1、Designation: D 6326 08Standard Practice forThe Selection of Maximum Transit-Rate Ratios and Depthsfor the U.S. Series of Isokinetic Suspended-SedimentSamplers1This standard is issued under the fixed designation D 6326; the number immediately following the designation indicates the year oforiginal ad
2、option or, in the case of revision, the year of last revision. 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 This practice covers the maximum transit-rate ratios anddepths for se
3、lected suspended-sediment sampler-nozzle-container configurations.1.2 This practice explains the reasons for limiting thetransit-rate ratio and depths that suspended-sediment samplerscan be correctly used.1.3 This practice give maximum transit-rate ratios anddepths for selected isokinetic suspended-
4、sediment sampler/nozzle/container size for samplers developed by the FederalInteragency Sedimentation Project.1.4 Throughout this practice, a samplers lowering rate isassumed to be equal to its raising rate.1.5 The values stated in inch-pound units are to be regardedas the standard. The SI units giv
5、en in parentheses are forinformation only.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 regulator
6、y limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1129 Terminology Relating to WaterD 4410 Terminology for Fluvial SedimentD 4411 Guide for Sampling Fluvial Sediment in Motion3. Terminology3.1 Definitions:3.1.1 For Definitions of terms used in this practice, refer toTerminology
7、 D 1129 and Terminology D 4410.3.2 Definitions of Terms Specific to This Standard:3.2.1 approach anglethe angle between the velocity vec-tor of the approaching flow and the centerline of the nozzle.3.2.2 approaching flowflow immediately upstream of anozzles entrance.3.2.3 bag samplera suspended-sedi
8、ment sampler thatuses a flexible collapsible bag as a sample container.3.2.4 compression ratethe rate at which the air is com-pressed in the sample container and is a function of the speedat which the sampler is lowered in the sampling vertical.3.2.5 isokineticthe conditions under which the directio
9、nand speed of the flowing water/sediment mixture are un-changed upon entering the nozzle of a suspended-sedimentsampler.3.2.6 maximum transit ratethe maximum speed at whichthe sampler can be lowered and raised in the sampling verticaland still have the sample collected isokinetically.3.2.7 transit r
10、atethe speed at which the suspended sedi-ment sampler is lowered and raised in the sampling vertical.3.2.8 transit-rate ratiothe ratio computed by dividing thetransit rate by the mean stream velocity in the vertical beingsampled.4. Summary of Practice4.1 This practice describes the maximum transit-r
11、ate ratiosand depths that can be used for selected isokinetic suspended-sediment sampler/nozzle/container configurations to ensureisokinetic sampling. (Manufacturing differences in the produc-tion of sediment samplers may result in some samplers notcollecting a sample isokinetically. It is the users
12、 responsibilityto ensure through calibration that the sampler does collect asample isokinetically. Guide D 4411 describes a process forchecking calibration of suspended-sediment samplers.)5. Significance and Use5.1 This practice describes the maximum transit-rate ratiosand depths that can be used fo
13、r selected isokinetic suspended-sediment sampler/nozzle/container configurations in order toinsure isokinetic sampling.5.2 This practice is designed to be used by field personnelcollecting whole-water samples from open channel flow.1This practice is under the jurisdiction of ASTM Committee D19 on Wa
14、ter andthe direct responsibility of Subcommittee D19.07 on Sediments, Geomorphology,and Open-Channel Flow.Current edition approved May 1, 2008. Published May 2008. Originallyapproved in 1998. Last previous edition approved in 2003 as D 6326 03.2For referenced ASTM standards, visit the ASTM website,
15、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 Conshohocken, PA 19428-2959, United States.6.
