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Pipe Diameter, Flow Rate & Velocity
Calculate pipe internal diameter, flow rate, or flow velocity. Enter any two of the three values to calculate the third using the continuity equation.
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Flow Coefficient (Cv / Kv)
Calculate a valve's flow coefficient (Kv / Cv) from flow rate and pressure drop, or determine flow rate or pressure drop from a known coefficient, for water and other liquids.
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Thermal Expansion & Contraction
Calculate thermal expansion in pipework — including change in length, expansion loop leg sizing using the guided cantilever method, and the axial restraint force in a fully fixed pipe.
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Heat Load & Flow Rate
Calculate the thermal power transferred in a heating or chilled water system using Q = ṁ × Cp × ΔT, for water or glycol mixtures. Solve for heat load, flow rate, or temperature differential.
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Ductwork Pressure Drop
Calculate air velocity, friction factor and pressure drop in circular or rectangular ductwork using the Darcy-Weisbach equation, with the friction factor from the Swamee-Jain approximation to Colebrook-White.
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Gravity Drainage
Calculate full-bore flow capacity, required internal diameter, or required gradient for gravity drainage pipes using the Colebrook-White equation (BS EN 12056-2) or Manning's equation, with Approved Document H Table 6 minimum gradient checks for foul drains.
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Time to Empty Tank
Calculate the time to drain a tank under gravity using Torricelli's theorem. Supports vertical cylindrical, rectangular, and horizontal cylindrical tanks.
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Volumetric Flow Rate
Convert volumetric flow rates between litres per second, litres per minute, litres per hour, cubic metres per hour, and UK/US gallons. Optionally calculate volume discharged over a given time period.
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Control Valve Sizing
Size a two-port control valve by calculating the required Kv and comparing the nearest standard sizes, check design and minimum valve authority against CIBSE Guide H, and evaluate rangeability for equal-percentage or linear characteristics.
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Pipe Support Spacing
Calculate the maximum support spacing for pipework from pipe material, size, fluid content, insulation and the governing limit (deflection or bending stress). Includes reference tables for copper and steel pipe size series, with BS EN 806-4 recommended spacings for copper.
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LMTD & Heat Exchanger Area
Calculate the Log Mean Temperature Difference for counter-flow or parallel-flow heat exchangers, and determine the required heat transfer area from duty, LMTD, and overall heat transfer coefficient.
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Fan Power
Calculate the shaft power drawn by a fan from volume flow rate and total fan pressure, or back-calculate flow rate or total pressure from a known shaft power input and efficiency.
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Differential Pressure & Head
Convert between differential pressure and equivalent fluid head, and convert pressure values between bar, kPa, mbar, psi, and other common units used in building services.
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Nominal Pressure vs Temperature
Look up the maximum allowable working pressure at temperature for flanges (BS EN 1092-1/-2), copper fittings (BS EN 1254) and plastic pipes (PE100, PVC-U, PE-X, PP-R, PVC-C), using published pressure–temperature data.
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Pipe Insulation Heat Loss
Calculate the heat loss (or heat gain for chilled pipework) per metre from an insulated pipe, or the insulation thickness needed to meet a target heat loss, using the radial heat conduction equation for a cylindrical shell.
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Commissioning Valve Flow Rate
Calculate the flow rate through a commissioning valve from its Kv and a measured differential pressure, the Kv needed for a target flow, or the expected differential pressure at design flow — with a specific gravity correction for glycol mixtures.
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Distributed & Localised Pressure Drops
Calculate distributed pressure losses in pipe sections using the Darcy-Weisbach equation (with Colebrook-White friction factor), and localised losses in fittings using Kv or zeta (ζ) coefficients.
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Flange Connector Installation
Calculate bolt tightening torque and the star-pattern tightening sequence, look up BS EN 1092-1 flange and bolt dimensions, and check gasket bolt loads to ASME VIII Appendix 2 using standard BS EN 1514-1 gaskets or your own gasket dimensions.
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Glycol Freeze Protection
Determine the glycol concentration required for a target freeze protection temperature, or calculate fluid properties — density, specific heat, and viscosity — for a given glycol type and concentration.
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Relief Valve Sizing
Calculate the minimum orifice area for a pressure relief valve in liquid service, or the capacity of a known valve, at the relieving pressure (set pressure plus overpressure) using the valve's certified discharge coefficient, as in BS EN ISO 4126-7.
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Pump Power
Calculate pump shaft power from flow rate, total head, and efficiency — or back-calculate flow rate or total head from a known shaft power.
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Water Hammer
Calculate the pressure surge caused by water hammer using the Joukowsky equation, and determine the minimum safe valve closure time to limit the surge within acceptable bounds.
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Expansion Vessel Sizing
Calculate the minimum expansion vessel volume for a sealed hot or chilled water system to BS EN 12828, from system volume, fluid expansion, vessel pre-charge pressure and safety valve setting, including the water reserve.