1、Designation:D340415Standard Guide forMeasuring Matric Potential in Vadose Zone UsingTensiometers1This standard is issued under the fixed designation D3404;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A nu
2、mber in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This guide covers the measurement of matric potentialin the vadose zone using tensiometers.The theoretical andpractical considerations pertai
3、ning to successful onsite use ofcommercial and fabricated tensiometers are described.Mea-surement theory and onsite objectives are used to developguidelines for tensiometer selection,installation,and opera-tion.1.2 UnitsThe values stated in SI units are to be regardedas the standard.1.3 This standar
4、d 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.The use of amercury manometer has
5、inherent safety concerns regarding thehandling of and potential exposure to mercury.Mercury metalvapor poisoning has long been recognized as a hazard.Whenusing equipment containing or requiring the use of mercury,take all precautions and care to avoid the escape of mercuryvapor or the spillage of me
6、rcury.Maximum limits for mercuryconcentrations in industrial atmospheres are set by govern-mental agencies.These limits are usually based upon recom-mendations made by the American Conference of Governmen-tal Industrial Hygienists*.It is possible for the concentrationof mercury vapors accompanying s
7、pills from brokenthermometers,barometers,and other instruments using mer-cury to exceed these limits.Mercury,being a heavy liquid withhigh surface tension,readily disperses into small droplets afterspills,lodging in cracks and crevices.Resultant increasedsurface area of the mercury due to this dispe
8、rsion promoteshigher mercury concentrations in the surrounding air.Mercuryvapor concentrations are readily measured using commerciallyavailable instrumentation.To monitor environmental hazards itis advisable to make periodic checks for mercury content atlocations where mercury is exposed to the atmo
9、sphere.Use aspill kit for clean-up whenever spillage occurs.After spills andclean-up,make thorough checks for mercury vapor concentra-tions in the atmosphere.*In 1993,this Conference hadheadquarters located in Building D-7 at 6500 Glenway Drive,Cincinnati,Ohio 45211.1.4 This guide offers an organize
10、d collection of informationor a series of options and does not recommend a specificcourse of action.This document cannot replace education orexperience and should be used in conjunction with professionaljudgment.Not all aspects of this guide may be applicable in allcircumstances.This ASTM standard i
11、s not intended to repre-sent or replace the standard of care by which the adequacy ofa given professional service must be judged,nor should thisdocument be applied without consideration of a projects manyunique aspects.The word“Standard”in the title of thisdocument means only that the document has b
12、een approvedthrough the ASTM consensus process.2.Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil,Rock,and ContainedFluids3.Terminology3.1 For definitions of common technical terms in thisstandard,refer to Terminology D653.3.2 Definitions of Terms Specific to This Standard:3
13、.2.1 accuracy of measurementthe difference between thevalue of the measurement and the true value.3.2.2 hysteresisthat part of inaccuracy attributable to thetendency of a measurement device to lag in its response toenvironmental changes;parameters affecting pressure-sensorhysteresis are temperature
14、and measured pressure.3.2.3 precision(repeatability)the variability among nu-merous measurements of the same quantity.1This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rockand is the direct responsibility of Subcommittee D18.21 on Groundwater andVadose Zone Investigations.Curren
15、t edition approved April 15,2015.Published May 2015.Originallyapproved in 1991.Last previous edition approved in 2013 as D3404 91(2013).DOI:10.1520/D3404-15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMSt
16、andards 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 States1 3.2.4 resolutionthe smallest division of the scale used fora measurement,and it is a factor in determining precision andaccuracy.4.Summary of Guide4.1 The measurement of matric potential in the vadose zonecan be accomplished using tensiometers that create a saturatedhydraulic link between the soil