16、 Background6.1 The distribution of velocity and sediment concentrationin a sampling vertical is very complex. The velocity of the flowwill generally decrease with depth while the suspended-sediment concentration will normally increase with depth in avertical. For a sediment sampler to collect a repr
17、esentativevolume, the water-sediment mixture must enter the nozzlewithout undergoing a change in direction or speed. Ideally, thewater must enter the nozzle at the same velocity as theapproaching flow. When the velocity is unchanged uponentering the nozzle, the condition is termed isokinetic. Depth-
18、and point-integrating samplers sample isokinetically only iftheir nozzles point directly into the flow and the samplers areused within certain ranges of depths. Depth-integrating sam-plers also operate isokinetically only when their vertical transitrate is within a given range.6.2 If the velocity of
19、 the water-sediment mixture enteringthe nozzle exceeds that of the approach velocity, the samplesediment concentration is smaller than the concentration of theapproaching flow. Decreasing the velocity in the nozzle com-pared to the approach velocity will cause the sample sedimentconcentration to be
20、greater than that of the approaching flow.The magnitude of the difference between nozzle and approachvelocity is related to the degree of increase or decrease inconcentration. The concentration shift is also related to thesizes of the grains in suspension. The larger the grain size, thelarger the po
21、tential shift in concentrations will be.6.3 The sampler will not operate properly if the transit rateis too fast, the sampling depth is too great, or both. See GuideD 4411 for more details on proper use of depth integratingsuspended sediment samplers.6.4 Two factors control the maximum transit rate
22、for asampler: approach angle and the compression rate.6.4.1 At a given sample vertical, as the transit rate increases,the approach angle increases. If the transit-rate exceeds 0.4times the mean flow velocity in the vertical, the intake velocityundergoes a significant acceleration due to changes in f
23、lowdirection. The maximum vertical transit rate for a depth-integrating sampler or point-integrating sampler used for depthintegrating, should not exceed 0.4 times the mean streamvelocity of the section.6.4.2 The compression rate, which is related to the compres-sion limit, may restrict the vertical
24、 transit rate to less than 0.4times the mean stream velocity when a rigid sample containeris used. As the sampler is lowered through the water, theincreasing water pressure compresses the air in the samplercontainer. If the sampler is lowered slowly, the volume of theincoming water exceeds the volum
25、e lost, the displaced air exitsthrough the samplers exhaust vent. If the sampler is loweredrapidly, the volume of the incoming water is less than thevolume lost to compression. Pressure inside the samplercontainer is less than the hydrostatic pressure outside thesampler. The self regulating properti
26、es of the sampler losecontrol. The intake velocity increases above the stream veloc-ity. In severe cases, water enters the sampler through theair-exhaust vent. If the sampler is raised too rapidly, the airinside the bottle expands and, if not relieved by venting, willnot escape fast enough through t
27、he air-exhaust vent. Thepressure unbalance causes the intake velocity to be less thanthe approach velocity. The compression-rate limit is a functionof the diameter of the nozzle, volume of the sample container,and altitude. For large bottles with small nozzles it can limit thevertical transit rate t
28、o less than 3 % of the mean streamvelocity. Table 1 lists the maximum transit-rates ratios forcommonly used combinations of sampler nozzle and containersizes.TABLE 1 Maximum Transit-Rate Ratios and Depths for Sampler/Container/Nozzle ConfigurationsSamplerUSNozzleSize, In. (mm)NozzleColorContainerSiz
29、eMaximumDepth, ft (m)Max ratioRt/VmADH-4814 (6.35) Yellow Pint 9 (2.74) 0.4DH-48316 (4.76) Yellow Pint 15 (4.57) 0.4DH-75P316 (4.76) White Pint 15 (4.57) 0.4DH-75Q316 (4.76) White Quart 15 (4.57) 0.2DH-75H316 (4.76) White 2 L 15 (4.57) 0.1DH-5918 (3.17) Red Pint 15 (4.57) 0.2DH-59316 (4.76) Red Pint
30、 15 (4.57) 0.4DH-5914 (6.35) Red Pint 9 (2.74) 0.4DH-7618 (3.17) Red Quart 15 (4.57) 0.1DH-76316 (4.76) Red Quart 15 (4.57) 0.2DH-7614 (6.35) Red Quart 15 (4.57) 0.4DH-8118 (3.17) White Pint 15 (4.57) 0.2DH-81316 (4.76) White Pint 15 (4.57) 0.4DH-8114 (6.35) White Pint 9 (2.74) 0.4DH-81516 (7.93) Wh
