A calculation you can defend
Pump power at 250 m³/h and 38 m: hydraulic 25.89 kW, shaft 33.19 kW, suggested motor 37 kW — with the formula printed under the result and the engineering note that matters. Copy the result, or let the Assistant use it inside a report.
Formula printed with every result
Assumptions and defaults visible, editable
Copy as text, or use directly in AI-written documents
The result card: values, formula, engineering note.
Results, not just numbers
Suggested motor ratings, warnings when a value crosses a limit, gauges against thresholds — the calculators answer the next question, not just the arithmetic.
Limit checks colour the verdict
Favourites and recent calculators one click away
Every capability, declared
The complete list.
All thirty-five, by discipline — with their main inputs.
Hydraulics · 8
Pump powerFlow (m³/h), Head (m), Efficiency (0-1), Density (kg/m³)
Pipe head loss (Hazen-Williams)Flow (m³/h), Diameter (mm), Length (m), C factor
Pipe size by velocityFlow (m³/h), Velocity limit (m/s)
Pump affinity lawsFlow at N₁ (m³/h), Head at N₁ (m), Power at N₁ (kW), Speed ratio N₂/N₁
Surge pressure (Joukowsky)ΔV (m/s), Wave speed (m/s), Density (kg/m³)
NPSH marginNPSHa (m), NPSHr (m)
Booster pump headFloors served, Floor height (m), Residual head (m), Friction allowance (%)
Manning open-channel flowManning n, Hydraulic radius (m), Slope (m/m), Flow area (m²) — optional
HVAC · 8
Cooling load (area method)Area (m²), Density (W/m²)
Chilled water flowLoad (kW), ΔT (°C)
Condenser water flowCooling load (kW), Chiller COP, ΔT (°C)
Duct sizeAirflow (L/s), Velocity (m/s)
Supply airflowSensible load (kW), ΔT (°C)
Outdoor air (ASHRAE 62.1)People, Area (m²), Rp (L/s·person), Ra (L/s·m²)…
Fan powerAirflow (L/s), Static pressure (Pa), Efficiency (0-1)
Expansion tank (closed loop)System volume (L), Fill temp (°C), Max temp (°C), Precharge (bar g)…
Electrical · 8
Building electrical loadArea (m²), Density (VA/m²), Diversity (0-1), Power factor
Lighting fixture countArea (m²), Target lux, Lumens per fixture, Utilisation factor…
Motor full-load currentMotor power (kW), Voltage (V), Power factor, Efficiency (0-1)…
Cable voltage dropCurrent (A), Route length (m), mV/A/m (from cable table), Line voltage (V)
Cable size (ampacity + VD)Design current (A), Route length (m), Line voltage (V), Max voltage drop (%)…
Transformer sizingDemand (kVA), Future allowance (%), Max loading (%)
Genset sizingDemand (kVA), Future allowance (%), Step-load margin (%)
UPS battery sizingLoad (kW), Runtime (min), Inverter efficiency, DC bus (V)…
Plumbing · 2
Water demand (Hunter curve)Total fixture units (WSFU), System (flush_tank / flush_valve)
Domestic hot water storageOccupants, Hot water (L/person·day), Peak-period fraction, Recovery time (h)…
Fire · 1
Sprinkler demand & storageDesign area (m²), Density (mm/min), Hose allowance (L/min), Duration (min)
Drainage · 1
Storm drainage (rational method)Runoff coefficient C, Rain intensity (mm/h), Catchment area (m²), Pipe slope (m/m)…
Process · 3
Detention / retention timeVolume (m³), Flow (m³/h)
RO recovery balanceFeed flow (m³/h), Recovery (%)
Storage tank sizeDaily demand (m³), Storage (days)
Structural · 1
Tank flotation checkBase area (m²), Submerged height (m), Structure weight (kN), Anchorage (kN)
Vertical transport · 1
Lift traffic checkBuilding population, Car capacity (persons), Round-trip time (s), Number of cars…
Project controls · 1
Earned value (EVM)Planned value (PV), Earned value (EV), Actual cost (AC), Budget at completion (BAC)
Utilities · 1
Unit converterValue, Conversion (e.g. psi_to_bar)
Against the field — calculations
35 verified calculators inside the project workspace
A folder of personal spreadsheets nobody dares audit
Formula and assumptions printed with the result
A cell with =0.746*B4/0.7 and a prayer
The Assistant uses the same calculators in written deliverables
Numbers retyped from Excel into Word, drifting
"The markup suite" is the well-known per-seat PDF application; "the construction cloud" is the big per-user-per-month platform. Both excellent at what they chose — the difference here is one integrated record, on your own server.
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