ASTM D6326-08(2014)

Standard Practice for The Selection of Maximum Transit-Rate Ratios and Depths for the U.S. Series of Isokinetic Suspended-Sediment Samplers

SIGNIFICANCE AND USE
5.1 This practice describes the maximum transit-rate ratios and depths that can be used for selected isokinetic suspended-sediment sampler/nozzle/container configurations in order to insure isokinetic sampling.  
5.2 This practice is designed to be used by field personnel collecting whole-water samples from open channel flow.
SCOPE
1.1 This practice covers the maximum transit-rate ratios and depths for selected suspended-sediment sampler-nozzle-container configurations.  
1.2 This practice explains the reasons for limiting the transit-rate ratio and depths that suspended-sediment samplers can be correctly used.  
1.3 This practice give maximum transit-rate ratios and depths for selected isokinetic suspended-sediment sampler/nozzle/container size for samplers developed by the Federal Interagency Sedimentation Project.  
1.4 Throughout this practice, a samplers lowering rate is assumed to be equal to its raising rate.  
1.5 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-Dec-2013
• ICS: 13.080.05 - Examination of soils in general
• Technical Committee: D19 - Water
• Drafting Committee: D19.07 - Sediments, Geomorphology, and Open-Channel Flow

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D6326 − 08 (Reapproved 2014)
Standard Practice for
The Selection of Maximum Transit-Rate Ratios and Depths
for the U.S. Series of Isokinetic Suspended-Sediment
Samplers
This standard is issued under the fixed designation D6326; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This practice covers the maximum transit-rate ratios and
3.1 Definitions—For definitions of terms used in this
depths for selected suspended-sediment sampler-nozzle-
practice, refer toTerminology D1129 andTerminology D4410.
container configurations.
3.2 Definitions of Terms Specific to This Standard:
1.2 This practice explains the reasons for limiting the
3.2.1 approach angle—the angle between the velocity vec-
transit-rate ratio and depths that suspended-sediment samplers
tor of the approaching flow and the centerline of the nozzle.
can be correctly used.
3.2.2 approaching flow—flow immediately upstream of a
1.3 This practice give maximum transit-rate ratios and
nozzles entrance.
depths for selected isokinetic suspended-sediment sampler/
3.2.3 bag sampler—a suspended-sediment sampler that uses
nozzle/container size for samplers developed by the Federal
a flexible collapsible bag as a sample container.
Interagency Sedimentation Project.
3.2.4 compression rate—the rate at which the air is com-
1.4 Throughout this practice, a samplers lowering rate is
pressed in the sample container and is a function of the speed
assumed to be equal to its raising rate.
at which the sampler is lowered in the sampling vertical.
1.5 The values stated in inch-pound units are to be regarded
3.2.5 isokinetic—the conditions under which the direction
as standard. The values given in parentheses are mathematical
and speed of the flowing water/sediment mixture are un-
conversions to SI units that are provided for information only
and are not considered standard. changed upon entering the nozzle of a suspended-sediment
sampler.
1.6 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 3.2.6 maximum transit rate—the maximum speed at which
responsibility of the user of this standard to establish appro-
the sampler can be lowered and raised in the sampling vertical
priate safety and health practices and determine the applica-
and still have the sample collected isokinetically.
bility of regulatory limitations prior to use.
3.2.7 transit rate—the speed at which the suspended sedi-
ment sampler is lowered and raised in the sampling vertical.
2. Referenced Documents
3.2.8 transit-rate ratio—the ratio computed by dividing the
2.1 ASTM Standards:
transit rate by the mean stream velocity in the vertical being
D1129 Terminology Relating to Water
sampled.
D4410 Terminology for Fluvial Sediment
D4411 Guide for Sampling Fluvial Sediment in Motion
4. Summary of Practice
4.1 This practice describes the maximum transit-rate ratios
and depths that can be used for selected isokinetic suspended-
This practice is under the jurisdiction of ASTM Committee D19 on Water and
the direct responsibility of Subcommittee D19.07 on Sediments, Geomorphology,
sediment sampler/nozzle/container configurations to ensure
and Open-Channel Flow.
isokinetic sampling. (Manufacturing differences in the produc-
Current edition approved Jan. 1, 2014. Published March 2014. Originally
tion of sediment samplers may result in some samplers not
approved in 1998. Last previous edition approved in 2008 as D6326 – 08. DOI:
10.1520/D6326-08R14.
collecting a sample isokinetically. It is the users responsibility
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
to ensure through calibration that the sampler does collect a
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
sample isokinetically. Guide D4411 describes a process for
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. checking calibration of suspended-sediment samplers.)
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6326 − 08 (2014)
5. Significance and Use rapidly, the volume of the incoming water is less than the
volume lost to compression. Pressure inside the sampler
5.1 This practice describes the maximum transit-rate ratios
container is less than the hydrostatic pressure outside the
and depths that can be used for selected isokinetic suspended-
sampler. The self regulating properties of the sampler lose
sediment sampler/nozzle/container configurations in order to
control. The intake velocity increases above the stream veloc-
insure isokinetic sampling.
ity. In severe cases, water enters the sampler through the
5.2 This practice is designed to be used by field personnel
air-exhaust vent. If the sampler is raised too rapidly, the air
collecting whole-water samples from open channel flow.
inside the bottle expands and, if not relieved by venting, will
not escape fast enough through the air-exhaust vent. The
6. Background
pressure unbalance causes the intake velocity to be less than
6.1 The distribution of velocity and sediment concentration
the approach velocity. The compression-rate limit is a function
in a sampling vertical is very complex.The velocity of the flow
of the diameter of the nozzle, volume of the sample container,
will generally decrease with depth while the suspended-
andaltitude.Forlargebottleswithsmallnozzlesitcanlimitthe
sediment concentration will normally increase with depth in a
vertical transit rate to less than 3 % of the mean stream
vertical. For a sediment sampler to collect a representative
velocity. Table 1 lists the maximum transit-rates ratios for
volume, the water-sediment mixture must enter the nozzle
commonly used combinations of sampler nozzle and container
without undergoing a change in direction or speed. Ideally, the
sizes.
water must enter the nozzle at the same velocity as the
6.4.3 Because no air is contained inside of the bag, the
approaching flow. When the velocity is unchanged upon
compression rate limit does not apply to bag samplers.
entering the nozzle, the condition is termed isokinetic. Depth-
6.5 Edwards and Glysson discuss the proper use of the
and point-integrating samplers sample isokinetically only if
samplers and transit-rate ratios for some of the more common
their nozzles point directly into the flow and the samplers are
combinations used by the US Geological Survey (USGS).
used within certain ranges of depths. Depth-integrating sam-
Because of difficulties in maintaining a slow transit rate, the
plers also operate isokinetically only when their vertical transit
USGS does not recommend using the USD-77 sampler.
rate is within a given range.
6.6 Based on compression, isokinetic inflow rates, and
6.2 If the velocity of the water-sediment mixture entering
limitsonsamplevolumestopreventoverfilling, themaximum
the nozzle exceeds that of the approach velocity, the sample
depth that any rigid container can be lowered to is about 15 ft
sediment concentration is smaller than the concentration of the
(4.572 m) (FISP). If the sampler is lowered below the
approaching flow. Decreasing the velocity in the nozzle com-
maximum depth limit, the bottle overfills.As shown in Table 1,
pared to the approach velocity will cause the sample sediment
the maximum depth dep
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