Description
The primary purpose of this valve station is to provide pressure
control over a large range of flow rates at a fixed point in the irrigation system. The station shall be designed such that -
A. System pipe breaks and leakage are minimized, based on
best practice design principles.
B. Ease of System Maintenance is of primary importance.
C. System Performance is reliable and consistent and matches
certified design criteria.
A secondary purpose of this valve station may be to provide onoff flow control to the system.
Features
A. System pipe breaks and leakage are minimized based on
best practice design principles
The valve station shall be designed such that the following
capabilities may be achieved -
1. Maintain system pressure at a constant pressure that will
provide adequate discharge from the worst case Station or
Head from 20% to 100% of design flow.
• No more than 10psi variation at steady state flow over
entire operating range from 20% to 100% of continuous
flow range.
2. Reduce or eliminate pressure spike or "Water Hammer"
events by minimizing operating pressure during operation.
• Field adjustable closing speed on pressure or flow control
valves.
• Field adjustable set point with minimal "drop off" as flow
rate increases.
• Ability to set the stable pressure as low as possible while
maintaining "A1" (see above). Range: 40 – 120psi set
point.
3. Provide a means to drastically reduce system pressure when
the system is idle.
• Provides a small pre-load valve to maintain a constant low
pressure to the system during idle times.
• A low flow rate valve is ideal in order to conserve water
should pipe leaks be prevalent.
4. Minimize the amount of piping that is subjected to high
purveyor supply pressure.
• Provide a valve station as near to the purveyor connection
as possible.
B. Ease of System Maintenance is of primary importance.
1. Provide for ease of access.
• Valve Station shall be designed to be installed so that all
equipment that may require scheduled maintenance or
repair is above ground.
2. Provide for means to determine functionality.
• All equipment subject to inspection for maintenance /
repair / or performance evaluations shall be designed such
that proper operation can be determined through external
test methods rather than solely by disassembly and
inspection.
3. Provide for means of in-line repair or ease of replacement.
• All equipment shall be flanged, or installed with unions or
grooved couplers.
• Adequate Spacer Flanges shall be used to ensure that
compensation for manufacturing variations in equipment
lay length may be made.
C. System Performance is reliable and consistent and matches
certified design criteria.
1. Provide fully matched and certified components in a preassembled and certified valve station.
• Wherever possible, a single manufacturer's components
shall be used in the Valve Station Assembly.
• Valve Station vendor shall provide a certified submittal with
bill of materials which will detail the primary customer connection dimensions, the installed equipment, and the
materials of construction for approval prior to fabrication.
• Vendor shall provide a pre-assembled Valve Station that
has received at a minimum full hydro-test to 1.5 times the
design supply pressure for 5 minutes.
• Vendor shall provide performance data submittals for comparison of proposed Valve Station performance to system
design criteria.
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