1、Designation: D3631 99 (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 revi
2、sion. 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 barome
3、ter 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
4、 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 thefollo
5、wing 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,
6、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
7、 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 i
8、s 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
9、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
10、 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 t
11、he 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 m
12、illibars14.6959 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 a
13、cceleration 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 M
14、eteorology.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
15、.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 int
16、ernationally 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.14. Summary of Test Methods4.1 The instantaneou
17、s 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 more laborious reading procedureth
18、an the aneroid barometer, and the need for temperaturecorrection.4.3 Test Method B utilizes an aneroid barometer. Theaneroid barometer has the advantages of simplicity of reading,absence of mercury, no need for temperature compensation bythe observer, and easy detection of trend of change. The maind
19、isadvantages of the aneroid barometer are that it is notfundamental in concept as the mercury barometer, and itrequires calibration periodically against a mercury barometer.5. Significance and Use5.1 Atmospheric pressure is one of the basic variables usedby meteorologists to describe the state of th
20、e atmosphere.5.2 The measurement of atmospheric pressure is neededwhen differences from “standard” pressure conditions must beaccounted for in some scientific and engineering applicationsinvolving pressure dependent variables.5.3 These test methods provide a means of measuringatmospheric pressure wi
21、th the accuracy and precision compa-rable to the accuracy and precision of measurements made bygovernmental meteorological agencies.6. Apparatus6.1 Fortin Barometer, which is a mercurial barometer con-sisting of a glass tube containing mercury with an adjustablecistern and an index pointer projectin
22、g downward from the roofof the cistern. The mercury level may be raised or lowered byturning an adjustment screw beneath the cistern.6.1.1 To provide acceptable measurements, the specifica-tions of 6.1.2 6.1.11 must be met.6.1.2 Maximum error at 100 000 Pa 6 30 Pa.6.1.2.1 Maximum error at any other
23、pressure for a barom-eter whose range: (a) does not extend below 80 000 Pa 6 50Pa (b) extends below 80 000 Pa 6 80 Pa.6.1.2.2 For a marine application the error at a point must notexceed 650 Pa.6.1.3 Difference between errors over an interval of 10 000Pa or less 630 Pa.6.1.4 Accuracy must not deteri
24、orate by more than 650 Paover a period of a year.6.1.5 It must be transportable without loss of accuracy.6.1.6 A mercurial barometer must be able to operate atambient temperatures ranging from 253 to 333 K (20 to 60C)and must not be exposed to temperatures below 253 K(38C). It must be able to operat
25、e over ambient relativehumidities ranging from 0 to 100 %.6.1.7 A thermometer with a resolution of 0.11 K and aprecision and accuracy of 0.05 K must be attached to the barrelof the barometer.6.1.8 The actual temperature for which the scale of amercury barometer is designed to give true readings (ats
26、tandard gravity) must be engraved on the barometer.6.1.9 If the evacuated volume above the mercury columncan be pumped, the head vacuum must be measured with agauge such as a McLeod gauge or a thermocouple gauge andreduced to 10 Pa or less.6.1.10 The meniscus of a mercurial barometer must not beflat
27、.6.1.11 The axis of the tube must be vertical (that is, alignedwith the local gravity vector).6.2 Precision aneroid barometer, consisting of an evacuatedelastic capsule coupled through mechanical, electrical, oroptical linkage to an indicator.6.2.1 To provide acceptable measurements, an aneroid ba-r
28、ometer must meet the specifications of 6.2.2 6.2.7.6.2.2 Resolution of 50 Pa or less.6.2.3 Precision of 650 Pa.6.2.4 Accuracy of 650 Pa root mean square error with amaximum observed error not to exceed 150 Pa throughout thecalibration against a basic standard.6.2.5 Temperature compensation must be i
29、ncluded to pre-vent a change in reading of more than 50 Pa for a change oftemperature of 30 K.6.2.6 The accuracy must not deteriorate by more than 6100Pa over a period of a year.6.2.7 The hysteresis must be sufficiently small to ensure thatthe difference in reading before a 5000-Pa pressure change a
30、ndafter return to the original value does not exceed 50 Pa.6.3 Static Pressure HeadAtmospheric pressure-measuringinstruments may be installed inside an enclosed space. Thepressure in the space must, however, be directly coupled to thepressure of the free atmosphere and not artificially affected byhe
31、ating, ventilating, or air-conditioning equipment, or by thedynamic effects of wind passage.6.3.1 The Manual of Barometry (1)3describes these effects.For barometers with a static port they can be overcome with astatic pressure vent, such as that described by Gill (2), mountedoutside and beyond the i
