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Centre Pivot Design · IRR-006

From advanced drip design to centre pivots.

The heavy end of irrigation design — centre pivot and lateral-move machines, advanced dripline and vineyard/orchard design, hydraulic zoning, branching mainlines and submains, air-valve placement and dam yield. Tenselo sizes the whole machine: span and tower schedule, pipe package, sprinkler pack, end gun, pivot duty and the pump behind it — then checks application rate against soil intake before you quote it.

A worked example

Valley (Valmont) — 6-span centre pivot, 400 m radius

50 ha full circle · Mildura VIC · sandy loam · bore 400 m away

These figures come from the Tenselo engine. Every result Tenselo produces shows the inputs it used and the method behind it, so the work can be checked rather than taken on trust.

Inputs
Field area 50 ha
Wetted arc 360 deg
Peak ETo region Mildura, VIC
Application efficiency 85 %
Operating hours 22 h/day
Target depth per pass 25 mm
Soil / slope Sandy loam, 3%
Delivery main 400 m, 12 m lift
Results
6 towers
Spans / drive towers
66.4 L/s
Pivot flow (239 m³/h)
293 kPa
Duty at the pivot inlet
50.0 m
Full pump TDH
50.5 kW
Pump power at duty
280 mm
Delivery main, PN6.3 HDPE
16.0 h
Rotation at 100% timer
5.3 ML/day
Daily capacity (10.5 mm)
2.6
Application vs soil intake

Why it matters on the job

The machine, not just the duty point

Span and tower schedule, pipe package stepped by velocity, sprinkler pack, drive gearboxes and end gun — the parts list for an actual machine, on your field area and your peak ETo.

The pump behind the pivot, sized properly

The pivot inlet duty is only half the job. Tenselo carries it back through the delivery main and the source lift to a full pump duty — 66.4 L/s at 50.0 m TDH here — and names a candidate pump and motor to price.

Runoff caught before the quote, not after

Outer-span application rate is checked against the soil's intake at your slope. A ratio over about four turns the report amber, because that is water running off the outside of the circle instead of into the crop.

Advanced dripline and vineyard design too

Emitter uniformity end-to-end, lateral and submain sizing, bicarbonate and acid injection to stop drip scaling, and filtration sized to the emitter — the drip side of advanced design, not only the machines.

Hydraulic zoning and branching mainlines

Flows, velocities and node pressures through a non-looped branching network, so shifts and zones balance and the pump sees a steady duty rather than a swinging load.

Air valves, dams and the rest of the scheme

Air-valve locations and types read off a pipeline elevation profile, and monthly dam yield against demand with spills, deficits and reliability.

What is in this category

20 Irrigation Advanced Design calculators

Every calculator in this category, by its reference code. Running them needs a Tenselo subscription — subscriptions open soon.

  • ISD-001 Air-Valve Placement from Profile

    Recommends air-valve locations and types from a pipeline elevation profile

  • ISD-002 Bicarbonate Neutralisation / Acid Injection

    Acid dose and injection rate to cut alkalinity/bicarbonate and reduce drip scaling

  • ISD-003 Branching Mainline / Submain Tree

    Flows, velocities and node pressures through a non-looped branching network

  • ISD-004 Dam Yield / Monthly Storage Reliability

    Monthly dam water balance vs demand - spills, deficits and reliability

  • ISD-005 Drip Flush Manifold / Flush Velocity

    Flush flow, time and manifold/valve size to flush a drip block at the target velocity

  • ISD-006 Fertiliser Stock Solubility / Tank Size

    Checks whether a fertiliser mass dissolves in the batch tank at temperature

  • ISD-007 Field Fertigation Nutrient Injection

    Product mass, injection rate and tank from a nutrient target (kg/ha or ppm)

  • ISD-008 Filter Station Backwash Sequencing

    Can the station backwash while still supplying the field? Flow, vessels online and wash water

  • ISD-009 Intake Screen / Trash-Rack Sizing

    Screen face area from flow, approach velocity, open area and fouling allowance

  • ISD-010 Media Filter Bed Expansion

    Backwash flow, indicative bed expansion and freeboard/washout check

  • ISD-011 Network Pressure Balance / HGL

    Hydraulic grade line along a mainline to each outlet/valve block (Hazen-Williams)

  • ISD-012 PC Emitter Range Check

    Checks emitters stay inside the pressure-compensating band (or estimates non-PC flow variation)

  • ISD-013 Pipe Buoyancy / Flotation Check

    Will a buried/submerged pipe float when empty? Uplift vs weight + soil cover, with FoS

  • ISD-014 Pipeline Fill, Drain & Air-Release Time

    Fill/drain time, fill velocity and the air an air-valve must pass on a pipeline

  • ISD-015 Pump Intake Submergence / Vortex Check

    Minimum submergence to stop a vortex, plus floor/wall clearance and screen approach velocity (ANSI/HI 9.8)

  • ISD-016 Pump Station Staging & VSD Setpoint

    Pump count, VSD speed and pressure setpoint for a station feeding several demand groups

  • ISD-017 Restrained Length / Anchor Length

    Thrust at a fitting and the restrained-joint length to resist it by soil friction (DIPRA/AWWA design aid)

  • ISD-018 Settling Basin / Silt Trap Sizing

    Surface area and volume to settle sand/silt ahead of filtration (overflow-rate basis)

  • ISD-019 Sprinkler Application Rate vs Soil Intake

    Checks sprinkler precipitation rate against soil infiltration for runoff and cycle-soak

  • ISD-020 Whole-Farm Water Budget

    Seasonal crop water demand vs allocation, storage and peak-day supply

The centre pivot machine design and pivot pumping-cost calculators are filed under Irrigation — Field & Crop, alongside the scheduling, uniformity and sprinkler-pack tools they work with.

IRR-006, IRR-021 See Irrigation — Field & Crop →

Subscriptions open soon

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