Pump Engineering Reference: Units, Conversions, Fluid Properties, Pipe Data, and Standards

How to Use This Reference

Each table on this page corresponds to a specific calculation elsewhere on this site—friction loss, NPSH, TDH, and pipe sizing all draw on the values below. Where a table’s values are used inside one of the site’s calculators, that calculator is linked directly beneath the table. All values here are cross-checked against standard engineering references (Crane TP-410, Cameron Hydraulic Data, ASHRAE, and the cited standards below); where a value is commonly quoted as a range rather than a single number, the range is shown, since actual material and fluid properties vary with manufacturing tolerance, age, and exact formulation.

Unit Conversion Tables

Flow Rate

Head and Pressure

Note: the ft-of-water ↔ psi conversion depends slightly on the fluid’s temperature and specific gravity (water density varies with temperature—see the Water Properties table below). The 2.3086 factor (commonly rounded to 2.31) assumes water at approximately 60°F and SG = 1.0; for other fluids or temperatures, divide by the actual specific gravity.

Power

Viscosity

Temperature

$$°F = (°C \times \tfrac{9}{5}) + 32 \qquad °C = (°F – 32) \times \tfrac{5}{9} \qquad K = °C + 273.15$$

Use the Flow Unit Converter · Use the Pressure Unit Converter · Use the Head ↔ Pressure Converter · Use the HP ↔ kW Converter

Water Properties by Temperature

Density, vapor pressure, and dynamic viscosity of water at atmospheric pressure. These values are the basis for every NPSH and friction-loss calculation involving water or water-based fluids at non-standard temperatures—vapor pressure in particular is the value most often overlooked when checking NPSH on a hot-water or steam-condensate application.

Critical NPSH note: vapor pressure rises steeply and non-linearly with temperature—it roughly quadruples between 60°F and 140°F. A pump correctly sized for cold water NPSH can cavitate on the same piping at elevated temperature purely from this effect. Always look up vapor pressure at the actual operating temperature, not at 60°F “for simplicity.”

Use the Water Properties Lookup Calculator — interpolates between these values automatically.

Steel Pipe Schedule Chart

Nominal pipe size (NPS), outside diameter (OD), and wall thickness/inside diameter (ID) for Schedule 40 and Schedule 80 steel pipe—the two most common schedules in pump piping.

Why ID matters more than nominal size: friction loss and velocity calculations depend on actual inside diameter, not the nominal size stamped on the pipe. A “2-inch” Schedule 80 pipe has a meaningfully smaller bore (1.939 in) than a “2-inch” Schedule 40 pipe (2.067 in)—always pull the actual ID for the specific schedule in use before calculating velocity or friction loss.

Use the Pipe Schedule Lookup Calculator · Use the Pipe Size & Velocity Calculator

Pipe Roughness Values

Absolute roughness (ε) values used in the Darcy-Weisbach friction factor calculation (Colebrook or Swamee-Jain equations). These are representative values for new or reasonably well-maintained pipe—roughness increases with age, scaling, and corrosion, sometimes substantially.

Aged pipe caution: commercial steel pipe in older potable water or process service can develop roughness several times its new-pipe value due to scaling and tuberculation. For systems with pipe older than roughly 15–20 years and no internal lining, consider using an aged-pipe roughness estimate or verifying with a field friction test rather than relying solely on new-pipe values.

Use the Friction Loss Calculator (Darcy-Weisbach) — includes this roughness table as a built-in material selector.

Hazen-Williams C Values

C-factors for the Hazen-Williams friction loss equation, shown for both new pipe and a typical aged/design value that accounts for expected roughening over service life.

Why the “design” column matters: using new-pipe C values for a system’s entire service life systematically understates friction losses as the pipe ages. Most municipal and industrial design practice uses the lower “design” value specifically to build in margin for the pipe’s expected condition partway through its service life—this is a deliberate design choice, not a measurement of any single point in time.

Use the Friction Loss Calculator (Hazen-Williams) — includes a built-in Darcy-Weisbach comparison to flag when Hazen-Williams may not be the appropriate method (see the validity limits noted in the System Design).

