ASTM D2525-90(2001)
(Practice)Standard Practice for Sampling Wool for Moisture
Standard Practice for Sampling Wool for Moisture
SIGNIFICANCE AND USE
This recommended practice furnishes directions for the sampling of wool of the various forms indicated in Section 1, in order that correct probability statements may be made about the relationship between the sample mean and the population mean. If these statements are to be correct, certain conditions, which are stated, must hold.
This recommended practice requires that a deliberate act of randomization be performed so that all potential sampling units have approximately the same chance of being taken and no sampling unit is deprived of its chance of being taken.
In any case where insufficient information about the variability of the sampling units within the lot is available, directions are given for calculating confidence limits for the sample mean so that a correct probability statement can still be made.
SCOPE
1.1 This practice covers the design of a sampling plan to be used to obtain samples for the determination of the moisture content of grease wool, scoured wool, carded wool, garnetted wool, wool top and intermediate products, and rovings.
1.2 Directions are given for the designation of sampling units, calculation of the number of sampling units required to achieve a preselected precision and confidence level or, alternatively, for calculating the confidence limits for the mean based on the variability of the sample tested.
Note 1--This practice for devising a sampling plan is intended for use in connection with Test Method D1576 or Test Method D2462. The sampling of raw wool for the determination of clean wool fiber present is covered in Practice D1060.
1.3 This standard does not purport to address the safety problems 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
Relations
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:D2525–90(Reapproved 2001)
Standard Practice for
Sampling Wool for Moisture
This standard is issued under the fixed designation D2525; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.1 laboratory sample, n—a portion of material taken to
represent the lot sample, or the original material, and used in
1.1 This practice covers the design of a sampling plan to be
the laboratory as a source of test specimens.
used to obtain samples for the determination of the moisture
3.1.2 lot, n—in acceptance sampling,thatpartofaconsign-
content of grease wool, scoured wool, carded wool, garnetted
ment or shipment consisting of material from one production
wool, wool top and intermediate products, and rovings.
lot.
1.2 Directions are given for the designation of sampling
3.1.3 lot sample, n—one or more shipping units taken at
units, calculation of the number of sampling units required to
random to represent an acceptance sampling lot and used as a
achieve a preselected precision and confidence level or, alter-
source of laboratory samples.
natively, for calculating the confidence limits for the mean
3.1.4 sample, n—(1) a portion of a lot of material which is
based on the variability of the sample tested.
taken for testing or record purposes.
NOTE 1—This practice for devising a sampling plan is intended for use
(2) the group of specimens used, or observations made,
in connection with Test Method D1576 or Test Method D2462. The
which provide information that can be used for making
sampling of raw wool for the determination of clean wool fiber present is
statistical inferences about the population from which they
covered in Practice D1060.
were drawn.
1.3 This standard does not purport to address all of the
3.1.5 sampling unit, n—in wool,aportionofmaterialthatis
safety concerns, if any, associated with its use. It is the
taken at one time from one physical location and that is
responsibility of the user of this standard to establish appro-
combined with similar portions to make up the laboratory
priate safety and health practices and determine the applica-
sample.
bility of regulatory limitations prior to use.
3.1.5.1 Discussion—A sampling unit may or may not have
the same physical size as a specimen. Examples of sampling
2. Referenced Documents
units include: (1) for bulk materials seen as scoured wool, a
2.1 ASTM Standards:
handful of wool conforming to a stated mass range, (2) for
D123 Terminology Relating to Textiles
cored material, a minimum mass of material collected by one
D1060 Practice for Core Sampling of Raw Wool in Pack-
insertion of a coring tool, (3) for sliver, a stated length of
ages for Determination of Percentage of CleanWool Fiber
material, and (4) a single package, such as a ball of top.
Present
3.1.6 specimen, n—a specific portion of a material or a
D1576 TestMethodforMoistureinWoolbyOven-Drying
laboratory sample upon which a test is performed or which is
D2462 Test Method for Moisture in Wool by Distillation
selected for that purpose.
with Toluene
3.1.7 Fordefinitionsofmoisture,moisturecontent,moisture
E122 Practice for Calculating Sample Size to Estimate,
regain, and other textile terms used in this practice, refer to
With a Specified Tolerable Error, the Average for a
Terminology D123.
Characteristic of a Lot or Process
4. Summary of Practice
3. Terminology
4.1 Directions are given for subdividing a lot of material
3.1 Definitions:
into potential sampling units and for providing each potential
sampling unit with its own unique identification.
4.2 Directions are given for calculating the number of such
ThispracticeisunderthejurisdictionoftheASTMCommitteeD13onTextiles,
and is the direct responsibility of Subcommittee D13.13 on Wool and Wool Felt.
sampling units required to give a preselected allowable varia-
Current edition approved Jan. 26, 1990. Published May 1990. Originally
tion at a stated probability level, or for calculating confidence
published as D2525–66T. Last previous edition D2525–76 (1983).
limitsforthesamplemeanobtainedforagivensizeofsample.
Annual Book of ASTM Standards, Vol 07.01.
Annual Book of ASTM Standards, Vol 14.02.
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959, United States.
