1、Designation: D 3631 99 (Reapproved 2004)Standard Test Methods forMeasuring Surface Atmospheric Pressure1This standard is issued under the fixed designation D 3631; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last re
2、vision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 These methods cover the measurement of atmosphericpressure with two types of barometers: the Fortin-type mercu-rial baromete
3、r and the aneroid barometer.1.2 In the absence of abnormal perturbations, atmosphericpressure measured by these 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
4、 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 cr
5、iteria 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
6、 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 t
7、ime. These methodsprovide instantaneous values only.1.5 The values stated in SI units are to be regarded as thestandard.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-pr
8、iate 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:2D 1356 Terminology Relating to Sampling and Analysis ofAtmospheresD 3249 Practice for Ge
9、neral 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, an
10、d others less popular. Thesemethods 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
11、.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 equivalen
12、t 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).1These test methods are under the
13、jurisdiction of ASTM Committee D22 onSampling and Analysis of Atmospheres and are the direct responsibility ofSubcommittee D22.11 on Meteorology.Current edition approved April 1, 2004. Published June 2004. Originallyapproved in 1977. Last previous edition approved in 1999 as D 3631 - 99.2For referen
14、ced 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West C
15、onshohocken, PA 19428-2959, United States.3.3 The definitions of all other terms used in these methodscan be found in Terminology D 1356 and Practice D 3249.4. Summary of Methods4.1 The instantaneous atmospheric pressure is measuredwith two types of barometers.4.2 Method A utilizes a Fortin mercuria
16、l barometer. Themercury barometer has the advantage of being fundamental inconcept and direct in response. The disadvantages of themercury barometer are the more laborious reading procedurethan the aneroid barometer, and the need for temperaturecorrection.4.3 Method B utilizes an aneroid barometer.
17、The aneroidbarometer has the advantages of simplicity of reading, absenceof mercury, no need for temperature compensation by theobserver, and easy detection of trend of change. The maindisadvantages of the aneroid barometer are that it is notfundamental in concept as the mercury barometer, and itreq
18、uires 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 the atmosphere.5.2 The measurement of atmospheric pressure is neededwhen differences from “standard” pressure condit
19、ions must beaccounted for in some scientific and engineering applicationsinvolving pressure dependent variables.5.3 These methods provide a means of measuring atmo-spheric pressure with the accuracy and precision comparable tothe accuracy and precision of measurements made by govern-mental meteorolo
20、gical 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 projecting downward from the roofof the cistern. The mercury level may be raised or lowered byturning an adjustment screw bene
21、ath 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 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
22、.6.1.2.2 For a marine application the error at a point must notexceed 6 50 Pa.6.1.3 Difference between errors over an interval of 10 000Pa or less 6 30 Pa.6.1.4 Accuracy must not deteriorate by more than 6 50 Paover a period of a year.6.1.5 It must be transportable without loss of accuracy.6.1.6 A m
23、ercurial 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 operate over ambient relativehumidities ranging from 0 to 100 %.6.1.7 A thermometer with a resolution of 0.11 K and apre
24、cision 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 (atstandard gravity) must be engraved on the barometer.6.1.9 If the evacuated volume above the mercury columncan be pu
25、mped, the head vacuum must be measured with agage such as a McLeod gage or a thermocouple gage andreduced to 10 Pa or less.6.1.10 The meniscus of a mercurial barometer must not beflat.6.1.11 The axis of the tube must be vertical (that is, alignedwith the local gravity vector).6.2 Precision aneroid b
26、arometer, consisting of an evacuatedelastic capsule coupled through mechanical, electrical, oroptical linkage to an indicator.6.2.1 To provide acceptable measurements, an aneroid ba-rometer 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 6 50 Pa.6.2.4
27、 Accuracy of 6 50 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 included to pre-vent a change in reading of more than 50 Pa for a change oftemperature of 30 K.6.2.6 The accuracy mu
28、st not deteriorate by more than 6 100Pa 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 andafter return to the original value does not exceed 50 Pa.6.3 Static Pressure HeadAtmospheric pressure-measuring
