Pipe, Hydraulic & Chilled Water Calculators
Practical HVAC and piping calculators for chilled-water flow, pipe sizing, water volume, operating weight, velocity, pressure drop, pump head, flushing and hydrotest quantities.
1. Pipe Water Volume, Empty Weight & Operating Weight
Calculate internal volume and approximate pipe/water mass using actual outside diameter, wall thickness, length and material.
2. Chilled Water Flow Calculator — kW / TR to m³/h, L/s & GPM
Calculate required chilled-water flow from cooling duty and water temperature difference.
3. “What Pipe Size Do I Need?” — CHW Pipe Sizing
Enter cooling load and target velocity to calculate minimum hydraulic inside diameter. The result is a preliminary sizing aid; final pipe selection should also check pressure loss, available pipe schedules and material grades, fittings and project criteria.
4. Pipe Velocity Calculator
5. Pipe Pressure Drop & Friction Loss — Darcy-Weisbach
Calculate straight-pipe friction using Reynolds number and a Darcy friction-factor approximation. Optional ΣK adds minor losses from fittings and valves.
6. Pump Head / Total Dynamic Head Calculator
Add the required system components to estimate total pump differential head.
7. Filling & Flushing Water Quantity
8. Hydrotest Fill Water Quantity
9. Water Thermal Expansion — Preliminary Volume Change
Estimate the change in contained water volume between two temperatures. This is not a final expansion-vessel sizing calculation.
10. Engineering Unit Converters
Cooling Capacity
Water Flow
Pressure
Temperature
Engineering Formula Reference
| Calculation | Formula / Basis | Practical Use |
|---|---|---|
| Water heat transfer | Q = ṁ Cp ΔT | CHW flow from cooling duty |
| Pipe velocity | v = Q / A | Hydraulic pipe sizing |
| Reynolds number | Re = vD / ν | Flow regime / friction factor |
| Darcy-Weisbach | ΔP = f(L/D)(ρv²/2) | Straight-pipe friction loss |
| Minor losses | ΔP = ΣK(ρv²/2) | Elbows, valves, fittings |
| Water volume | V = πD²L/4 | Filling, flushing, hydrotest |
Common Questions
How much chilled-water flow is required per TR?
It depends on the selected chilled-water ΔT. The calculator uses heat balance rather than one fixed GPM/TR rule.
Can I size a CHW pipe from cooling load alone?
Cooling load and ΔT determine flow. A preliminary diameter can then be calculated from target velocity, but final sizing should also consider pressure loss, fittings, control authority, noise, available pipe schedules and project criteria.
Does a closed chilled-water pump overcome building height?
In a completely filled closed loop, elevation on the supply side is balanced by the returning water column. Pump differential head is primarily required to overcome system resistance; system pressurization is a separate design consideration.
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