ASTM_D_3631_-_99_2017.pdf

Designation:D363199(Reapproved 2017)Standard Test Methods forMeasuring Surface Atmospheric Pressure1This standard is issued under the fixed designation D3631;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 These test methods cover the measurement of atmo-spheric pressure with two types of barometers:the Fortin-typemercurial barometer and the aneroid barometer.1.2 In the absence of abnormal perturbations,atmosphericpressure measured by these test methods at a point is valideverywhere within a horizontal distance of 100 m and a verticaldistance of 0.5 m of the point.1.3 Atmospheric pressure decreases with increasing heightand varies with horizontal distance by 1 Pa/100 m or lessexcept in the event of catastrophic phenomena(for example,tornadoes).Therefore,extension of a known barometric pres-sure to another site beyond the spatial limits stated in 1.2 canbe accomplished by correction for height difference if thefollowing criteria are met:1.3.1 The new site is within 2000 m laterally and 500 mvertically.1.3.2 The change of pressure during the previous 10 min hasbeen less than 20 Pa.The pressure,P2at Site 2 is a function of the known pressureP1at Site 1,the algebraic difference in height above sea level,h1 h2,and the average absolute temperature in the spacebetween.The functional relationship between P1and P2isshown in 10.2.The difference between P1and P2for each 1 mof difference between h1and h2is given in Table 1 and 10.4 forselected values of P1and average temperature.1.4 Atmospheric pressure varies with time.These test meth-ods provide instantaneous values only.1.5 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.Specific safetyprecautionary statements are given in Section 7.2.Referenced Documents2.1 ASTM Standards:2D1356 Terminology Relating to Sampling and Analysis ofAtmospheresD3249 Practice for General Ambient Air Analyzer Proce-duresIEEE/ASTM SI 10 Standard for Use of the InternationalSystem of Units(SI):The Modern Metric System3.Terminology3.1 Pressure for meteorological use has been expressed in anumber of unit systems including inches of mercury,millime-tres of mercury,millibars,and others less popular.These testmethods will use only the International System of Units(SI),asdescribed in IEEE/ASTM SI 10.3.1.1 Much of the apparatus in use and being sold reads inother than SI units,so for the convenience of the user thefollowing conversion factors and error equivalents are given.3.1.1.1 The standard for pressure(force per unit area)is thepascal(Pa).3.1.1.2 One standard atmosphere at standard gravity(9.80665 m/s2)is a pressure equivalent to:29.9213 in.Hg at 273.15 K760.000 mm Hg at 273.15 K1013.25 millibars14.6959 lbf/in.2101325 Pa or 101.325 kPa3.1.1.3 1 Pa is equivalent to:0.000295300 in.Hg at 273.15 K0.00750062 mm Hg at 273.15 K0.01000000 millibars0.000145037 lbf/in.20.000009869 standard atmospheres3.2 standard gravityas adopted by the International Com-mittee on Weights and Measures,an acceleration of 9.80665m/s2(see 10.1.3).3.3 The definitions of all other terms used in these testmethods can be found in Terminology D1356 and PracticeD3249.1These test methods are under the jurisdiction of ASTM Committee D22 on AirQuality and are the direct responsibility of Subcommittee D22.11 on Meteorology.Current edition approved March 1,2017.Published March 2017.Originallyapproved in 1977.Last previous edition approved in 2011 as D3631 99(2017).DOI:10.1520/D3631-99R17.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 4.Summary of Test Methods4.1 The instantaneous atmospheric pressure is measuredwith two types of barometers.4.2 Test Method A utilizes a Fortin mercurial barometer.The mercury barometer has the advantage of being fundamen-tal in concept and direct in response.The disadvantages of themercury barometer are the