K-Factor Table for Valves and Fittings

Representative resistance coefficients (K) for common valves and fittings, used to calculate minor (fitting) losses: $h_f = K \times \dfrac{v^2}{2g}$. Actual K values vary by manufacturer, size, and specific design—treat these as planning-level estimates and consult the manufacturer’s data for final design on critical applications.

Use the K-Factor & Equivalent Length Calculator — sums multiple fittings automatically for a full suction or discharge line minor-loss calculation.

Specific Gravity and Viscosity of Common Fluids

Representative values at approximately 60–68°F (15.6–20°C) unless otherwise noted. Both specific gravity and viscosity are strongly temperature-dependent for most non-aqueous fluids—these figures are starting points, not substitutes for the actual fluid’s data sheet.

Glycol note: propylene and ethylene glycol/water mixtures (common in HVAC hydronic freeze protection) change specific heat, density, and viscosity depending on concentration—see the HVAC Hydronic Pump Sizing calculator for a built-in glycol correction rather than using pure-glycol values for a mixed solution.

Atmospheric Pressure by Altitude

Standard atmospheric pressure decreases with elevation, directly reducing available NPSH for any suction-lift application. These values follow the standard barometric formula and represent typical conditions—actual local barometric pressure varies with weather and should be used for precision work.

Why this matters for sizing: a well pump or booster system designed at sea level and then installed at 5,000 ft elevation loses roughly 2.5 psi (about 5.8 ft of head) of available NPSH purely from the altitude change—enough, on a marginal design, to push a previously adequate system into cavitation. Always use the actual site elevation, not sea-level assumptions, in any NPSH calculation.

Use the NPSH Available Calculator — includes this altitude table as a built-in lookup.

Pump Standards Explained

A plain-language guide to the standards referenced throughout this site’s calculators and articles.

A frequent point of confusion: API 610 and ASME B73.1 are sometimes discussed as if they were competing options for the same decision, but they answer different questions—B73.1 standardizes dimensions and interchangeability; API 610 specifies construction robustness and testing rigor for severe service. A pump can, and often does, meet both simultaneously depending on the application.

Related Calculators and Further Reading

Recommended Calculators on PumpCalcs.com

• Flow Unit Converter · Pressure Unit Converter · HP ↔ kW Converter · Head ↔ Pressure Converter
• Water Properties Lookup — interpolated density, vapor pressure, and viscosity at any temperature.
• Pipe Schedule Lookup — full schedule and dimension lookup beyond the abbreviated table above.
• Friction Loss Calculator (Darcy-Weisbach) and Friction Loss Calculator (Hazen-Williams) — both draw directly on the roughness and C-value tables above.
• K-Factor & Equivalent Length Calculator
• NPSH Available Calculator — includes the altitude and water vapor-pressure tables as built-in lookups.

Primary Sources

• Crane Technical Paper 410 (TP-410): Flow of Fluids Through Valves, Fittings, and Pipe. The standard industry reference for K-factors and friction methodology.
• Cameron Hydraulic Data Book (Flowserve): pipe, fluid property, and general hydraulic reference tables.
• ASME B36.10 / B36.19: Welded and Seamless Wrought Steel Pipe / Stainless Steel Pipe—source standards for the pipe schedule dimensions above.
• NIST / ASHRAE steam and water property tables: source basis for the water properties table above.
• U.S. Standard Atmosphere (1976): basis for the altitude-pressure table.

Verification and Disclaimer

Data verification: All tables on this page are cross-checked against at least two independent published sources (Crane TP-410, Cameron Hydraulic Data, ASME pipe standards, and standard steam/water property tables) as part of this site’s verification protocol. Where a property varies by manufacturer, formulation, or specific test condition, a representative range is shown rather than a false single-value precision.

Recommended use: These tables are suitable for preliminary design, estimation, and educational use. For final design, procurement specifications, or code-compliance documentation, verify current values against the specific manufacturer’s data sheet and the current published edition of the applicable standard—standards are periodically revised, and this page reflects general, commonly-applied guidance rather than a specific edition date.

For corrections or feedback: See the Contact page. If you identify a value that differs from a current authoritative source, please let us know—we verify and publicly log all corrections.

Last updated: July 2026 | Reviewed by: [PE Reviewer Name, [State] PE License [Number]] | Reading time: ~14 minutes