Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

This is an AMP page - Open full page! for all features.

STP - Standard Temperature and Pressure and NTP - Normal Temperature and Pressure

The definition of STP - Standard Temperature and Pressure and NTP - Normal Temperature and Pressure.

Sponsored Links

Since temperature and air pressure varies from place to place a standard reference is necessary for comparing the testing and the documentation of chemical and physical processes.

Note! There is a variety of alternative definitions for standard reference conditions of temperature and pressure. STP, NTP and other definitions should therefore be used with care. It is always important to know the reference temperature and reference pressure for the actual definition used.


STP - Standard Temperature and Pressure

STP is commonly used to define standard conditions for temperature and pressure which is important for the measurements and documentation of chemical and physical processes:

  1. STP - Standard Temperature and Pressure - is defined by IUPAC (International Union of Pure and Applied Chemistry) as air at 0 oC (273.15 K, 32 oF) and 105 pascals (1 bar).

  2. STP - commonly used in the Imperial and USA system of units - as air at 60oF (520oR, 15.6oC) and 14.696 psia (1 atm,  1.01325 bara)
    • also named "1 Standard Atmosphere"
    • At these conditions, the volume of 1 mol of a gas is 23.6442 liters.
    • These conditions are the most commonly used to define the volume term Sm3 (Standard cubic meter)

Note! The earlier IUAPC definition of STP to 273.15 K and 1 atm (1.01325 105 Pa) is discontinued.  However,

    • These conditions are still the most commonly used to define the volume term Nm3 (Normal cubic meter) 
    • At these conditions, the volume of 1 mol of a gas is 22.4136 liters.

1 Pa = 10-6 N/mm2 = 10-5 bar = 0.1020 kp/m2 = 1.02x10-4 m H2O = 9.869x10-6 atm = 1.45x10-4 psi (lbf/in2)

NTP - Normal Temperature and Pressure

NTP is commonly used  as a standard condition  for testing and documentation of fan capacities:

  • NTP - Normal Temperature and Pressure - is defined as air at 20oC (293.15 K, 68oF) and 1 atm (101.325 kN/m2, 101.325 kPa, 14.7 psia, 0 psig, 29.92 in Hg, 407 in H2O, 760 torr). Density 1.204 kg/m3 (0.075 pounds per cubic foot)
    • At these conditions, the volume of 1 mol of a gas is 24.0548 liters.

    Example - Fan Pressure Increase

    A fan that produce a static pressure of 3 in H2O (a good average value) - will increase the absolute air pressure by

    ((3 in H2O) / (407 in H2O)) (100 %) = 0.74 %

    SATP - Standard Ambient Temperature and Pressure

    SATP - Standard Ambient Temperature and Pressure is also used in chemistry (International Union of Pure and Applied Chemistry - IUPAC) as a reference:

    • SATP - Standard Ambient Temperature and Pressure is a reference with temperature of 25oC (298.15 K) and pressure of 100.000 kPa.
      • At these conditions, the volume of 1 mol of a gas is 24.4651 liters.


    ISA - International Standard Atmosphere

    ISA - International Standard Atmosphere is used as a reference to aircraft performance:

    • ISA - International Standard Atmosphere is defined to 101.325 kPa, 15oC and 0% humidity.


    ICAO Standard Atmosphere

    Standard model of the atmosphere adopted by the International Civil Aviation Organization (ICAO):

    • Atmospheric pressure: 760 mmHg = 14.7 lbs-force/sq inch
    • Temperature: 15oC = 288.15 K = 59oF
    Sponsored Links

    Related Topics

    Related Documents

    Sponsored Links

    Share

    Search Engineering ToolBox

    • the most efficient way to navigate the Engineering ToolBox!

    SketchUp Extension - Online 3D modeling!

    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!

    Privacy

    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.

    Google use cookies for serving our ads and handling visitor statistics. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected.

    AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information.

    Topics

    Unit Converters

    Temperature

    oC
    oF


    Load Calculator!

    Length

    m
    km
    in
    ft
    yards
    miles
    naut miles


    Load Calculator!

    Area

    m2
    km2
    in2
    ft2
    miles2
    acres


    Load Calculator!

    Volume

    m3
    liters
    in3
    ft3
    us gal


    Load Calculator!

    Weight

    kgf
    N
    lbf


    Load Calculator!

    Velocity

    m/s
    km/h
    ft/min
    ft/s
    mph
    knots


    Load Calculator!

    Pressure

    Pa (N/m2)
    bar
    mm H2O
    kg/cm2
    psi
    inches H2O


    Load Calculator!

    Flow

    m3/s
    m3/h
    US gpm
    cfm


    Load Calculator!

    3 10

    This website use cookies. By continuing to browse you are agreeing to our use of cookies! Learn more