The vendor required to provide pivot irrigation system for include:
- Main pipe
• 8 inch – 6-5/8 inch, as required to reach desired flows at desired pressure.
• -0.0115-inch wall thickness.
• Piping will be formed from aisi-sae 1010 coil sheet.
- Pivot assembly
• 8-inch o.d. riser, Poly-seal gasket for high and low pressure.
• 4-inch x 4-inch x 3/8-inch angle iron legs with 4 – 2-inch x 2-inch x 3/16-inch angle braces on all 4 sides.
• Adjustable ring lock elbow.
• Connection between pivot assembly and the first span must be flexible to allow for grade changes on the first tower.
- Truss design
• Truss rods 11/16 inch with manufacturer’s standard heavy duty under truss braces.
- Towers
• Four legs constructed of 3-inch x 3-inch x ¼ inch angle iron bolted to 6-5/8-inch x 11-gauge tubular non-towable mobile base.
• Legs must have a minimum of 5 tie braces.
• Wheelbase minimum 13.0 feet maximum span length 160 feet.
- All towers
• Connections must be of pin and hinge type design with flexible rubber boot with clamps or acceptable approved equivalent.
- Steel structure
• Components shall be hot-dipped galvanized to ASTM 123-73 specifications.
• A minimum coat of 2.00oz/ft² average shall be applied.
- Fasteners
• All fasteners used on the system shall be grade 5 zincs coated or better.
- Hydraulics
• Operating psi 25, maximum 35 psi.
• All systems, will be equipped with 360-degree Senninger spray nozzles, spaced on 120-inch centers, with 30 inch plugged outlets, with plastic plugs.
• Rubber hose drops 3 feet above ground, standard ¾ inch x 12-inch gooseneck use pipe dope on all goosenecks with 1-3/4-pound weights.
• Each drop shall be equipped with a plastic cut-off valve.
• Oversized main line diameters in a combination with the specified minimum diameter shall be provided as necessary for each system to obtain the desired flow volume at the desired operating pressure.
• Minimum flows at 25 psi per system at the pivot point – all calculations shall use a 140-c factor.
- Electric motor on gear drives
• All motors shall be ½ hp, 460-480 vac., 3-phase with 1,725 rpm at 60 HZ, and shall be totally enclosed.
• Full load torque shall be 35oz. ft. (min) and locked rotor torque 220oz. ft. (min) motors shall be rated for continuous duty cycle and have inherent overload protection.
• Motor lead shall be run in ¾ inch conduit along mobile base and extend up tower leg approximately 3 to 4 feet.
- Center drive gearbox
• Spur gear drive gearbox designed specifically for use on center pivot systems.
• Output ratio 40-1.
• The gear drive must be capable of delivering a minimum of 120,000 inch and pounds of instantaneous torques and 36,000 inch and pounds of continuous torque.
- Tire size
• Size 11r238 galvanized, reinforced rims, tubeless.
