be capable of positive shutoff against
the system pump head. Valve bodies shall be provided with tapped openings
and pipe extensions with shutoff valves outside of pipe insulation. The
pipe extensions shall be provided with quick connecting hose fittings for a
portable meter to measure the pressure differential across the automatic
flow control valve. A portable meter shall be provided with accessory kit
as recommended for the project by the automatic valve manufacturer.
2.11.18.10
Butterfly valves shall be 2-flange type or lug wafer type, and shall be
bubbletight at 1135 kPa 150 psig. Valve bodies shall be cast iron,
malleable iron, or steel. ASTM A 167, Type 404 or Type 316, corrosion
resisting steel stems, bronze, or corrosion resisting steel discs, and
synthetic rubber seats shall be provided. Valves smaller than 200 mm 8
inches shall have throttling handles with a minimum of seven locking
positions. Valves 200 mm 8 inches and larger shall have totally enclosed
manual gear operators with adjustable balance return stops and position
indicators. Valves in insulated lines shall have extended neck to
accommodate insulation thickness.
2.11.18.11
Drain valves shall be provided at each drain point of blowdown as
recommended by the boiler manufacturer. Piping shall conform to ASME BPVC
SEC IVand ASTM A 53/A 53M.
2.11.18.12
Safety Valves
Safety valves shall have steel bodies and shall be equipped with
corrosion-resistant trim and valve seats. The valves shall be properly
guided and shall be positive closing so that no leakage can occur.
Adjustment of the desired back-pressure shall cover the range between 15
and 70 kPa 2 and 10 psig. The adjustment shall be made externally, and any
shafts extending through the valve body shall be provided with adjustable
stuffing boxes having renewable packing. Boiler safety valves of proper
SECTION 15569A
Page 51
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