PSI to GPM 技術索引

プロジェクト概要

工学計算の透明性と流体力学規格

給排水衛生設備、消火設備配管、産業流体回路のための独立系工学リファレンスです。

Why we built this platform

A common misconception in piping, irrigation, and field mechanics is that a single pressure gauge reading (PSI or Bar) directly dictates how much water (GPM or L/min) will be delivered. In reality, static pressure is merely potential energy; actual volumetric flow rate depends on internal conduit geometry, pipe surface friction, elevation change, and downstream pressure drop.

Many online calculators treat fluid mechanics as an opaque "black box," omitting the formulas used, assuming arbitrary pipe schedules, or ignoring practical velocity thresholds. PSI to GPM was created to provide engineers, technicians, contractors, and facility managers with transparent calculators displaying explicit formulas, verifiable engineering constants, dual Metric and US Customary units, and practical field limits.

Governing technical standards & references (JA)

Our calculation models and technical documentation cite consensus fluid mechanics references and recognized regional standards:

Our editorial and calculation methodology

Every tool published on PSI to GPM adheres to four strict engineering principles:

  1. Explicit Physical Models: We clearly identify whether a calculation utilizes empirical approximations (such as Hazen-Williams for water distribution) or exact rational mechanics (such as Darcy-Weisbach with Colebrook-White friction factors).
  2. Published Mathematical Constants: Dimensional constants (e.g., 4.52 for Hazen-Williams PSI loss; 29.83 for hydrant discharge coefficients) are shown with their dimensional units and derivations.
  3. Dimensionally Accurate Internal Diameters: Calculations distinguish nominal pipe sizes from true internal diameters (ID). For example, a 1-inch Schedule 40 PVC pipe has an actual ID of 1.049 inches, yielding substantially different friction losses than nominal dimensions.
  4. Transparent Limitations & Velocity Safeguards: We highlight erosion thresholds (such as the 5 ft/s limit for domestic copper hot water and 8 ft/s for PVC) and water hammer risks.

Read our full Editorial & Calculation Methodology Policy for in-depth information on our review processes, computational guarantees, and AI usage standards.

Professional engineering disclaimer

All calculators, graphs, tables, and reference materials on PSI to GPM are intended strictly for educational, scoping, field troubleshooting, and preliminary engineering assessment. They do not constitute certified engineering plans, stamped construction drawings, or life-safety submittals. Critical municipal infrastructure, high-hazard fire sprinkler networks, and commercial boiler/pump systems must always be designed, verified, and stamped by a licensed Professional Engineer (PE) and approved by the local Authority Having Jurisdiction (AHJ).

Editorial inquiries, errata & corrections

If you identify a numerical discrepancy, a typo in a derivation, or an updated standard revision, please contact us via our Contact page. We verify all technical feedback against primary engineering references and document all resolved discrepancies publicly in our Calculation Errata & Updates Log.