Calculation and sizing

Design parameters (Design → Design parameters)

New projects, the last section of the dialog, says what the next new projects start with and where each value comes from (the region of the machine, your choice or the program's default): the mains frequency (60 Hz in North and Central America, the Caribbean, Brazil, Colombia, Venezuela, Ecuador, Peru, Guyana, Suriname, Saudi Arabia, Korea, Taiwan, the Philippines, Japan, several Pacific islands and Liberia, 50 Hz elsewhere) and the currency of the region unless you chose them, and the units you chose (US units never come from the region alone). Use these parameters for new projects keeps every parameter of the open project (velocities, losses, economics…) as the template of the next ones, which keep the currency of their catalogue (an energy price kept in another currency is converted); Back to the region's defaults forgets the choices.

Calculation steps

1. Graph construction: entities → nodes and links; coincident vertices merged; point items inserted into pipes; laterals lumped; terrain elevation at every node; zones identified from every valve; fittings (bends and tees) found when the local losses come from them.
2. Zones, one by one:
   • initial sizing by maximum velocity, which also provides the nominal flows;
   • LP: every sizable unit may be built from fractions of the candidate diameters; the linear programme minimises the annualised pipe cost plus the energy cost of the inlet pressure, subject to the pressure window of the critical emitters (the end, the highest and the lowest point of every lateral, every single emitter). If the analysis does not confirm the window, the emitters at minimum and maximum pressure become constraints and the LP runs again (up to four rounds);
   • pressure class: the LP and the greedy steps offer each unit only the pipes whose class, at the water temperature, withstands the pressure the analysis found there plus the water hammer of the screening of step 6 (PVC loses part of its class above 25 °C and PE above 20 °C); when a pass ends with a pipe below its pressure, the unit's requirement rises and the zone is sized again (up to three passes). With nothing in the catalogue strong enough the unit is sized as before and the class is reported exceeded;
   • repair: greedy diameter increase along the critical path until the window is met (when the elevation range of the emitters alone exceeds the window, no pipe is bought for it and the zone says so: zone_slope_exceeds_window);
   • rationalisation: non-increasing diameters from upstream to downstream and telescoping within the limit of diameters per unit;
   • detailed analysis: non-linear network with pressure-dependent emitters; the pressure downstream of the valve is chosen by bisection so that the mean emitter pressure equals the nominal one (or, for regulated tapes, to guarantee the minimum submain pressure);
   • results: zone flow, minimum and maximum pressures and the allowable ones, allowable and actual variation, required valve pressure, valve loss, uniformity (Christiansen CU, low-quarter DU, Keller-Karmeli EU with the manufacturer CV and emitters per plant, statistical uniformity, flow variation), overlap CU for sprinklers with a wetted radius, pipe table with pressures, elevations and velocities, emitter table.
3. Mainline, per system flow: demand and required pressure of every valve, pivot (what its sprinkler package needs) and scheduled valve-in-head station, LP over all flows with the energy cost weighted by the hours of each and the same pressure-class passes; in a looped mainline the LP holds the energy balance of every loop for the flows it sizes for, and since the sizes decide how the flow splits it is solved again with the flows of the new sizes until the choice settles (up to four more times; a note of approximation is left only when the flows do not settle). With a calculated supply, the grade line is kept above the pipe at the high points of the profile (in the LP and in the analysis), and a high point without an air valve is pointed out (air_valve_missing, information). Then the analysis of every flow with pumps (operating point; a variable-speed drive finds the speed that holds its target outlet pressure; the NPSH available is compared with the pump's curve; a pump station runs the duty pumps the flow needs, staged by flow, on the joint curve of those running, with the duty of each), valves with reducing or sustaining pilots, pressure-reducing, pressure-sustaining and flow-control valves, check valves and fixed- or calculated-pressure supplies; duty of every supply (flow, available pressure, required pressure, deficit) and annual energy. With the real operation of the zones on, every zone and pivot then runs at the pressure the mainline delivers to it, as an equivalent emitter behind its valve (a regulating valve holds its setting, a sustaining pilot its upstream pressure), adjusted until the zone and the line agree.
4. Telescoping: pipes with more than one diameter are split into entities, largest diameter upstream, and the affected zones are re-analysed.
5. Flushing: every zone with tapes is analysed with the ends open at the flushing velocity; reports the flushing flow, the required valve and upstream pressure, number of tapes, minimum end pressure and maximum velocity.
6. Water hammer: along the path of the water from the supply (from the valve, in a zone), every point of a pipe gets Michaud's envelope at its distance x, min(a·ΔV/g, 2·x·ΔV/(g·T)), with the wave celerity a from the material and wall and the closure time T, over the static pressure there; the worst point of each entity is compared with the pipe rating and the report shows the path used (the full transient analysis is Mainline → Hydraulic transients…, below).
7. Mechanised machines: the sprinkler package and timer chart of every centre pivot and linear move and, when their data are given, the corner arm, the variable-rate prescription and the electrical design (see Mechanised machines and field calculators).
8. Valve wiring (when the drawing has a controller or a wire route): shortest route from each controller to every valve, stations in order of distance, and, for every controller, the common wire and the station wire of every valve with the lowest cost such that each solenoid, while opening (inrush current) with the other valves of its system flow already on (holding current), gets at least the minimum voltage. The drop is I·R·L on the station conductor plus, on every stretch of the common, the current of the valves beyond it; lengths include the slack. Without system flows every valve is on at once, as in the hydraulic design. A master valve is on with every zone (output 0, its own wire, its current on the common), and every valve-in-head station takes a station with its heads in parallel. Reports stations, route and wire lengths, wire sizes, solenoid voltages and the peak current of every controller; warns about valves without wire, routes reaching no controller, controllers with too few stations or opening more valves than they drive at once, and voltages below the minimum.
9. Materials: pipes by diameter and rating, emitters, tapes, valves, devices, pumps (with automatic selection from the catalogue and a standard IEC motor; pump hour meters), pivots with towers, sprinklers and regulators, fittings selected automatically from the geometry (couplers per stick, elbows, tees, crosses, reducers, end caps, lateral take-offs, tape ends, risers) and the electrical items (wires by size, controllers and their accessories, two waterproof connectors per valve), with costs, FINAME codes where the catalogue has them, annualised cost (capital recovery factor) and energy; also split by sector (Materials by sector) and for the current selection (Edit → Materials of the selection…). The standby pumps of pump stations, the air vessels, the block references marked to count, the traveller lanes and furrows and, when they are switched on, the parts of the pump house electrics, the solar array and the two-wire system (Power, water and machines) are listed too. Pipe lengths run along the ground (√(L² + Δz²) with the terrain at both ends), in the losses as in the bill of materials.

