A = area (in2, ft2, m2)
1) In the Imperial - English Engineering System special care must be taken for the force unit. The basic unit for mass is slug and the unit for force is pound (lb) or pound force (lbf).
The absolute pressure - pabs - is measured relative to the absolute zero pressure - the pressure that would occur at absolute vacuum. All calculations involving the gas law requires pressure (and temperature) to be in absolute units.
A gauge is often used to measure the pressure difference between a system and the surrounding atmosphere. This pressure is often called the gauge pressure and can be expressed as
pg = ps - patm (2)
pg = gauge pressure (Pa, psi)
ps = system pressure (Pa, psi)
patm = atmospheric pressure (Pa, psi)
Atmospheric pressure is the pressure in the surrounding air at - or "close" to - the surface of the earth. The atmospheric pressure varies with temperature and altitude above sea level.
The Standard Atmospheric Pressure (atm) is normally used as the reference when listing gas densities and volumes. The Standard Atmospheric Pressure is defined at sea-level at 273oK (0oC) and is 1.01325 bar or 101325 Pa (absolute). The temperature of 293oK (20oC) is sometimes used.
In imperial units the Standard Atmospheric Pressure is 14.696 psi.
Since 1 Pa is a small pressure unit the unit hectoPascal (hPa) is widely used, especially in meteorology. The unit kiloPascal (kPa) is commonly used in the design of technical applications - like HVAC systems, piping systems and similar.
A torr (often used in vacuum applications) is named after Torricelli and is the pressure produced by a column of mercury 1 mm high - equals to 1 / 760th of an atmosphere.
Pounds per square inch (psi) was commonly used in the U.K. but is now replaced in almost every country except in the US by SI units. Since atmospheric pressure is 14.696 psi - a column of air on a area of one square inch area from the Earth's surface to the space - weights 14.696 pounds.
The bar (bar) is commonly used in the industry. One bar is 100,000 Pa, and for most practical purposes can be approximated to one atmosphere even if
1 bar = 0.9869 atm = 14.5 psi
There are 1000 millibar (mbar) in one bar, a unit common in meteorology and weather applications.
1 millibar = 0.001 bar = 0.750 torr = 100 Pa
Download kPa to bar, psi, mmH2O and inH2O chart
- free apps for offline use on mobile devices.
The SI-system, unit converters, physical constants, drawing scales and more.
The study of fluids - liquids and gases. Involving velocity, pressure, density and temperature as functions of space and time.
Air, LNG, LPG and other common gas properties, pipeline capacities, sizing of relief valves.
Instrumentation and process control systems - design and documentation.
Pressure ratings of ABS 1208, ABS 1210, ABS 1316 and ABS 2112.
Chemical, physical and thermal properties of acetone, also called 2-propanone, dimethyl ketone and pyroacetic acid. Phase diagram included.
Figures and tables with isobaric (Cp) and isochoric (Cv) specific heat of air at constant temperature and pressure ranging 0.01 to 10000 bara.
Elevation above sea level - in feet and meter - with barometric and atmospheric pressure - inches mercury, psia, kg/cm2 and kPa.
Elevation compensating manometer.
Chemical, physical and thermal properties of benzene, also called benzol. Phase diagram included.
Isothermal and isentropic gas compression and expansion processes.
Duct systems are commonly divided into three pressure classifications.
Pascal's law and the hydraulic force acting in fluids.
Depth and hydrostatic pressure.
International standard atmosphere in elevation -2000 to 30000 metre - pressure, temperature, density, viscosity, thermal conductivity and velocity of sound.
Calculate the potential of pressure energy in a incompressible fluid.
Pressure vs. head units - like lb/in2, atm, inches mercury, bars, Pa and more.
Convert between pressure units like Pa, bar, atmosphere, pound square feet, psi and more.
Convert from kPa to psi and inches of Water and Mercury.
An introduction to the SI metric system.
The amount of flash steam generated depends on steam pressure and pressure in the condensate lines.
Calculate pressure drops in steam distribution pipe lines.
Properties of the US standard atmosphere ranging -5000 to 250000 ft altitude.
Common converting units for Acceleration, Area, Density, Energy, Energy per unit mass, Force, Heat flow rate, Heat flux, Heat generation per unit volume and many more.
Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!
We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.
Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.