ASTM D6057-96

Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Phase Contrast Microscopy

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 μm in length, less than 3 μm in width, an 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 um 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.  
1.5 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: 09-Dec-1996
• Technical Committee: D22 - Air Quality
• Drafting Committee: D22.04 - Workplace Air Quality

Relations

• Replaced By: ASTM D6057-96(2001)e1 - Standard Test Method for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment by Phase Contrast Microscopy
• Effective Date: 10-Dec-1996
• Referred By: ASTM D6058-96(2016) - Standard Practice for Determining Concentration of Airborne Single-Crystal Ceramic Whiskers in the Workplace Environment
• Effective Date: 10-Dec-1996

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 6057 – 96
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 D 6057; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method covers the sampling methods and 2.1 ASTM Standards:
analysis techniques used to assess the airborne concentration of D 1193 Specification for Reagent Water
single-crystal ceramic whiskers (SCCW), such as silicon car- D 1356 Terminology Relating to Sampling and Analysis of
bide and silicon nitride, which may occur in and around the Atmospheres
workplace where these materials are manufactured, processed, D 4532 Test Method for Respirable Dust in Workplace
transported, or used. This test method is based on the collection Atmospheres
of fibers by filtration of a known quantity of air through a filter. D 6056 Test Method for Determining Concentration of
The filter is subsequently evaluated with a phase contrast Airborne Single-Crystal Ceramic Whiskers in the Work-
microscope (PCM) for the number of fibers meeting appropri- place Environment by Transmission Electron Microscopy
ately selected counting criteria. This test method cannot D 6058 Practice for Determining Concentration of Airborne
distinguish among different types of fibers. This test method Single-Crystal Ceramic Whiskers in the Workplace Envi-
may be appropriate for other man-made mineral fibers ronment
(MMMF). D 6059 Test Method for Determining Concentration of
1.2 This test method is applicable to the quantitation of Airborne Single-Crystal Ceramic Whiskers in the Work-
fibers on a collection filter that are greater than 5 μm in length, place Environment by Scanning Electron Microscopy
less than 3 μm in width, and have an aspect ratio equal to or E 691 Practice for Conducting Interlaboratory Study to
greater than 5:1. The data are directly convertible to a Determine the Precision of a Test Method
statement of concentration per unit volume of air sampled. This
3. Terminology
test method is limited by the diameter of the fibers visible by
3.1 Definitions:
PCM (typically greater than 0.25 μm in width) and the amount
and type of coincident interference particles. 3.1.1 analytical sensitivity, n—airborne fiber concentration
represented by a single fiber counted in the PCM.
1.3 A more definitive analysis may be necessary to confirm
the identity and dimensions of the fibers located with the PCM, 3.1.1.1 Discussion—Although the terms fiber and whisker
are, for convenience, used interchangeably in this test method,
especially where other fiber types may be present. Such
techniques may include scanning electron microscopy (SEM) whisker is correctly applied only to single-crystal fibers
or transmission electron microscopy (TEM). The use of these whereas a fiber may be single- or poly-crystalline or may be
noncrystalline.
test methods for the identification and size determination of
SCCW is described in Practice D 6058 and Test Methods 3.1.2 aspect ratio, n—the ratio of the length of a fiber to its
width.
D 6059 and D 6056.
1.4 The values stated in SI units are to be regarded as the 3.1.3 fiber, n—for the purpose of this test method,an
elongated particle having a length greater than 5 μm, a width
standard. The values given in parentheses are for information
only. less than 3 μm, and an aspect ratio equal to or greater than 5:1.
3.1.4 man-made mineral fiber, n—any inorganic fibrous
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the material produced by chemical or physical processes.
3.1.5 single-crystal ceramic whisker, n— a man-made min-
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- eral fiber that has a single-crystal structure.
3.2 For definitions of other terms used in this test method,
bility of regulatory limitations prior to use.
see Terminology D 1356.
This test method is under the jurisdiction of ASTM Committee D-22 on
Sampling and Analysis and is the direct responsibility of Subcommittee D22.04 on Annual Book of ASTM Standards, Vol 11.01.
Analysis of Workplace Atmospheres. Annual Book of ASTM Standards, Vol 11.03.
Current edition approved Dec. 10, 1996. Published February 1997. Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 6057
4. Summary of Test Method agglomeration does occur even with these guidelines. Analyze
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
5 only in circumstances where an alternate filter is not available
assembly (1,2). A section of the opaque filter is converted into
and cannot be obtained through resampling (see 10.1.9).
an optically transparent homogeneous specimen using an
acetone vaporizer. The fibers are counted by PCM at a
7. Apparatus and Reagents
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) and the fiber loading is expressed as fibers per
assembly with shrink tape. Reloading of used cassettes is not
square millimetre (f/mm ).
permitted.
5. Significance and Use 7.2 Personal Sampling Pump—Use a portable battery-
operated pump for personal sampling. Each pump must be
5.1 The SCCW may be present in the workplace atmosphere
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
must be free from pulsation. All pumps shall be calibrated prior
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 This test method is based on dimensional considerations
or a non-portable high-volume pump for area sampling. Each