The calculation runs in a Web Worker in the browser (or in an isolate on desktop) and returns the resized entities and the results to the interface; while it runs, editing is blocked so that no change is lost (unless Edit while the design runs is on in View → Snaps and drawing…: the design then works on a copy and its results, out of date, are discarded), but navigation, reports and other tabs stay free; the progress card has a Cancel. With Design → Analyse automatically while editing, a moment after every edit the design is analysed again without sizing, so pressures, flows and messages follow the drawing (a chip in the status bar shows it).

Design check

Calculation messages

Every zone, system flow and step may emit warnings, shown in the Messages tab and next to the item: pressure outside the window, velocity exceeded, pressure rating exceeded (in operation or by water hammer), valve outside its flow range, pump off its curve, NPSH available below what the pump requires, a variable-speed drive that cannot reach its target pressure or would need less than its minimum speed, supply flow or pressure exceeded, pressure deficit at a valve, pivot or valve-in-head station (or a station above its window, or in no flow), infeasible LP (with the greedy method taking over), looped mainline (the LP holds the energy balance of every loop and repeats with the new flows; the final analysis checks), missing catalogue components, pivot application rate above the soil limit, a pump below the minimum flow of its curve or above its motor power, the LP stopped at its iteration limit (the greedy method then sizes), the elevation range of a zone beyond the emitter window, a zone that a regulating device keeps below its nominal pressure, pressure below the atmosphere in a pipe (the grade line under it), surplus pressure at a zone valve that does not regulate, a station or a system flow drawing more current than the controller gives, the flows of a day that do not fit the irrigation window, among others.