29、instruments may be installed inside an enclosedspace. The pressure in the space must, however, be directlycoupled to the pressure of the free atmosphere and notartificially affected by heating, ventilating, or air-conditioningequipment, or by the dynamic effects of wind passage.6.3.1 The Manual of B
30、arometry (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 influence of the building. It is practicalto consider an external static vent installation if and only if the3Bold
31、face numbers in parentheses refer to references at the end of thesemethods.TABLE 1 Selected ValuesAverageTempera-ture,T11 T22Pressure 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
32、 11 9270 14 13 11 10 9280 13 12 11 10 9290 13 12 11 9 8300 13 11 10 9 8310 12 11 10 9 8D 3631 99 (2004)2pressure in the building differs by more than 30 Pa from truepressure. The pressure difference due to a ventilating or airconditioning system, or both can be determined from pressurereadings taken
33、 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 the dynamic effects of wind on the building canoften be diagnosed by careful observation of a fast responsebarometer
34、 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 horizontal distance up to 10 times the height of thebuilding to the leeward. It may be impractical to locate a staticvent
35、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 large aspractical;6.3.2.3 The length of the tube connecting the vent to thebarometer must be minimized;6.3.2.4 To avoi
36、d 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.6.3.3 The tubing used to connect the vent to the barometerhas a minimum allowable internal diameter that is a funct
37、ion ofthe ambient static pressure, the volume of the air chambersassociated with the instrument making the pressure measure-ment, the length of the tube between the static head and thebarometer, the viscosity of the air in the tubing and connectedequipment. The time lag constant must not exceed1ssot
38、hatfor pressure and temperature of the zero pressure altitude in thestandard atmosphere, the inside diameter d of the tubingconnecting the static pressure head with the barometer must besuch thatd . 7.21 3 10m29LV!(1)where:L = length of the tube, m,V = volume of the air capacity of the pressure resp
39、onsiveinstrument and any connected air chambers within thesystem together with one half the volume of thetubing, m3, andd = inside diameter of the tubing, m.When this calculation is made the minimum allowable insidediameter will frequently be 5 mm or less. It is often moreconvenient to use tubing la
40、rger 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 Warning: Mercury is a hazardous substance that cancause illness and death. Inhalation of mercury vapor is a healthhaz
41、ard, 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 cumulative.7.2 Store mercury in closed, shatter-proof non-metalliccontainers to control its evaporation.7.3 Do no
42、t 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 fume hood or similar device. Use non-permeable rubber gloves at all times and wash hands immedi-ately after any
43、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 only wherethere is adequate ventilation. The floor beneath a mercurialbarometer should be impermeable.7.6 In a m
44、ercurial barometer, a broken tube, cistern, or bagwill release mercury. Immediately clean up any spills usingprocedures recommended explicitly for mercury. Carefullycollect, place, and seal all spilled mercury in an appropriatecontainer. Do not re-use; dispose of spilled mercury andmercury contamina
45、ted 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 primary standards atlocations listed in Table 2.8.2 For the United States this standard is maintained by theNatio
46、nal Institute of Standards and Technology, Gaithersburg,MD 20899.8.3 Except in the case of catastrophic phenomena (forexample, tornadoes) the horizontal pressure gradient at theearths surface is less than 1 Pa/100 m so that the pressure attwo instruments within 100 m of each other horizontally willn
47、ot differ by an amount large enough to measure with instru-ments suggested for this method. Instruments separated by avertical distance of less than 0.5 m may be compared withoutcorrecting for height difference.TABLE 2 Regional Standard BarometersRegion Location CategoryI Pretoria, South Africa ArII
48、 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 sele
49、cted by regional agreement as a referencestandard for barometers of that region and is capable of independent determina-tion of pressure to an accuracy of 65 Pa.BrA working standard barometer with known errors established by comparisonwith a primary or secondary standard. Such barometers are used in a region wherethe National meteorological services of the region agree to use them as thestandard barometer for the region in the event that a barometer of category Arisunavailable.Taken from Annex 3, of Guide to Meteorological Instruments and ObservingPractice, World Meteorolo
