ASTM D6057-96(2006)
(Test Method)Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Phase Contrast Microscopy
Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Phase Contrast Microscopy
SIGNIFICANCE AND USE
The SCCW may be present in the workplace atmosphere where these materials are manufactured, processed, transported, or used. This test method can be used to monitor airborne concentrations of fibers in these environments. It may be employed as part of a personal or area monitoring strategy.
This test method is based on dimensional considerations only. As such, it does not provide a positive identification of the fibers counted. Analysis by SEM or TEM is required when additional fiber identification information is needed.
Note 1—This test method assumes that the analyst is familiar with the operation of PCM instrumentation and the interpretation of data obtained using this technique.
This test method is not appropriate for measurement of fibers with diameters less than approximately 0.25 μm due to visibility limitations associated with PCM. The SEM or TEM methods may be used to provide additional size information of SCCW if needed (refer to Practice D 6058 for additional information on the use of these methods).
Results from the use of this test method shall be reported along with 95 % confidence limits for the samples being studied. Individual laboratories shall determine their intralaboratory coefficient of variation and use it for reporting 95 % confidence limits (1,3,4).
SCOPE
1.1 This test method covers the sampling methods and analysis techniques used to assess the airborne concentration of single-crystal ceramic whiskers (SCCW), such as silicon carbide and silicon nitride, which may occur in and around the workplace where these materials are manufactured, processed, transported, or used. This test method is based on the collection of fibers by filtration of a known quantity of air through a filter. The filter is subsequently evaluated with a phase contrast microscope (PCM) for the number of fibers meeting appropriately selected counting criteria. This test method cannot distinguish among different types of fibers. This test method may be appropriate for other man-made mineral fibers (MMMF).
1.2 This test method is applicable to the quantitation of fibers on a collection filter that are greater than 5 m in length, less than 3 m in width, and have an aspect ratio equal to or greater than 5:1. The data are directly convertible to a statement of concentration per unit volume of air sampled. This test method is limited by the diameter of the fibers visible by PCM (typically greater than 0.25 m in width) and the amount and type of coincident interference particles.
1.3 A more definitive analysis may be necessary to confirm the identity and dimensions of the fibers located with the PCM, especially where other fiber types may be present. Such techniques may include scanning electron microscopy (SEM) or transmission electron microscopy (TEM). The use of these test methods for the identification and size determination of SCCW is described in Practice D 6058 and Test Methods D 6059 and D 6056.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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.
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Designation:D6057–96 (Reapproved 2006)
Standard Test Method for
Determining Concentration of Airborne Single-Crystal
Ceramic Whiskers in the Workplace Environment by Phase
Contrast Microscopy
This standard is issued under the fixed designation D6057; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
1.1 This test method covers the sampling methods and
bility of regulatory limitations prior to use.
analysistechniquesusedtoassesstheairborneconcentrationof
single-crystal ceramic whiskers (SCCW), such as silicon car-
2. Referenced Documents
bide and silicon nitride, which may occur in and around the
2.1 ASTM Standards:
workplace where these materials are manufactured, processed,
D1193 Specification for Reagent Water
transported,orused.Thistestmethodisbasedonthecollection
D1356 Terminology Relating to Sampling and Analysis of
offibersbyfiltrationofaknownquantityofairthroughafilter.
Atmospheres
The filter is subsequently evaluated with a phase contrast
D4532 Test Method for Respirable Dust in Workplace
microscope (PCM) for the number of fibers meeting appropri-
Atmospheres Using Cyclone Samplers
ately selected counting criteria. This test method cannot
D6056 Test Method for Determining Concentration of Air-
distinguish among different types of fibers. This test method
borne Single-Crystal Ceramic Whiskers in the Workplace
may be appropriate for other man-made mineral fibers
Environment by Transmission Electron Microscopy
(MMMF).