31、ite Pint 6 (1.83) 0.4DH-8118 (3.17) White Quart 15 (4.57) 0.1DH-81316 (4.76) White Quart 15 (4.57) 0.2DH-8114 (6.35) White Quart 15 (4.57) 0.4DH-81516 (7.93) White Quart 10 (3.05) 0.4D-49/D-7418 (3.17) Green Pint 15 (4.57) 0.2D-49/D-74316 (4.76) Green Pint 15 (4.57) 0.4D-49/D-7414 (6.35) Green Pint
32、9 (2.74) 0.4D-7418 (3.17) Green Quart 15 (4.57) 0.1D-74316 (4.76) Green Quart 15 (4.57) 0.2D-7414 (6.35) Green Quart 15 (4.57) 0.4DH-95316 (4.76) White 1 L 15 (4.57) 0.2DH-9514 (6.35) White 1 L 15 (4.57) 0.3DH-95516 (7.93) White 1 L 13 (3.96) 0.4D-95316 (4.76) White 1 L 15 (4.57) 0.2D-9514 (6.35) Wh
33、ite 1 L 15 (4.57) 0.3D-95516 (7.93) White 1 L 13 (3.96) 0.4D-96/D-96Al316 (4.76) White 3L - bag 110 (33.4) 0.4D-96/D-96Al14 (6.35) White 3L - bag 60 (18.3) 0.4D-96/D-96Al516 (7.93) White 3L - bag 39 (11.9) 0.4D-99316 (4.76) White 3L - bag 110 (33.4) 0.4D-9914 (6.35) White 3L - bag 60 (18.3) 0.4D-995
34、16 (7.93) White 3L - bag 39 (11.9) 0.4D-99316 (4.76) White 6L - bag 220 (67.0) 0.4D-9914 (6.35) White 6L - bag 120 (36.6) 0.4D-99516 (7.93) White 6L - bag 78 (23.8) 0.4DH-2316 (4.76) White 1 L - bag 35 (11.0) 0.4DH-214 (6.35) White 1 L - bag 20 (6.09) 0.4DH-2516 (7.93) White 1 L - bag 13 (3.96) 0.4A
35、Rt = transit rate; Vm = mean stream velocity in the vertical being sampled.D63260826.4.3 Because no air is contained inside of the bag, thecompression rate limit does not apply to bag samplers.6.5 Edwards and Glysson3discuss the proper use of thesamplers and transit-rate ratios for some of the more
36、commoncombinations used by the US Geological Survey (USGS).Because of difficulties in maintaining a slow transit rate, theUSGS does not recommend using the USD-77 sampler.6.6 Based on compression, isokinetic inflow rates, andlimits on sample volumes to prevent overfilling4, the maximumdepth that any
37、 rigid container can be lowered to is about 15 ft(4.572 m) (FISP).5If the sampler is lowered below themaximum depth limit, the bottle overfills.As shown in Table 1,the maximum depth depend on sampler, nozzle, and containersize. Depending on the maximum percentage of useful volume,depth limit also va
38、ries with sample container size and volumeof the pressure compensating chamber for point-integratingsamplers. The values given in Table 1 are for sea levelconditions. The maximum depth decreases about 1 ft (0.3048m) for every 1000-ft (304.8 m) increase in elevation.6.6.1 The maximum depth that a bag
39、 sampler may collect asample isokineticly is limited by the nozzle and bag size. SeeTable 1.6.7 For additional information about isokinetic suspended-sediment samplers, see Footnote 8.67. Procedure7.1 Table 1 lists the most commonly use suspended-sediment samplers in he United States. A “D” in the n
40、ameindicates that it is a depth-integrating sampler, a “P” indicatesthat it is a point-integrating sampler.7.2 To determine the maximum depth for a sampler, find thenozzle size and container size and then read across to themaximum depth.7.3 To determine the maximum transit-rate, find thesampler/nozz
41、le/container to be used and read across to themaximum ratio (Rt/Vm). Then multiply this ratio by the meanstream velocity in the vertical to be sampled.7.3.1 The maximum transit rate determined in 7.3 should beused as a practice, the actual transit rate can be and in mostcases should be less than the
42、 maximum rate computed.8. Precision8.1 The transit-rate ratios given in this practice and deter-mined graphically and rounded to one significant figure.8.2 The precision of the collected sample is a function of theconditions encountered and the measurement techniques usedfor each measurement.9. Keyw
43、ords9.1 sampling; sediment; surface-water; isokinetic samplingASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such
44、patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited
45、either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fa
46、ir hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this st
47、andard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).3Edwards, T.K., and Glysson, G.D., “Field Methods for Measurement of FluvialSediment,” U.S. Geological Survey, Techniqu
48、es of Water Resource Investigations,Book 3, Chapter C2, 1998.4Maximum sample volume to prevent over filling is assumed to be approxi-mately23 the sample container volume.5FISP, Federal Interagency Sediment Project Report No. 6, 1952, The Design ofImproved Types of Suspended-Sediment Samplers.6Contact the Project Chief, Federal Interagency Sedimentation Project, Water-ways Experiment Station, 3909 Halls Ferry Road, Vicksburg, MS 39180-6199.D6326083
