Math & Numbers

Convert between Brinell (HB), Vickers (HV), and Rockwell (HRC / HRB) hardness via ASTM E140 tabulated data with linear interpolation. Three material classes: carbon/alloy steel (HV 100–960), austenitic stainless (HV 100–600), and cartridge brass (HV 40–200). Any input scale produces all the others; a scale that does not apply in the current hardness band returns 'out of range'. Indicative only — not for acceptance testing per ASTM E140.

Math & Numbers

Calculate Poisson's ratio ν = −ε_transverse / ε_longitudinal and solve any of the three unknowns: ratio, lateral strain, or longitudinal strain. Tensile ε_long > 0 produces lateral contraction ε_lat < 0. Typical values: steel ≈ 0.30, aluminum ≈ 0.33, rubber ≈ 0.49, cork ≈ 0. Theoretical isotropic range 0 ≤ ν ≤ 0.5.

Math & Numbers

Calculate the static safety factor n = σ_limit / σ_applied against yielding (σ_y) or ultimate tensile strength (σ_uts). Built-in typical strengths for carbon/alloy steel, aluminum, copper, austenitic stainless and titanium, plus a custom σ_limit option. Assessment: n<1 failure, 1≤n<1.5 marginal, n≥1.5 safe.

Math & Numbers

Linear and volumetric thermal expansion of an isotropic material. Linear: ΔL = α·L₀·ΔT, L₁ = L₀·(1+α·ΔT). Volumetric: ΔV = 3α·V₀·ΔT (β = 3α for isotropic solids). Built-in typical α for carbon/alloy steel, aluminum, copper, austenitic stainless, titanium and glass, plus custom. ΔT in K or °C, length in mm, volume in mm³.

Math & Numbers

Thermal stress in a fully constrained member under a uniform temperature change: σ_th = E·α·ΔT. Built-in typical Young's modulus E and expansion coefficient α for carbon/alloy steel, aluminum, copper, austenitic stainless and titanium, plus custom values. ΔT in K or °C (same magnitude), result in MPa. Heating (ΔT>0) → compressive stress in the member.

Math & Numbers

Solve Young's modulus (modulus of elasticity) in the linear-elastic region using E = σ/ε (Hooke's law). Three directions: modulus E = σ/ε, stress σ = E·ε, strain ε = σ/E. Pick the unknown, supply the other two positive values. Result in MPa with a GPa reading (e.g. steel ≈ 200 000 MPa).

Math & Numbers

Compute the total, sensible, and latent capacity of an air-handling-unit (AHU) coil from the entering/leaving air state and the dry-air mass flow ṁ_da. Total capacity Qt = ṁ_da·(h1 − h2); sensible capacity Qs = ṁ_da·cp_ma·(T1 − T2) with cp_ma ≈ 1.006 + 1.86·W [kJ/(kg da·K)]; latent capacity Ql = Qt − Qs; Sensible Heat Ratio SHR = Qs / Qt. Each state is described by dry-bulb T plus one humidity input (relative humidity φ, or humidity ratio W); W is derived from the Magnus saturation fit when RH is supplied, and enthalpy h = 1.006·T + W·(2501 + 1.86·T) [kJ/kg da]. Signed result — works for cooling or heating coils.

Math & Numbers

Compute the air change rate (ACH / n) of a room from the outdoor supply airflow Q and the room volume V: n = Q/V (1/h). Three modes: solve ACH (given Q and V), solve airflow (given n and V), or solve volume (given n and Q). Flow in m³/s/m³/h/CFM, volume in m³/ft³/L. Also reports the well-mixed single-zone purge time to reach a target residual fraction ε (default 1%): t = −ln(ε)/n hours.

Math & Numbers

Compute the full set of moist-air (psychrometric) state properties from dry-bulb temperature plus one humidity input (relative humidity φ, wet-bulb temperature, dew-point temperature, or humidity ratio W). Returns humidity ratio W (kg/kg and g/kg), relative humidity φ (%), dew-point, wet-bulb, enthalpy h (kJ/kg dry air), specific volume v (m³/kg dry air), partial vapour pressure P_w, and saturation pressure P_ws. Uses the Magnus saturation-pressure fit; wet-bulb is solved iteratively from the thermodynamic psychrometric equation. Default standard atmosphere 101.325 kPa (adjustable). Temperature in °C/K/°F; all reported temperatures are in °C.

Math & Numbers

Saturated pressure ↔ temperature lookup for common HVAC refrigerants via the Antoine fit ln(P) = A − B/(T_C + C): R-22 (HCFC-22), R-134a (HFC-134a), and R-410A (R-32/R-125 near-azeotropic blend). Coefficients fitted against the ASHRAE Handbook / NIST REFPROP saturation tables. Two modes: solve saturation pressure from temperature, or solve saturation temperature from pressure. Pressure may be absolute or gauge (atmospheric default 1.01325 bar) in bar/MPa/kPa/PSI; temperature in °C/K/°F. Engineering estimate only — does not replace the manufacturer's P-T chart.

Math & Numbers

Split an air-conditioning load into sensible and latent components. Total cooling capacity Qt = ṁ_da·(h1 − h2); sensible capacity Qs = ṁ_da·cp_ma·(T1 − T2) with cp_ma ≈ 1.006 + 1.86·W [kJ/(kg da·K)]; latent capacity Ql = Qt − Qs; Sensible Heat Ratio SHR = Qs / Qt. Entering/leaving states are described by dry-bulb temperature T and humidity ratio W; enthalpy h = 1.006·T + W·(2501 + 1.86·T) [kJ/kg da]. Three modes: full air-state split (T1,W1)→(T2,W2), from Qt & Qs (solve SHR + Ql), or from Qt & SHR (solve Qs, Ql).

Math & Numbers

Compute the thermal comfort indices PMV (Predicted Mean Vote, −3 cold..+3 hot) and PPD (Predicted Percentage Dissatisfied, %) per ISO 7730 / ASHRAE 55, using the Fanger equations. Inputs: air temperature Ta, mean radiant temperature Tr, relative air velocity v_ar, relative humidity φ, metabolic rate M (met; 1 met = 58.2 W/m²), clothing insulation Icl (clo; 1 clo = 0.155 m²·K/W), and external work W (defaults to 0). The clothing surface temperature Tcl is solved iteratively. Returns a 7-level ASHRAE sensation label.