D6058 Practice for Determining Concentration ofAirborne
1.2 This test method is applicable to the quantitation of
Single-Crystal Ceramic Whiskers in the Workplace Envi-
fibers on a collection filter that are greater than 5 µm in length,
ronment
less than 3 µm in width, and have an aspect ratio equal to or
D6059 Test Method for Determining Concentration of Air-
greater than 5:1. The data are directly convertible to a
borne Single-Crystal Ceramic Whiskers in the Workplace
statementofconcentrationperunitvolumeofairsampled.This
Environment by Scanning Electron Microscopy
test method is limited by the diameter of the fibers visible by
E691 Practice for Conducting an Interlaboratory Study to
PCM (typically greater than 0.25 µm in width) and the amount
Determine the Precision of a Test Method
and type of coincident interference particles.
1.3 Amore definitive analysis may be necessary to confirm
3. Terminology
theidentityanddimensionsofthefiberslocatedwiththePCM,
3.1 Definitions:
especially where other fiber types may be present. Such
3.1.1 analytical sensitivity, n—airborne fiber concentration
techniques may include scanning electron microscopy (SEM)
represented by a single fiber counted in the PCM.
or transmission electron microscopy (TEM). The use of these
3.1.1.1 Discussion—Although the terms fiber and whisker
test methods for the identification and size determination of
are, for convenience, used interchangeably in this test method,
SCCW is described in Practice D6058 and Test Methods
whisker is correctly applied only to single-crystal fibers
D6059 and D6056.
whereas a fiber may be single- or poly-crystalline or may be
1.4 The values stated in SI units are to be regarded as the
noncrystalline.
standard. The values given in parentheses are for information
3.1.2 aspect ratio, n—the ratio of the length of a fiber to its
only.
width.
1.5 This standard does not purport to address all of the
3.1.3 fiber, n—for the purpose of this test method,an
safety concerns, if any, associated with its use. It is the
elongated particle having a length greater than 5 µm, a width
less than 3 µm, and an aspect ratio equal to or greater than 5:1.
This test method is under the jurisdiction of ASTM Committee D22 on Air
Quality and is the direct responsibility of Subcommittee D22.04 on Workplace
Atmospheres. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2006. Published October 2006. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
´1
approved in 1996. Last previous edition approved in 2001 as D6057-96 (2001) . Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D6057-96R06. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6057–96 (2006)
3.1.4 man-made mineral fiber, n—any inorganic fibrous particles may obscure fibers by overlay or by discoloration of
material produced by chemical or physical processes. the filter. This situation can be managed by regulating the air
3.1.5 single-crystal ceramic whisker, n— a man-made min- volume sampled and thus the filter loading. Fibers should
eral fiber that has a single-crystal structure. appear separated from other particles to ensure an adequate
3.2 For definitions of other terms used in this test method, opportunity for their recognition as separate entities in the
see Terminology D1356. PCM and accurate counting. Some coincident particulate
agglomeration does occur even with these guidelines.Analyze
4. Summary of Test Method
an alternate filter with a reduced loading if the obscuring
4.1 The sample is collected on a mixed cellulose ester condition appears to exceed 15% of the filter area (5).
(MCE) filter by drawing air, using a sampling pump, through
Redeposition of a portion of an overloaded filter is permitted
an open-face 25-mm electrically conductive sampling cassette only in circumstances where an alternate filter is not available
assembly (1,2). Asectionoftheopaquefilterisconvertedinto
and cannot be obtained through resampling (see 10.1.9).
an optically transparent homogeneous specimen using an
7. Apparatus and Reagents
acetone vaporizer. The fibers are counted by PCM at a
magnification of approximately 4003 using the criteria dis-
7.1 Sampling Cassette—Use a 25-mm, electrically conduc-
cussed in Section 11. Results are expressed as a fiber concen-
tive cassette assembly such as a three-piece cassette with an
tration per unit volume of air and a fiber loading per unit area
extension cowl or retainer ring, or both, containing a 0.45-µm
of filter. The airborne concentration is expressed as fibers per
pore size MCE filter and a support pad. Seal the cassette
millilitre(f/mL)andthefiberloadingisexpressedasfibersper
assembly with shrink tape. Reloading of used cassettes is not
square millimetre (f/mm ).
permitted.
