Search results
Results From The WOW.Com Content Network
The pound per square inch (abbreviation: psi) or, more accurately, pound-force per square inch (symbol: lbf/in 2), [1] is a unit of measurement of pressure or of stress based on avoirdupois units and used primarily in the United States. It is the pressure resulting from a force with magnitude of one pound-force applied to an area of one square ...
In practical engineering applications for cylinders (pipes and tubes), hoop stress is often re-arranged for pressure, and is called Barlow's formula. Inch-pound-second system (IPS) units for P are pounds-force per square inch (psi). Units for t, and d are inches (in). SI units for P are pascals (Pa), while t and d=2r are in meters (m).
An especially common rental cylinder provided at tropical dive resorts is the "aluminium-S80" which is an aluminum cylinder design with an internal volume of 0.39 cubic feet (11.0 L) rated to hold a nominal volume of 80 cubic feet (2,300 L) of atmospheric pressure gas at its rated working pressure of 3,000 pounds per square inch (207 bar). [9]
For example, if the static compression ratio is 10:1, and the dynamic compression ratio is 7.5:1, a useful value for cylinder pressure would be 7.5 1.3 × atmospheric pressure, or 13.7 bar (relative to atmospheric pressure). The two corrections for dynamic compression ratio affect cylinder pressure in opposite directions, but not in equal strength.
Pressure is a fundamental physical parameter that is defined as force divided by area. The unit of pressure in the modern International System of Units is the pascal (equivalent to the newton per square metre). A chamber pressure measured with a copper crusher gauge would therefore be expressed in MPa (CUP) in the ISU. [clarification needed]
Despite having the dimension of pressure, MEP cannot be measured. [2] When quoted as an indicated mean effective pressure (IMEP), it may be thought of as the average pressure acting on a piston during the different portions of its cycle. When friction losses are subtracted from the IMEP, the result is the brake mean effective pressure (BMEP).
The SI unit for pressure is the pascal (Pa), equal to one newton per square metre (N/m 2, or kg·m −1 ·s −2). This name for the unit was added in 1971; [7] before that, pressure in SI was expressed in newtons per square metre. Other units of pressure, such as pounds per square inch (lbf/in 2) and bar, are also in common use.
Barlow's formula (called "Kesselformel" [1] in German) relates the internal pressure that a pipe [2] can withstand to its dimensions and the strength of its material.. This approximate formula is named after Peter Barlow, an English mathematician.