Design is where you describe the physical system. The three columns mirror the layout of a real pump station — source vessel and suction pipework on the left, pump and its sketch in the middle, delivery pipework and destination vessel on the right.
New here? Click Load worked example (top right of this tab) to populate a complete 2-duty + 1-standby VSD transfer station you can pull apart and learn from. Clear all returns you to a blank sheet to start your own design.
Every input feeds the same live calculation: static head, friction and fittings losses, total dynamic head, NPSHa, per-pump flow and the pump duty point. The results panels update as you type. The unit selector at the top of this tab controls flow display across every tab in the tool; internal storage stays in m³/h.
Pump & System Curves visualises the hydraulic behaviour of the selected pump set against the system curve you've built on the Design tab.
Chart 1 shows the parallel pump curve(s) at full speed, the parabolic system curve and the design/duty points (same flow, separated vertically by the head safety factor). Chart 2 is the pump efficiency and shaft power vs flow per pump. Chart 3 overlays NPSHa and NPSHr against per-pump flow — where they cross is the practical cavitation limit. Chart 4 appears when VSDs are enabled and plots the full operating envelope with staging triggers.
Charts 1 & 4 share x and y scales (total flow, head). Charts 2 & 3 share their x scale (flow per pump). Tick labels round to clean values.
Power & Cost turns the duty point into operating numbers. Four power tiles step from hydraulic (ρ·g·Q·H per duty pump) → shaft (divided by pump efficiency) → electrical (divided by motor efficiency) → total pumping load across all duty pumps.
The annual operating cost block multiplies total load by your running-hours profile (peak/off-peak split) and electricity tariff to give kWh/year and $/year. Adjust tariffs and hours below to model what-if scenarios; everything recomputes live.
| Period | Hours | Pumps Running | Power Draw (kW) | Energy (kWh) | Cost |
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Surge is a screening-level assessment of pressure transients in your delivery pipeline. It computes worst-case Joukowsky pressure rise on sudden pump trip, estimates the wave celerity from pipe stiffness and fluid bulk modulus, and pre-sizes an air vessel for surge protection if needed.
This is not a substitute for a full transient analysis (Bentley HAMMER, AFT Impulse, KYPipe). It tells you whether surge is likely to be a problem, gives a ballpark vessel size, and flags when you need a transient specialist. Pipe and pump data are inherited from the Design tab.
Surge severity depends on how fast the pressure wave travels along the pipe — the wave celerity, a. That speed is set by the fluid's compressibility and by how much the pipe wall flexes under pressure:
a = √(K/ρ) ÷ √(1 + (K/E)·(D/e)·c)
Allowable surge head rise is the headroom between your normal operating pressure and the pipe's rated maximum — i.e. how much extra pressure (expressed as metres of head) the pipeline can safely absorb. A common basis is the margin to the pipe's pressure class: e.g. a PN16 pipe (≈163 m rating) running at 60 m static has roughly 100 m of margin, but a conservative screening allowance of 20–40 m is typical. Set it to your own (max allowable working pressure − operating pressure), in metres.
A note on thrust blocks. Thrust blocks (and restrained-joint systems) play two distinct roles. In the wave-speed calculation here, by preventing axial movement they put the line in the "fully restrained" case, which slightly lowers the wave speed and surge versus an unrestrained line — a second-order effect. Their primary job, though, is resisting the unbalanced thrust forces at bends, tees and dead-ends that the surge pressure amplifies: a transient can momentarily double the static pressure, so thrust restraint must be designed for the peak surge pressure, not just the steady operating pressure. This tool sizes the surge magnitude; the thrust-block force design itself (bearing area against soil) is a separate calculation.
Process Data Sheet (PDS) is the deliverable an engineer sends to pump suppliers for RFQ. This tab assembles the standard PDS fields from your design state plus the supplier-side parameters in the sidebar, and renders an industry-standard one-page A4 sheet ready to PDF and email.
Most fields auto-populate from the Design tab — you only need to fill in the project metadata, materials selection and any service-specific notes.
Reports & Save produces shareable deliverables and persists your design between sessions.
Export Report generates a PDF (browser print → save as PDF) or CSV of the tabs you select. Save / Load Configuration writes the full state — every input plus every calculated output — to a JSON file in your Downloads folder, and reloads it from any saved JSON. JSON saves are version-controllable and easy to diff between design iterations.
Select which tabs to include in the report. PDF uses your browser's "Save as PDF" — pick that destination when the print dialog opens. CSV exports inputs and calculated values for the selected tabs as comma-separated rows.
Save the complete tool state (all inputs and calculated outputs) as a JSON file to your Downloads folder, or load a previously saved JSON to restore that design. Useful for tracking design revisions or sharing a setup with a colleague.
| Material | k (mm) | Range (mm) |
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| Fitting | K |
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This calculator sizes pumps for water and wastewater treatment applications. It evaluates suction- and delivery-side hydraulics, NPSHa, parallel pump duty, variable-speed drive staging, and power and operating cost based on the design point and the user-defined system curve. It also produces a screening-level surge assessment and a vendor-ready Process Data Sheet (PDS).
H(Q) = Hshutoff − a·(Q/N)² fitted through the design point (with head safety factor applied) and a shutoff-to-design ratio.η(u) = ηmax·(2u − u²) where u = Q / Qdesign.ΔH = a·ΔV/g; wave celerity a = √(K/ρ) / √(1 + (K/E)·(D/e)·c); pipeline period 2L/a; air-vessel pre-size from the Stephenson approximation with a 1.5× margin.PDS values (rated flow/head, NPSHa, absorbed power, suggested motor rating) are drawn directly from the live calculation; supplier-side fields (materials, IP rating, accessories) are user-selected on the PDS tab.
This tool is intended as a design aid for qualified engineers familiar with pumping systems and the limitations listed above. The user is responsible for independent verification of all results against project-specific requirements and vendor data. No warranty is provided as to fitness for purpose; use at your own discretion. Local standards (e.g. Taumata Arowai, DWSNZ for NZ drinking water installations) take precedence over generic engineering practice where applicable.