Chemical Engineering Calculators and Formulas

Chemical Engineering Formulas and Calculators

• Ideal Gas Law Calculator

  P V = n R T

  P absolute pressure, V volume, n amount of gas, T absolute temperature, R = 8.314462618 J/(mol·K)

  Example: 1 mol at 0 °C and 101.325 kPa occupies 22.414 L.

  Open the ideal gas law calculator →

• Reynolds Number Calculator

  Re = ρ v D ÷ μ = v D ÷ ν

  ρ density, v velocity, D pipe diameter, μ dynamic viscosity, ν kinematic viscosity

  Example: Pipe flow is laminar below Re ≈ 2300 and turbulent above about 4000.

  Open the reynolds number calculator →

• Pipe Pressure Drop Calculator

  ΔP = f (L ÷ D) (ρ v² ÷ 2)

  f Darcy friction factor (64/Re laminar, Colebrook–White turbulent), L pipe length, D inside diameter, ρ density, v mean velocity

  Example: Darcy–Weisbach with the Colebrook friction factor.

  Open the pipe pressure drop calculator →

• SCFM to ACFM Calculator

  Q_act = Q_std × (T_act ÷ T_std) × (P_std ÷ P_act)

  Q gas flow, T absolute temperature, P absolute pressure

  Example: 100 SCFM at 100 psig and 68 °F = 12.82 ACFM.

  Open the scfm to acfm calculator →

• Bubble Point Pore Size Calculator

  d = 4 k γ cos θ ÷ ΔP

  d pore size, k pore shape factor, γ surface tension, θ contact angle, ΔP bubble-point pressure

  Example: 30 psi with isopropyl alcohol gives 0.42 µm (k = 1).

  Open the bubble point pore size calculator →

• Corrosion Rate Calculator

  CR = K W ÷ (A T D)

  W mass loss, A exposed area, T exposure time, D density, K unit constant (8.76 × 10⁴ for mm/y)

  Example: 25 mg lost from 20 cm² of steel in 720 h = 0.0193 mm/y.

  Open the corrosion rate calculator →

Unit Converters for Chemical Engineering

• Pressure Converter – Pa, kPa, psi, bar, inH₂O, mmHg, torr, atm
• Flow Rate Converter – CFM, m³/h, L/min, L/s, GPM, sccm, SLPM
• Density Converter – kg/m³, g/cm³, g/mL, lb/ft³, lb/gal, mg/L
• Dynamic Viscosity Converter – Pa·s, mPa·s, cP, P, lbf·s/ft²
• Kinematic Viscosity Converter – m²/s, mm²/s, cSt, St, ft²/s
• Temperature Converter – °C, °F, K, °R
• Heat Transfer Coefficient Converter – W/(m²·K), BTU/(h·ft²·°F), kcal/(h·m²·°C), U-value
• Thermal Conductivity Converter – W/(m·K), mW/(m·K), BTU/(h·ft·°F), k-value, kcal/(h·m·°C)
• Volume Converter – L, mL, m³, ft³, in³, US gal, imp gal
• Weight and Mass Converter – kg, g, mg, lb, oz, st, t, ton, oz t, ct
• Mesh to Micron Converter – US sieve number (mesh) ↔ opening in µm, mm and inches, with the full ASTM E11 table.

Common Chemical Engineering Conversions

• pascal to psi
• psi to pascal
• cubic foot per minute to cubic meter per hour
• cubic meter per hour to cubic foot per minute
• gram per cubic centimeter to kilogram per cubic meter
• kilogram per cubic meter to gram per cubic centimeter
• centipoise to pascal-second
• pascal-second to centipoise
• centistokes to square millimeter per second
• square millimeter per second to centistokes
• Celsius to Fahrenheit
• Fahrenheit to Celsius

Using these chemical engineering calculators

Process calculations usually start with the state of a gas or liquid and then move to how it flows. The ideal gas law relates pressure, volume, amount and temperature; the Reynolds number tells you whether pipe flow is laminar or turbulent; and the Darcy–Weisbach calculator turns flow rate, pipe size and roughness into a pressure drop.

Gas flows need particular care because a cubic metre of gas is not a fixed amount of gas. Standard flow (SCFM, Nm³/h) refers to fixed reference conditions, while actual flow (ACFM, m³/h) is the volume at line pressure and temperature. Mixing the two, or mixing reference conditions such as 0 °C and 15 °C, can shift results by several percent.

For membranes, filters and powders, the bubble-point and mesh-to-micron tools translate test readings into pore and particle sizes. The corrosion-rate calculator follows ASTM G1 mass-loss practice, so the units of mass, area, time and density must match the method.