Design assistant: explanations and one-click corrections

The Messages tab and the design check show every problem as a card: what happened, why it matters and how to fix it, a button to show the item on the drawing, Ask the AI (which opens the AI assistant with a question about that message; nothing is sent until you press Send) and, when there is one, a button that fixes it (each correction is one undo step). Besides the drawing and the results, the assistant checks impossible settings: velocity, hours, economic parameters, tolerance, zone variation or water temperature out of physical ranges, no enabled catalogue pipe for a use, supply maxima below the design values, zones in no system flow, empty flows, emitter pressures outside the nozzle range, pump speeds out of range.

• Corrections: join an item dropped next to the pipe, remove zero-length pipes, repeated vertices and duplicates, rename repeated zones, choose (or insert) the pump with the lowest life-cycle cost, replace a surface pump that cannot lift the water with a submersible one, a pipe of a higher pressure class, a valve of the right size, split the zones into more system flows, restore default parameters, add the zones left out to a flow, the nominal emitter pressure, a controller with enough stations (the next standard size), enable the catalogue wires, split an area that crosses itself into simple areas, keep one of two pipes drawn over each other, join a loose sprinkler to the nearest pipe by a short pipe, design with the supply maximums, and more.
• Fix automatically (Design menu, FIX): safe corrections and designs in rounds until nothing more can be fixed, all in one undo step, with a summary of what changed and what needs a decision (a pump on public mains, new system flows: never applied on their own).
• Optimise design (Design menu, OPT): lowest annual cost (annualised investment + energy) that meets every requirement — LP sizing, the smallest suitable valves and the pump with the lowest life-cycle cost — in steps, each kept only when it improves and brings no new warning, with a before / after comparison.
• Both list every correction or change with a tick box and a button that shows it on the drawing: Keep only the ticked ones takes the project back and makes only those again, in one undo step.
• After a design with errors the Messages tab opens by itself and shows how many problems there are.

Analyses of the mainline and of the operation

These run on the designed project (each says what is missing when there is no design or no water supply); what they propose (inserted air valves, start hours, system flows, wire routes, a C factor) is applied as one undo step. The long ones (on-demand operation, criticality, calibration, the tariff schedule, the energy grouping, the design over its life) show their progress and stop with Cancel.

Agronomy, mechanised machines and field calculators

• Site climate (Design → Site climate…): monthly normals of ETo (FAO Penman-Monteith), rain (mean and dependable), solar radiation, minimum humidity and wind at 2 m, downloaded for the site from NASA POWER (the default, free for any use) or Open-Meteo (historical weather, ERA5; for non-commercial use), read from an INMET station file, worked out from the normals of a station, or typed in, kept in the project with their source. The daily soil water balance, the irrigation programme, fertigation by stage, field uniformity and user crops are in Agronomy and irrigation scheduling; the pump house electrics, solar pumping in the design, water quality, two-wire wiring, several pivots, traveller lanes and furrows in Power, water and machines.
• Crop requirement (report tab): every irrigated area with a crop of the FAO-56 table gets its table by month and growth stage from the site climate, its soil (12 USDA texture classes), the effective rain method (USDA-SCS, FAO/AGLW, FAO empirical, a share of the rain), the leaching requirement for the water salinity (FAO-29) and, for drip, the ground-cover reduction of Kc; totals per area and the CONAMA 284/2001 licensing category by method and area (informative).
• Mechanised machines: the Properties of a pivot or linear move open Package, timer, arm, VRI and electrical…: the sprinkler package (flow per outlet for a uniform depth, regulators, drops, numbered nozzles or catalogue nozzles, end gun and booster), the timer chart from the drive train, a corner arm following a guide path (with its jump warning), a variable-rate prescription by zones or sectors (CSV) and the electrical design (cable drop span by span, motor starting, generator size). The Pivot package and Arm, VRI and electrical tabs list them.
• Calculators (Tools menu): lateral (maximum length, losses and uniformity of a lateral or tape on a slope); pump and system curve (operating point, power and annual energy); water hammer (Joukowsky surge against the pipe rating); solar pumping (PV array for the daily volume of every month, with the grid comparison); wetted bulb of a drip emitter and the wetted share of the area; landscape water budget (MAWA and ETWU, with cycle-and-soak run times); hose-reel traveller (lane spacing, speed, depth, hose friction, inlet pressure); surface irrigation (furrows, borders and basins by volume balance: advance, cutoff, efficiencies); gated pipe (gate openings or hole sizes for a flow per furrow).