minimum design & construction standards - Martin County, Florida

4. Automatic Control Valve
The Automatic Control Valve shall maintain a maximum (adjustable) flow rate regardless of
changes in demand or inlet pressure variations. The valve will also modulate to maintain a
constant (adjustable) downstream pressure. The valve shall be equipped with a solenoid
intercept that will close the valve drip-tight upon actuation. Valve manufacturer for pilot set
points and individual orifice bore sizes shall determine control ranges. The valve shall be
equipped with an orifice bore assembly that will fit between two standard pipeline flanges;
no pilot tubes shall be allowed.
The valve shall be hydraulically operated, diaphragm actuated, and angle pattern. The
valve shall be single chamber with a single diaphragm. The diaphragm assembly shall be
the only moving part and shall form a sealed chamber between the valve body and cover,
allowing for a separation of operating pressure and pipeline pressures. Internal packing
glands are not permitted within the main valve. The valve body shall be stainless steel*
construction with stainless steel trim. The valve shall have 125/150 lb. flanged ends
(stainless valves shall have steel flanges). The valve must be fully serviceable in the
pipeline, and the diaphragm may not be used as a seating surface. The main valve and
controls shall be manufactured in the United States of America.
* Valves 4” and larger to have stainless steel body. Valves 3” and smaller to be cast
iron epoxy coated on the inside and outside with stainless steel trim.
The main valve shall have a single removable stainless steel seat that seals against a
resilient, synthetic rubber disc. This disc shall have a rectangular cross section and be
surrounded on three and one-half sides of the cross section by the module formed by the
disc retainer and the stainless steel contoured disc guide. No O-ring type discs shall be
permitted as the seating surface interface. The main valve stem shall be fully guided at
both ends by a bearing in the valve cover and an integral bearing in the stainless steel seat.
The seat shall have a five-degree higher taper on the seat diameter, so as to insure drip
tight shut off. The cover bearing shall be aligned so as to permit freedom of movement of
the diaphragm assembly; center guides in a single chamber valve are not permitted.
Machined surfaces in the body and cover shall fully support the diaphragm throughout the
valve stroke and over the entire 360 degrees of the diaphragm radius. The flexible, nonwicking
diaphragm shall be FDA approved and consist of nylon fabric bonded with synthetic
rubber compatible with chlorinated reuse water. The center hole accommodating the main
valve stem must be sealed by vulcanized rubber grommet. The diaphragm must withstand
a Mullins Burst Test of a minimum of 600 psi per layer of nylon fabric and shall be cycle
tested 100,000 cycles to insure material longevity.
The control valve shall utilize a solenoid valve operating at 120 VAC for opening and
closing of the control valve. Additional manually operated ball valve(s) shall be plumbed in
parallel with the solenoid valve to allow manual means to open and close the control valve
in case of failure of the electrical devices.
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