In 1999, the International Union of Pure and Applied Chemistry (IUPAC) said that for the purposes of specifying the properties of substances, “the standard pressure” should be defined as precisely 100 kPa (≈750.01 torr) or 29.53 inHg rather than the 101.325 kPa value of “one standard atmosphere” (From Wikipedia).
I think we're talking about 2 different things here, the Standard Atmosphere and the International Standard Atmosphere. I know the latter is purely a set of units set up to calibrate and test things worldwide to the same standard. 15C, 1 Atmosphere of 1013,25 hPa. It's heavily used in the aerospace industry for calibration and performance. Everyone has to be on the same page for these two items. A bit more research is needed. Mike Payne On 04/09/2011, at 07:39 , John M. Steele wrote: > One (standard) atmosphere is 101.325 kPa. However, properties for many > chemicals are specified at 1 bar (100 kPa) rather than 1 atm. There is also > a 'technical atmosphere" 98.0665 kPa (based on kilogram-force), which is now > deprecated and rarely used.. > > --- On Sun, 9/4/11, Michael Payne <[email protected]> wrote: > > From: Michael Payne <[email protected]> > Subject: [USMA:51064] Re: planes collide > To: "U.S. Metric Association" <[email protected]> > Date: Sunday, September 4, 2011, 6:58 AM > > I believe one atmosphere is still 100 kPa, the 1013,25 comes from the > International Standard Atmosphere. > > Commonly referred to as the ISA it's what manufacturers use to calibrate > instruments and what aircraft makers use to calibrate the performance of > aircraft. In the aviation world we constantly refer to the temperature being > below or above ISA, the lapse rate is fixed under ISA as 1.98 C up to 36090 > (11000 m) where it's supposed to be constant. Obviously in the real world it > changes which has an affect on performance. > > Mike Payne > > On 03/09/2011, at 13:57 , G. Stanley Doore wrote: > >> The 1013.25 mbar (101.325 kPa) pressure for altimeter settings is NOT >> "arbitrary" as Kilopascal & Wiki write. The standard altimeter setting for >> worldwide altimeter settings was determined from the mean surface pressure >> level. >> Stan Doore >> On Sep 3, 2011 11:36 AM, "Michael Payne" <[email protected]> wrote: >