7.2 Personal Sampling Pump—Use a portable battery-
5. Significance and Use
operated pump for personal sampling. Each pump must be
5.1 TheSCCWmaybepresentintheworkplaceatmosphere
capable of operating within the range from 0.5 to 4 L/min and
where these materials are manufactured, processed, trans-
continuously over the chosen sampling period (1). The flow
ported, or used. This test method can be used to monitor
mustbefreefrompulsation.Allpumpsshallbecalibratedprior
airborne concentrations of fibers in these environments. It may
to use (6).
be employed as part of a personal or area monitoring strategy.
7.3 Area Sampling Pump—Use a personal sampling pump
5.2 Thistestmethodisbasedondimensionalconsiderations
or a non-portable high-volume pump for area sampling. Each
only.Assuch,itdoesnotprovideapositiveidentificationofthe
pump shall be capable of operating within the range from 0.5
fibers counted. Analysis by SEM or TEM is required when
to 16 L/min and continuously over the chosen sampling period
additional fiber identification information is needed.
(1). The flow shall be free from pulsation. All pumps shall be
calibrated prior to use (6).
NOTE 1—This test method assumes that the analyst is familiar with the
7.4 Vinyl Tubing, or equivalent.
operation of PCM instrumentation and the interpretation of data obtained
using this technique. 7.5 Microscope—Positive phase contrast light, with green
orbluefilter,8to103eyepiece,and40to453phaseobjective
5.3 This test method is not appropriate for measurement of
(total magnification approximately 4003); numerical aper-
fibers with diameters less than approximately 0.25 µm due to
ture=0.65 to 0.75.
visibility limitations associated with PCM. The SEM or TEM
7.6 Acetone Vaporizer—A device used to clear the MCE
methods may be used to provide additional size information of
filter by exposure to a small amount of vaporized acetone.
SCCW if needed (refer to Practice D6058 for additional
7.7 Graticule, with standardized 100-µm diameter circular
information on the use of these methods).
−3
field at the specimen plane (calibrated area ' 7.8 310
5.4 Resultsfromtheuseofthistestmethodshallbereported
mm ), with the capability to compare diameters and lengths at
along with 95% confidence limits for the samples being
3 and 5 µm, respectively, within the field of view.
studied. Individual laboratories shall determine their intralabo-
ratory coefficient of variation and use it for reporting 95%
NOTE 2—The graticule is custom-made for each microscope. Specify
confidence limits (1,3,4). disk diameter needed to exactly fit the ocular of the microscope and the
diameter (millimetres) of the circular counting area (see section 12.2.1).
6. Interferences TheWalton-BeckettTypeG-24graticuleorotherequivalentgraticulesare
recommended. Graticules designed for the NIOSH 7400Arules, such as
6.1 All fibers meeting the dimensional criteria in Section 3
the Walton-Beckett Type G-22, are not recommended.
are not necessarily of the same composition. Since the PCM
NOTE 3—In some microscopes, adjustments of the interocular distance
method does not differentiate based on chemistry or morphol-
will change the tube length and hence magnification of the microscope.
ogy, all fibers in accordance with the definitions in Section 3
Each analyst shall separately measure the diameter of his or her field of
view and this value shall be used in all calculations.
shall be counted.
6.1.1 This test method has been designed to filter air for the 4
7.8 Phase Shift Test Slide equivalent to HSE/NPL.
determination of fiber concentration. However, filtration of air
7.9 Telescope, (ocular phase-ring centering) or Bertrand
also involves collection of extraneous particles. Extraneous
lens.
The boldface numbers in parentheses refer to a list of references at the end of
this test method. The HSE/NPL Phase Shift Test Slide, Mark II.
