1、Designation: D 6326 98 (Reapproved 2003)Standard 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
2、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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the maximum transit-rate ratio
3、s anddepths for selected 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 iso
4、kinetic suspended-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
5、. The SI units given 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-b
6、ility of regulatory 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, r
7、efer toTerminology D 1129 and Terminology D 44103.2 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 compressio
8、n 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.3.2.4 isokineticthe conditions under which the directionand speed of the flowing water/sediment mixture are un-changed upon entering the nozzl
9、e of a suspended-sedimentsampler.3.2.5 maximum transit ratethe maximum speed at whichthe sampler can be lowered and raised in the sampling verticaland still have the sample collected isokinetically.3.2.6 transit ratethe speed at which the suspended sedi-ment sampler is lowered and raised in the samp
10、ling vertical.3.2.7 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-rate ratiosand depths that can be used for selected isokinetic suspended-sediment sample
11、r/nozzle/container configurations to insureisokinetic sampling. (Manufacturing differences in the produc-tion of sediment samplers may result in some samplers notcollecting a sample isokinetically. It is the users responsibilityto insure through calibration that the sampler does collect asample isok
12、inetically. 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 for selected isokinetic suspended-sediment sampler/nozzle/container configurations in ord
13、er toinsure isokinetic sampling.1This practice is under the jurisdiction of ASTM Committee D19 on Water andthe direct responsibility of Subcommittee D19.07 on Sediment, Geomorphology,and Open Channel Flow.Current edition approved June 10, 2003. Published August 2003. Originallyapproved in 1998. Last
14、 previous edition approved in 1998 as D 6326 98.2For 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.1Copyright AS
15、TM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 This practice is designed to be used by field personnelcollecting whole-water samples from open channel flow.6. Background6.1 The distribution of velocity and sediment concentrationin a sampling
16、 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 representativevolume, the water-sediment mixture must enter the nozzlewithout undergoin
17、g 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-and point-integrating samplers with rigid sample containerssample isokinetically on
18、ly if their nozzles point directly intothe flow and the samplers are used within certain ranges ofdepths. Depth-integrating samplers also operate isokineticallyonly when their vertical transit rate is within a given range.6.2 If the velocity of the water-sediment mixture enteringthe nozzle exceeds t
19、hat 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 greater than that of the approaching flow.The magnitude
20、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 potential shift in concentrations will be.6.3 The sampler
21、will not operate properly if the transit rateis too fast and/or sampling depth is too great. See GuideD 4411 for more details on proper use of depth integratingsuspended sediment samplers.6.4 Two factors control the maximum transit rate for asampler: approach angle and the compression rate.6.4.1 At
22、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 flowdirection. The maximum vertical transit rate for a depth-int
23、egrating 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 transit rate to less than 0.4times the mean stream velocity. A
24、s the sampler is loweredthrough the water, the increasing water pressure compressesthe air in the sampler container. If the sampler is loweredslowly, the volume of the incoming water exceeds the volumelost, the displaced air exits through the samplers exhaust vent.If the sampler is lowered rapidly,
25、the volume of the incomingwater is less than the volume lost to compression. Pressureinside the sampler container is less than the hydrostaticpressure outside the sampler. The self regulating properties ofthe sampler loose control. The intake velocity increases abovethe stream velocity. In severe ca
26、ses, water enters the samplerthrough the air-exhaust vent. If the sampler is raised toorapidly, the air inside the bottle expands and, if not relieved byventing, will not escape fast enough through the air-exhaustvent. The pressure unbalance causes the intake velocity to beless than the approach vel
27、ocity. The compression-rate limit is afunction of the diameter of the nozzle, volume of the samplecontainer, and altitude. For large bottles with small nozzles itcan limit the vertical transit rate to less than 3 % of the meanstream velocity. Table 1 lists the maximum transit-rates ratiosfor commonl
28、y used combinations of sampler nozzle andcontainer sizes.6.5 Edwards and Glysson3discuss the proper use of thesamplers and transit-rate ratios for some of the more commoncombinations used by the US Geological Survey (USGS).Because of difficulties in maintaining a slow transit rate, the3Edwards, T.K.
29、, and Glysson, G.D., “Field Methods for Measurement of FluvialSediment,” U.S. Geological Survey, Techniques of Water Resource Investigations,Book 3, Chapter C2, 1998.TABLE 1 Maximum Transit-Rate Ratios and Depths for Sampler/Bottle/Nozzle ConfigurationsSamplerUSNozzleSize, In. (mm)NozzleColorContain
30、erSizeMaximumDepth, 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
31、 Pint 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 (7.9
32、3) White 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
33、Pint 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) 0.4D-7718 (3.17) White 3 L 15 (4.57) 0.03D-77316 (4.76) White 3 L 15 (4.57) 0.07D-7714 (6.35) White 3 L 15 (4.57) 0.1D-77516 (7.93) White 3 L 15 (4.57) 0.2P-61B 316 (4.
34、76) Blue Pint 180 (54.86) 0.4P-63B 316 (4.76) Blue Pint 180 (54.86) 0.4P-72B 316 (4.76) Blue Pint 72 (21.95) 0.4P-61B 316 (4.76) Blue Quart 120 (36.58) 0.2P-63B 316 (4.76) Blue Quart 120 (36.58) 0.2P-72B 316 (4.76) Blue Quart 51 (15.54) 0.2ARt = transit rate; Vm = mean stream velocity in the vertica
35、l being sampled.BTo sample the full depth, samples must be collected in increments of no morethen 30 ft (9.144 m). See Footnote 5 for more details.D 6326 98 (2003)2USGS Office of Surface Water does not recommend using the18 or316-in. (3.175 or 4.762 mm) nozzles with the USD-77sampler.6.6 Based on co
36、mpression, isokinetic inflow rates, andlimits on sample volumes to prevent overfilling4, the maximumdepth that any 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 depe
37、nd on sampler, nozzle, and containersize. Depending on the maximum percentage of useful volume,depth limit also varies 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 d
38、ecreases about 1 ft (0.3048m) for every 1000-ft (304.8 m) increase in elevation.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 nameindicates
39、 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/nozzle/container
40、 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 maximum rat
41、e 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. Keywords9.1 samp
42、ling; 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 patent right
43、s, 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 either for r
44、evision 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 fair hearing y
45、ou 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 standard may b
46、e 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).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.D 6326 98 (2003)3