32、nfluence of the building. It is practicalto consider an external static vent installation if and only if thepressure in the building differs by more than 30 Pa from truepressure. The pressure difference due to a ventilating or air3Boldface numbers in parentheses refer to references at the end of the
33、se testmethods.TABLE 1 Selected ValuesAverageTempera-ture,T11T22Pressure P1,Pa110 000 100 000 90 000 80 000 70 000Correction to P1, Pa/m, positive if h1 h, negative if h1 h2230 16 15 13 12 10240 16 14 13 11 10250 15 14 12 11 10260 14 13 12 11 9270 14 13 11 10 9280 13 12 11 10 9290 13 12 11 9 8300 13
34、 11 10 9 8310 12 11 10 9 8D3631 99 (2017)2conditioning system, or both can be determined from pressurereadings taken with a precision aneroid barometer inside andoutside the building on calm days when the ventilating and airconditioning system is in operation. The existence of pressureerrors due to
35、the dynamic effects of wind on the building canoften be diagnosed by careful observation of a fast responsebarometer in the building during periods of gusty winds.6.3.2 The significant pressure field near a building in windcan extend to a height of 2.5 times the height of the buildingand to a horizo
36、ntal distance up to 10 times the height of thebuilding to the leeward. It may be impractical to locate a staticvent beyond this field but the following considerations must bemade:6.3.2.1 The static vent must not be located on a side of thebuilding;6.3.2.2 The distance from the building must be as la
37、rge aspractical;6.3.2.3 The length of the tube connecting the vent to thebarometer must be minimized;6.3.2.4 To avoid blockages, a vertical run of connecting tubeis preferable to a horizontal run; and6.3.2.5 The connecting tube system must include moisturetraps and drainage slopes on horizontal runs
38、.6.3.3 The tubing used to connect the vent to the barometerhas a minimum allowable internal diameter that is a function ofthe ambient static pressure, the volume of the air chambersassociated with the instrument making the pressuremeasurement, the length of the tube between the static headand the ba
39、rometer, the viscosity of the air in the tubing andconnected equipment. The time lag constant must not exceed 1s so that for pressure and temperature of the zero pressurealtitude in the standard atmosphere, the inside diameter d of thetubing connecting the static pressure head with the barometermust
40、 be such thatd.7.21 310m29LV!(1)where:L = length of the tube, m,V = volume of the air capacity of the pressure responsiveinstrument and any connected air chambers within thesystem together with one half the volume of the tubing,m3, andd = inside diameter of the tubing, m.When this calculation is mad
41、e the minimum allowable insidediameter will frequently be 5 mm or less. It is often moreconvenient to use tubing larger than this size, and use of suchlarger tubing enhances the value of the static head and makesit applicable to a wider range of temperatures and pressures.7. Safety Precautions7.1 Wa
42、rningMercury is a hazardous substance that cancause illness and death. Inhalation of mercury vapor is a healthhazard, even in small quantities. Prolonged exposure canproduce serious mental and physical impairment. Mercury canalso be absorbed through the skin, so avoid direct contact. Theeffects are
43、cumulative.7.2 Store mercury in closed, shatter-proof non-metalliccontainers to control its evaporation.7.3 Do not store or attempt to operate a mercurial barometerat temperatures below 235 K (38C), the freezing point ofmercury.7.4 Work with mercury only in well-ventilated spaces,preferably under a
44、fume hood or similar device. Use non-permeable rubber gloves at all times and wash hands immedi-ately after any operation involving mercury. Exercise extremecare to avoid spilling mercury. Minimize the effect of spills byworking above a large shallow pan.7.5 Mercurial barometers should be installed
45、only wherethere is adequate ventilation. The floor beneath a mercurialbarometer should be impermeable.7.6 In a mercurial barometer, a broken tube, cistern, or bagwill release mercury. Immediately clean up any spills usingprocedures recommended explicitly for mercury. Carefullycollect, place, and sea
46、l all spilled mercury in an appropriatecontainer. Do not re-use; dispose of spilled mercury andmercury contaminated materials in a safe, environmentallyacceptable manner.8. Calibration and Standardization8.1 A barometer is calibrated by comparing it with asecondary standard traceable to one of the p
47、rimary standards atlocations listed in Table 2.8.2 For the United States, this standard is maintained by theNational Institute of Standards and Technology.48.3 Except in the case of catastrophic phenomena (forexample, tornadoes) the horizontal pressure gradient at theearths surface is less than 1 Pa
48、/100 m so that the pressure attwo instruments within 100 m of each other horizontally willnot differ by an amount large enough to measure with instru-ments suggested for this test method. Instruments separated by4Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., St
49、op 1070, Gaithersburg, MD 20899-1070, http:/www.nist.gov.TABLE 2 Regional Standard BarometersRegion Location CategoryI Pretoria, South Africa ArII Calcutta, India BrIII Rio de Janeiro, Brazil ArBuenos Aires, Argentina BrMaracay, Venezuela BrIV Washington, DC, Ar(Gaithersburg, Md.), USAV Melbourne, Australia ArVI London, United Kingdom ArLeningrad, U.S.S.R. ArParis, France ArHamburg, Federal Republic ofGermanyArArA barometer that has been selected by regional agreement as a referencestandard for barometers of that region and is capable of independent determina-tion
