Chemical & Process Calculators
Pumps, pipes, and process fundamentals.
- 4–20 mA Loop ScalingConvert loop current to process value and back — with the burden check.PV = PVlo + (I − 4 mA)/16 mA · span
- Thin-Wall Pressure Vessel StressHoop and longitudinal stress σ = Pr/t, with the r/t > 10 validity gate.σ_hoop = P·r/t σ_long = P·r/2t
- Reynolds NumberRe = ρVL/µ with one-click air or water properties, or your own fluid.Re = ρ·V·L / µ = V·L / ν
- Pipe Pressure Drop (Darcy-Weisbach)Friction loss in a round pipe — Swamee-Jain friction factor, automatic laminar branch.ΔP = f·(L/D)·½ρV², f = 0.25/[log₁₀(ε/3.7D + 5.74/Re^0.9)]² (laminar: f = 64/Re)
- Pipe Flow VelocityMean velocity in a round pipe from volumetric flow and diameter.V = Q / A, A = πD²/4
- Bernoulli Pressure ChangeDownstream pressure from an upstream state, two velocities, and an elevation change.p₁ + ½ρv₁² + ρgz₁ = p₂ + ½ρv₂² + ρgz₂
- Orifice FlowFlow through a sharp-edged orifice from a pressure differential — Q = C_d·A·√(2ΔP/ρ).Q = C_d · A · √(2·ΔP/ρ)
- Manning Open-Channel FlowDischarge in a rectangular channel from geometry, slope, and roughness n.Q = (1/n) · A · R^(2/3) · S^(1/2) (SI units; R = A/P)
- Pump Hydraulic & Shaft PowerWater power from flow and head, and the shaft power once efficiency takes its cut.P_hyd = ρ·g·Q·H P_shaft = P_hyd / η
- NPSH AvailableNet positive suction head at the pump inlet — the cavitation margin.NPSHa = (P_surface − P_vapor)/(ρ·g) + z_static − h_friction
- SCFM ⇄ ACFMStandard-to-actual airflow via the ideal-gas temperature and pressure correction.ACFM = SCFM · (P_std / P_act) · (T_act / T_std) (T absolute)
- Water Hammer (Joukowsky)Pressure surge from a sudden velocity change: ΔP = ρ·a·Δv.ΔP = ρ · a · Δv (valid when closure time < 2L/a)
- Pressure ConverterPa, kPa, bar, psi, atm, mmHg, inH₂O, and Torr — one value, every dialect.1 atm = 101,325 Pa 1 psi = 6,894.757 Pa 1 bar = 10⁵ Pa
- Volumetric Flow ConverterL/s, L/min, m³/h, US GPM, and CFM — pump curves to duct specs.1 GPM(US) = 3.785412 L/min 1 CFM = 1.699011 m³/h
- Horizontal Tank VolumePartial-fill volume of a horizontal cylindrical tank from the dip level.A = r²·cos⁻¹((r−h)/r) − (r−h)·√(2rh−h²) V = A·L
- Vertical Tank VolumeFill volume of a vertical cylindrical tank from the level.V = (π/4)·D²·h
- Ideal Gas Law (PV = nRT)Leave any one of P, V, n, T blank — the card solves for it.PV = nRT (R = 8.3145 kPa·L·mol⁻¹·K⁻¹)
- Gas DensityDensity of a gas from pressure and temperature — ρ = PM/RT.ρ = P·M / (R·T)
- Log-Mean Temperature DifferenceLMTD for counterflow or parallel-flow heat exchangers from the four terminal temperatures.LMTD = (ΔT₁ − ΔT₂) / ln(ΔT₁/ΔT₂)
- Heat Exchanger DutyQ = ṁ·cp·ΔT for one stream — the first number of every exchanger problem.Q = ṁ · cp · ΔT
- Heat Conduction (Fourier)Steady heat flow through a flat layer — Q = k·A·ΔT/L.Q = k · A · ΔT / L
- Dilution (C₁V₁ = C₂V₂)Leave any one of the four blank — stock, dose, or final volume solved.C₁ · V₁ = C₂ · V₂
- Pump Head ⇄ PressureConvert a pressure to metres of head for a fluid, plus static lift.H = P / (ρ·g) + z (ρ = SG × 1000 kg/m³)
- Arrhenius Rate RatioHow much faster a reaction runs at a new temperature, from the activation energy.k₂/k₁ = exp[ (Ea/R) · (1/T₁ − 1/T₂) ]
- Half-Life DecayFraction remaining after any elapsed time, from the half-life.N/N₀ = 2^(−t/t½) = e^(−λt), λ = ln 2 / t½
- Dew Point & Absolute HumidityDew point from temperature and relative humidity — Magnus formula, plus g/m³ of water.Td = b·γ / (a − γ), γ = ln(RH/100) + a·T/(b+T) (a = 17.625, b = 243.04)