Fluid Properties constants

15 values, each with its units, its uncertainty, and where it came from.

Absolute Roughness of Cast Iron Pipe measured

\epsilon_{\mathrm{CI}} = 0.00026\ \text{m}

mAbsolute roughness ε of new uncoated cast iron pipe, about 0.26 mm — five times rougher than steel, and far worse when tuberculated.

\epsilon_{\mathrm{steel}} = 0.000046\ \text{m}

mAbsolute roughness ε of new commercial steel or wrought-iron pipe, 0.046 mm (0.00015 ft) — the Moody-chart default.

\epsilon_{\mathrm{tube}} = 0.0000015\ \text{m}

mAbsolute roughness ε of drawn copper tube, glass and smooth plastic pipe, about 0.0015 mm — 30 times smoother than steel.

K_{w} = 2,180,000,000\ \text{Pa}

PaIsothermal bulk modulus of liquid water at 20 °C and 1 atm, about 2.18 GPa — a 0.005 % volume change per bar of pressure.

\rho_{\mathrm{ice}} = 917\ \text{kg/m}^{3}

kg/m³Density of ordinary hexagonal ice at 0 °C and 1 atm, about 917 kg/m³ — roughly 8 % lighter than the water it freezes from.

\rho_{\mathrm{Hg}} = 13,534\ \text{kg/m}^{3}

kg/m³Density of liquid mercury at 20 °C and 1 atm, 13 534 kg/m³ — 13.5 times water, and the basis of the mmHg pressure unit.

\rho_{\mathrm{sw}} = 1,025\ \text{kg/m}^{3}

kg/m³Representative density of open-ocean seawater at 35 g/kg salinity and 15 °C, about 1025 kg/m³ or 64 lb/ft³ at the surface.

\mu_{\mathrm{air}} = 0.0000181\ \text{Pa}{\cdot}\text{s}

Pa·sDynamic viscosity of dry air at 20 °C and 1 atm, 18.1 µPa·s — about 1/55 of water's, though its kinematic viscosity is 15× larger.

\mu_{\mathrm{SAE30}} = 0.088\ \text{Pa}{\cdot}\text{s}

Pa·sDynamic viscosity of a typical SAE 30 mineral engine oil at 40 °C, roughly 0.088 Pa·s — about 90 times that of water at 20 °C.

\mu_{w} = 0.001002\ \text{Pa}{\cdot}\text{s}

Pa·sDynamic viscosity of pure water at 20 °C and 1 atm, 1.002 mPa·s — the value that made the centipoise a de facto standard.

C_{\mathrm{CI}} = 100\ \text{—}

—Hazen-Williams roughness coefficient for aged unlined cast iron pipe, typically 100 — new pipe is near 130, badly tuberculated near 60.

C_{\mathrm{PVC}} = 150\ \text{—}

—Hazen-Williams roughness coefficient for smooth plastic pipe such as PVC, PE and CPVC, conventionally taken as 150 for design.

n_{\mathrm{concrete}} = 0.013\ \text{—}

—Manning roughness coefficient for finished concrete channels and pipe, typically 0.013 with a defensible range of 0.011 to 0.016.

\alpha_{\mathrm{PVC}} = 0.000054\ \text{1/K}

1/KLinear expansion coefficient of rigid PVC pipe, about 54 µm/(m·K) or 3.0 µin/(in·°F) — nearly five times that of steel.

p_{v} = 2,339\ \text{Pa}

PaSaturation vapour pressure of water at 20 °C, 2339 Pa (0.339 psia) — the absolute pressure at which 20 °C water boils.