Airside: Duct & Psychrometrics

Enter 4,650 m³/h and get the round Ø500 and rectangular 600×350 duct that carry it at the same friction. Type in diffuser velocities and it shows which damper to throttle. A field notebook for HVAC techs. No sign-up, no ads, no internet. Data stays on this phone. One backup file moves it all to a new phone. Duct sizing and pressure drop, psychrometric state points, and room loads, calculated on the spot. Keep duct tables, air states, and diffuser readings per job, then export a PDF. ■ Please read first · Not a substitute for design documents or a certified TAB report. It uses published formulas and shows its work. · Units are metric: m³/h, Pa, mm, °C (CMM and L/s shown alongside). No CFM or in. w.g. input. · Formulas are public ASHRAE Handbook Fundamentals equations: Colebrook friction factor (Altshul–Tsal cross-check), Huebscher equivalent diameter, Chapter 1 psychrometrics. · Roughness, fitting loss coefficients, load per area, atmospheric pressure, velocity and aspect-ratio warnings, and standard round sizes are editable defaults with source and date. Values not yet checked against the original tables are marked "Needs check". One tap restores defaults. · Fitting loss defaults are a starting point; use manufacturer or ASHRAE fitting data. · Room load is a peak estimate at one summer and one winter design condition. It is not an hourly load calculation or energy analysis. · The airflow sheet helps you record and judge readings. It is not a certified TAB report. · No refrigerant, piping, duct strength, or noise calculations. · No account, no server, no permissions. ■ Duct: equal friction, velocity, size · Equal friction: airflow and target friction (Pa/m) give the diameter, standard round size, and rectangular sizes (by aspect ratio or fixed ceiling-space height) · Velocity method, size-to-friction check, fittings loss total · Equivalent diameter, aspect ratio, velocity warnings · Calculation trail: Re, friction factor, and loss as equations with real numbers, to check by hand · Target friction worked back from fan external static ■ Air: state points, mixing, condensation · Dry-bulb plus RH, wet-bulb, or dew point gives humidity ratio, enthalpy, dew point, wet-bulb, specific volume, density · Condensation check against dew point · Points and lines plotted on a psychrometric chart ■ Room load · Floor area, wall and window area by orientation, roof, glazing, shading, people, lighting, equipment, outdoor air · Peak cooling and heating load (kW · BTU/h · tons · kcal/h), sensible and latent, W/m², supply airflow, with heat sources shown as a bar ■ Airflow measurement (TAB) · Per diffuser or grille: design airflow and several velocity readings (average × effective area Ak), or a flow hood value · Percent of design with a tolerance verdict (default ±10%, editable) · Proportional balancing order: lowest outlet as reference, others as a multiple of it, with "throttle" or "open more" guidance ■ Jobs For each job (building, floor, system), enter duct sections from fan to terminal. Each gets size, velocity, friction, and fitting loss; main-run static pressure is totaled and drawn as a single-line diagram. Air states, room loads, and airflow readings are saved to the same job. "Duplicate" starts a similar floor. ■ PDF and CSV Save or send an A4 PDF with the main-run drawing, section table, air states and chart, room load, airflow sheet, and the reference values used. CSV opens in Excel. ■ Text size Four steps in "More". ■ First launch A sample job (3rd-floor office supply duct, main-run static 57.7 Pa) is included. "Delete sample" removes it. ■ Backup and contact Export jobs and reference values to one file and restore on a new phone. Backups from other apps are rejected. Questions: "Contact" in the app. ■ Who it's for HVAC and duct designers · duct installers · TAB technicians · building inspectors and facility maintenance. No ads. No in-app purchases. Buy once, done.

· Now available in 8 languages. Units, currency and dates follow your region.