Pound per square inch

The kilopound per square inch (ksi) is a scaled unit derived from psi, equivalent to a thousand psi (1000 lbf/in2). ksi are not widely used for gas pressures. They are mostly used in materials science, where the tensile strength of a material is measured as a large number of psi. The conversion in SI units is 1 ksi = 6.895 MPa, or 1 MPa = 0.145 ksi. The megapound per square inch (Mpsi) is another multiple equal to a million psi. It is used in mechanics for the elastic modulus of materials, especially for metals. The conversion in SI units is 1 Mpsi = 6.895 GPa, or 1 GPa = 0.145 Mpsi. == Magnitude ==

• Inch of water: 0.036 psid • Blood pressure – clinically normal human blood pressure (120/80 millimetre of mercury (mmHg)): 2.32 psig/1.55 psig • Natural gas residential piped in for consumer appliance; 4–6 psig. • Boost pressure provided by an automotive turbocharger (common): 6–15 psig • NFL football: 12.5–13.5 psig • Atmospheric pressure at sea level (standard): 14.7 psia • Automobile tire overpressure (common): 32 psig • Bicycle tire overpressure (common): 65 psig • Workshop or garage air tools: 90 psig • Railway air brakes or road brakes reservoir overpressure (common): 90–120 psig • Road racing bicycle tire overpressure: 120 psig • Steam locomotive fire tube boiler (UK, 20th century): 150–280 psig • Union Pacific Big Boy steam locomotive boiler: 300 psig • US Navy steam boiler pressure: 800 psi • Natural gas pipelines: 800–1,000 psig • Full SCBA (self-contained breathing apparatus) for IDLH (non-fire) atmospheres: 2,216 psig • Nuclear reactor primary loop: 2300 psi • Full SCUBA (self-contained underwater breathing apparatus) tank overpressure (common): 3,000 psig • Full SCBA (self-contained breathing apparatus) for interior firefighting operations: 4,500 psig • Airbus A380 hydraulic system: 5,000 psig • Land Rover Td5 diesel engine fuel injection pressure: 22,500 psi • Ultimate tensile strength of ASTM A36 steel: 58,000 psi • Water jet cutter: 40,000–100,000 psig == Conversions ==

The conversions to and from SI are computed from exact definitions but result in a repeating decimal. \begin{align} 1 \, \mathrm{lbf / in ^ 2} & = \frac{(0.453\,592\,37 \, \mathrm{kg} \times 9.806\,65 \, \mathrm{m / s ^ 2}) / \mathrm{lbf}}{(0.0254 \, \mathrm{m / in}) ^ 2} \, \mathrm{lbf / in ^ 2} \\ & = \frac{8896\,443\,230\,521}{1290\,320\,000} \, \mathrm{Pa} \\ & \approx 6894.757 \, \mathrm{Pa} \\ 1 \, \mathrm{Pa} & = \frac{1290\,320\,000}{8896\,443\,230\,521} \, \mathrm{lbf / in ^ 2} \\ & \approx 0.000\,145\,0377 \, \mathrm{lbf / in ^ 2} \\ 1 \, \mathrm{kPa} & \approx 0.\,145\,0377 \, \mathrm{lbf / in ^ 2} \\ \end{align} Approximate conversions (rounded to some arbitrary number of digits, except when denoted by "≡") are shown in the following table. == See also ==