D6057–96 (2006)
7.10 Stage Micrometer, (0.01-mm divisions).
t = time, min,
7.11 Tweezers.
F = fiber loading, f/mm ,
L
7.12 Scalpel Blades.
Q = sampling flow rate, L/min,
7.13 MCE Filters, 25 mm, 0.45 µm and 0.22 µm. C = estimated concentration of SCCW, f/mL, and
e
10 = conversion factor.
7.14 Funnel/Filter Assembly,25mm.
7.15 Triacetin (glycerol triacetate). 2
NOTE 4—While the desired minimum loading is 100 f/mm , the
7.16 Acetone.(Warning—Acetone is a flammable liquid
minimum loading that has statistical significance is 7 f/mm after blank
and requires precaution not to ignite it accidentally.)
correction (1).
7.17 ASTM D1193 Type II Water (particle free). NOTE 5—Experience has shown that the fiber loading should not
exceed1300f/mm (12fibers/graticulearea,averagevalueforallcounted
7.18 Purity of Reagents—Reagent grade chemicals shall be
fields) for the majority of sampling situations (1).
used in all tests. Unless otherwise indicated, it is intended that
all reagents conform to the specifications of the Committee on 8.5.4 At a minimum, check the flow rate before and after
Analytical Reagents of theAmerican Chemical Society where sampling. If the difference is greater than 10% from the initial
such specifications are available. Other grades may be used, flow rate, the sample shall be rejected. Also see Test Method
provided it is first ascertained that the reagent is of sufficiently D4532.
high purity to permit its use without lessening the accuracy of
8.6 Carefullyremovethecassettefromthetubingattheend
the determination. of the sampling period (ensure that the cassette is positioned
upright before interrupting the pump flow). Replace the inlet
8. Sample Collection
cap and inlet and outlet plugs, and store the cassette.
8.1 CollectsamplesofairborneSCCWonMCEfiltersusing
NOTE 6—Deactivate the sampling pump prior to disconnecting the
sampling cassettes and pumps in accordance with Section 7.
cassette from the tubing.
8.2 Remove the outlet plug from the sampling cassette and
8.7 Submit at least one field blank (or a number equal to
connect it to a sampling pump by means of flexible,
10% of the total samples, whichever is greater) for each set of
constriction-proof tubing.
samples. Remove the cap of the field blank briefly (approxi-
8.3 Perform a leak check of the sampling system by
mately 30 s) at the sampling site, then replace it. The field
activating the pump with the closed cassette and rotameter (or
blank is used to monitor field sampling procedures. Field
other flow measurement device) in line. Any flow indicates a
blanks shall be representative of filters used in sample collec-
leak that must be eliminated before starting the sampling
tion (for example, same filter lot number).
operation.
8.8 Submit at least one unused and unopened sealed blank
8.4 Remove the inlet plug from the sampling cassette to
which is used to monitor the supplies purchased as well as
eliminate any vacuum that may have accumulated during the
procedures used in the laboratory. The sealed blank shall be
leak test; then remove the entire inlet cap.
representativeoffiltersusedinsamplecollection(forexample,
8.5 Conduct personal and area sampling as follows:
same filter lot number).
8.5.1 For personal sampling, fasten the sampling cassette to
the worker’s lapel in the worker’s breathing zone and orient it
9. Transport of Samples
face down. Adjust the calibrated flow rate to a value between
9.1 Ship the samples in a rigid container with sufficient
0.5and4L/min(1).Typically,asamplingratebetween0.5and
packing material to prevent jostling or damage. Care shall be
2.5 L/min is selected (2-5,7). Also see Test Method D4532.
taken to minimize vibrations and cassette movement.
8.5.2 Placeareasamplesonanextensionrodfacingdownat
a 45° angle.Adjust the calibrated flow rate to a value between
NOTE 7—Do not use shipping material that may develop electrostatic
0.5and16L/min (1).Typically,asamplingratebetween1and
forces or generate dust.
10 L/min is selected (8). NOTE 8—Shipping containers for 25-mm sampling cassettes are com-
mercially available and their use is recommended.
8.5.3 Set the sampling flow rate and time
...
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