D2525
4.3 Directions are given for deciding which particular sam- the information in the sample results. In this case, the only
pling units should be chosen to constitute the required lot condition that applies is 6.1.3.
sample. These directions ensure that all potential sampling
7. Procedure
unitshaveapproximatelythesamechanceofbeingselectedfor
7.1 Designate the form and size of the sampling unit,
the lot sample.
bearing in mind the conditions and precautions discussed in
Sections 5 and 6. Whenever possible, make the size of the
5. Significance and Use
sampling unit and specimen the same.
5.1 This recommended practice furnishes directions for the
7.1.1 The designation of the sampling unit depends on the
sampling of wool of the various forms indicated in Section 1,
form of the material and on the method to be used for making
in order that correct probability statements may be made about
measurements on the sample. The material to be sampled may
the relationship between the sample mean and the population
existinoneofthreebasicforms:bulkmaterialsuchasscoured
mean. If these statements are to be correct, certain conditions,
wool or picked blends of wools, packaged material such as
which are stated, must hold.
baled wool, or material put up in the form of packages within
5.2 Thisrecommendedpracticerequiresthatadeliberateact
packagessuchasballsoftopwithincasesorbales.Themethod
of randomization be performed so that all potential sampling
of measurement may require a specimen as large as a whole
units have approximately the same chance of being taken and
package of material, or as small as a few grams of material.
no sampling unit is deprived of its chance of being taken.
7.1.2 Where the material to be sampled exists in some bulk
5.3 In any case where insufficient information about the
form,suchasscouredwool,orablendthathasbeenpickedand
variability of the sampling units within the lot is available,
stored in a bin, the designation of a sampling unit will depend
directions are given for calculating confidence limits for the
uponthemechanicsofdrawingthesample.Ifhandsamplingis
samplemeansothatacorrectprobabilitystatementcanstillbe
the method employed, the sampling unit will be a handful of a
made.
certain specified size. Whenever possible, the size of a sam-
pling unit should be made to coincide with the size of the
6. Preliminary Conditions
specimen required by the method of measurement because the
6.1 If it is desired to calculate a sample size to achieve a
random variations observed in the test results are then directly
preselected precision at a preselected level of confidence,
applicable to the sampling units.
knowledge of the variation of the moisture content is neces-
7.1.3 When the material to be sampled exists in the form of
sary.
packages such as baled wool or packages within packages,
6.1.1 The test method to be used must be the same method
such as balls of wool top in cases or bales, the sampling unit
that was used to derive any prior information with respect to
can be either an entire package or some portion of a package,
the variability of the moisture content.
depending upon the size of the specimen required.
6.1.2 The sampling unit must be the fundamental unit in
7.2 Identify each potential sampling unit in the lot by
termsofwhichthevarianceisexpressed.Inotherwords,ifthe
numbering, coding, using geometrical coordinates, or by any
sampling unit is chosen to be a 25-g handful of bulk material
other systematic means. It is important that by some means or
ora4-yd(3.65-m)lengthofsliver,thenthevarianceusedmust
other, all potential sampling units must be furnished with their
be the number that expresses the variability of these units, and
ownuniqueidentificationsothatnoneisdeprivedofitschance
the number of sampling units which is calculated will be the
of being sampled.
number of such units required. The sampling unit is not
7.2.1 In designing a sampling plan, it is necessary to devise
necessarily the same thing as a specimen.
a method for assigning to every potential sampling unit in the
6.1.3 The lot designated for sampling must be statistically
lot a unique identification. This is a relatively simple task in
homogeneous.Thisisequivalenttosayingthatthelotshallnot
thoseinstanceswherethesamplingunitsarediscretepackages,
be composed of a mixture of two or more parts, the moisture
such as might be the case with balls of top if an entire ball is
contentofwhichisdistributedsufficientlydifferentlythatifthe
to be the sampling unit.
moisture content of the entire lot were measured, a plot of the
7.2.2 With material in bulk form or with packaged material
moisture content versus the number of sampling units would
in which the sampling unit is to be only a portion of the
show a curve having more than one peak. (SeeAppendix X1.) package, it is not as easy to identify uniquely each potential
IfthetestgiveninAppendixX1leadstotheconclusionthatthe
sampling unit, and some method of approximating the ideal
lot cannot be considered to be statistically homogeneous, then situation must be devised. See, for example, the instructions
itshouldbesubdividedintogroupsthatarehomogeneous.The
given in Practice D1060.
pattern of runs found may indicate what the subgroups should 7.2.3 For materials in loose bulk form, considerable inge-
be.
nuity and imagination may be required to effect a proper
6.1.4 The magnitude of the variation of moisture content identification of the potential sampling units.
within the homogeneous lot must be known.The magnitude of
7.3 Option 1—This procedure is available for those in-
the variation is usually expressed as the standard deviation, stanceswhereinformationissufficienttoenablethecalculation
although the range may also be used.
of sample size required for a specified allowable variation and
6.2 If insufficient knowledge is available to ensure meeting probability level.
the above conditions, a sample of convenient size may be 7.3.1 If the allowable variation and probability level are not
selected and confidence limits calculated for the mean using stated in the applicable material specification or otherwise
D2525
established, determine for these factors values mutually agree-
Probability Level,% tt
able to all parties interested in the test results.
90 1.645 2.706
7.3.2 Wheneverthematerialbeingtestedhasbeenproduced
95 1.960 3.842
under statisically controlled conditions a
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.