only. As such, it does not provide a positive identification of the
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
NOTE 1—This test method assumes that the analyst is familiar with the
calibrated prior to use (6).
operation of PCM instrumentation and the interpretation of data obtained
7.4 Vinyl Tubing, or equivalent.
using this technique.
7.5 Microscope—Positive phase contrast light, with green
5.3 This test method is not appropriate for measurement of
or blue filter, 8 to 103 eyepiece, and 40 to 453 phase objective
fibers with diameters less than approximately 0.25 μm due to
(total magnification approximately 4003); numerical aper-
visibility limitations associated with PCM. The SEM or TEM
ture = 0.65 to 0.75.
methods may be used to provide additional size information of
7.6 Acetone Vaporizer—A device used to clear the MCE
SCCW if needed (refer to Practice D 6058 for additional
filter by exposure to a small amount of vaporized acetone.
information on the use of these methods).
7.7 Graticule, with standardized 100-μm diameter circular
−3
5.4 Results from the use of this test method shall be reported
field at the specimen plane (calibrated area ’ 7.8 3 10
along with 95 % confidence limits for the samples being
mm ), with the capability to compare diameters and lengths at
studied. Individual laboratories shall determine their intralabo-
3 and 5 μm, respectively, within the field of view.
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
The Walton-Beckett Type G-24 graticule or other equivalent graticules are
6.1 All fibers meeting the dimensional criteria in Section 3
recommended. Graticules designed for the NIOSH 7400 A rules, such as
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
shall be counted.
view and this value shall be used in all calculations.
6.1.1 This test method has been designed to filter air for the
7.8 Phase Shift Test Slide.
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.
particles may obscure fibers by overlay or by discoloration of
7.10 Stage Micrometre, (0.01-mm divisions).
the filter. This situation can be managed by regulating the air
7.11 Tweezers.
volume sampled and thus the filter loading. Fibers should
7.12 Scalpel Blades.
appear separated from other particles to ensure an adequate
7.13 MCE Filters, 25 mm, 0.45 μm and 0.22 μm.
opportunity for their recognition as separate entities in the
7.14 Funnel/Filter Assembly,25mm.
PCM and accurate counting. Some coincident particulate
7.15 Triacetin (glycerol triacetate).
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, PTR Optics, Waltham, MA.
D 6057
7.16 Acetone.
10 = conversion factor.
NOTE 4—Precaution: Acetone is a flammable liquid and requires
NOTE 5—While the desired minimum loading is 100 f/mm , the
precaution not to ignite it accidentally.
minimum loading that has statistical significance is 7 f/mm after blank
correction (1).
7.17 ASTM D1193 Type II Water (particle free).
NOTE 6—Experience has shown that the fiber loading should not
7.18 Purity of Reagents—Reagent grade chemicals shall be
exceed 1300 f/mm (12 fibers/graticule area, average value for all counted
used in all tests. Unless otherwise indicated, it is intended that
fields) for the majority of sampling situations (1).
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 the American Chemical Society where
7 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
D 4532.
high purity to permit its use without lessening the accuracy of
8.6 Carefully remove the cassette from the tubing at the end
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 Collect samples of airborne SCCW on MCE filters using
sampling cassettes and pumps in accordance with Section 7.
NOTE 7—Deactivate the sampling pump prior to disconnecting the
cassette from the tubing.
8.2 Remove the outlet plug from the sampling cassette and
connect it to a sampling pump by means of flexible,
8.7 Submit at least one field blank (or a number equal to
constriction-proof tubing.
10 % of the total samples, whichever is greater) for each set of
8.3 Perform a leak check of the sampling system by
samples. Remove the cap of the field blank briefly (approxi-
activating the pump with the closed cassette and rotameter (or
mately 30 s) at the sampling site, then replace it. The field
other flow measurement device) in line. Any flow indicates a
blank is used to monitor field sampling procedures. Field
leak that must be eliminated before starting the sampling
blanks shall be representative of filters used in sample collec-
operation.
tion (for example, same filter lot number).
8.4 Remove the inlet plug from the sampling cassette to
8.8 Submit at least one unused and unopened sealed blank
eliminate any vacuum that may have accumulated during the
which is used to monitor the supplies purchased as well as
leak test; then remove the entire inlet cap.
procedures used in the laboratory. The sealed blank shall be
8.5 Conduct personal and area sampling as follows:
representative of filters used in sample collection (for example,
8.5.1 For personal sampling, fasten the sampling cassette to
same filter lot number).
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
0.5 and 4 L/min (1). Typically, a sampling rate between 0.5 and
9.1 Ship the samples in a rigid container with sufficient
2.5 L/min is selected (2-5,7). Also see Test Method D 4532.
packing material to prevent jostling or damage. Care shall be
8.5.2 Place area samples on an extension rod facing down at
taken to minimize vibrations and cassette movement.
a 45° angle. Adjust the calibrated flow rate to a value between
NOTE 8—Do not use shipping material that may develop electrostatic
0.5 and 16 L/min (1). Typically, a sampling rate between 1 and
forces or generate dust.
10 L/min is selected (8).
NOTE 9—Shipping containers for 25-mm sampling cassettes are com-
8.5.3 Set the sampling flow rate and time to produce an
mercially available and their use is recommended.
optimum fiber loading between 100 and 1300 f/mm (1,2). The
9.2 Include in the container a list of samples, their descrip-
time of sampling c
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