ASTM F1226-89(1994)e1
(Test Method)Standard Test Method for Calibration of Liquid-Borne Particle Counters for Submicrometer Particle Sizing (Withdrawn 2002)
Standard Test Method for Calibration of Liquid-Borne Particle Counters for Submicrometer Particle Sizing (Withdrawn 2002)
SCOPE
1.1 This test method describes a procedure for establishing the sizing accuracy of an automatic, optical liquid-borne single particle counter, using light scattering automatic particle counter (APC). This test method is directed at determining the sizing accuracy of the APC when it is used to measure a challenge suspension of precisely-sized spherical isotropic particles, particularly those sized at and below 1 [mu]m in diameter.
1.2 The particle size parameter that is reported is the equivalent diameter based on the projected area of an isotropic spherical particle of known composition suspended in a liquid that is optically different from the suspended particle. Particles in the size range of 0.1 [mu]m and 5 [mu]m are used for calibration in this procedure.
1.3 This test method does not provide a procedure for APC counting accuracy calibration, since that procedure is available in Practice F658. However, some knowledge of APC maximum concentration capability is necessary in order to avoid introduction of sizing errors as a result of excessive particle concentration during the sizing calibration procedure.
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. For hazard statement, see Section 8.
General Information
Standards Content (Sample)
e1
Designation: F 1226 – 89 (Reapproved 1994)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Calibration of Liquid-Borne Particle Counters for
Submicrometer Particle Sizing
This standard is issued under the fixed designation F 1226; 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.
e NOTE—Keywords were added editorially in September 1994.
1. Scope Substances in the Range of 0.2 to 75 μm by Optical
Microscopy
1.1 This test method describes a procedure for establishing
F 658 Practice for Defining Size Calibration, Resolution,
the sizing accuracy of an automatic, optical liquid-borne single
and Counting Accuracy of a Liquid-Borne Particle Counter
particle counter, using light scattering automatic particle
Using Near-Monodisperse Spherical Particulate Material
counter (APC). This test method is directed at determining the
2.2 Other Standard:
sizing accuracy of the APC when it is used to measure a
ANSI B93.20 Procedure for Qualifying and Controlling
challenge suspension of precisely-sized spherical isotropic
Cleaning Methods for Hydraulic Fluid Power Fluid
particles, particularly those sized at and below 1μ m in
Sample Containers
diameter.
1.2 The particle size parameter that is reported is the
3. Terminology
equivalent diameter based on the projected area of an isotropic
3.1 Definitions of Terms Specific to This Standard:
spherical particle of known composition suspended in a liquid
3.1.1 agglomerate—two or more particles in intimate con-
that is optically different from the suspended particle. Particles
tact that cannot be separated by normal mixing or stirring and
in the size range of 0.1 μm and 5 μm are used for calibration in
the resultant small shear forces generated by such normal
this procedure.
sample handling.
1.3 This test method does not provide a procedure for APC
3.1.2 coincidence—the presence of more than one particle
counting accuracy calibration, since that procedure is available
within the viewing volume of the APC at any time, resulting in
in Practice F 658. However, some knowledge of APC maxi-
the production of a single data pulse from the APC indicating
mum concentration capability is necessary in order to avoid
the presence of a single particle of projected area equal to the
introduction of sizing errors as a result of excessive particle
sum of the areas of those particles present in the viewing
concentration during the sizing calibration procedure.
volume. This is a consistent error that produces a bias that will
1.4 The values stated in SI units are to be regarded as the
increase directly with particle concentration and inversely with
standard. The values given in parentheses are for information
viewing volume dimensions of the APC.
only.
3.1.3 equivalent diameter—the diameter of a sphere of
1.5 This standard does not purport to address all of the
equal projected area or volume to the particle measured and
safety concerns, if any, associated with its use. It is the
with optical properties similar to those of the calibration
responsibility of the user of this standard to establish appro-
material. The particle diameter reported by an APC is based on
priate safety and health practices and determine the applica-
calibration data for the particular APC.
bility of regulatory limitations prior to use. For hazard
3.1.4 saturation level—the pulse counting rate limit for the
statement, see Section 9.
electronic components of a particular APC. At a rate greater
than that limit, the recovery time between pulses is not
2. Referenced Documents
adequate for the APC electronics to clear itself in order to
accept subsequent pulses. As a general rule of thumb, the rate
2.1 ASTM Standards:
limit for pulses arriving at random time intervals, as can be
D 1193 Specification for Reagent Water
expected from particles randomly distributed within a liquid,
E 20 Practice for Particle Size Analysis of Particulate
will be about one-tenth that for uniformly spaced pulses.
This test method is under the jurisdiction of ASTM Committee F-1 on
Electronics and is the direct responsibility of Subcommittee F01.10 on Contamina- Annual Book of ASTM Standards, Vol 14.02.
tion Control. Annual Book of ASTM Standards, Vol 10.05.
Current edition approved May 26, 1989. Published July 1989. Available from American National Standards Institute, 11 West 42nd Street,
Annual Book of ASTM Standards, Vol 11.01. 13th Floor, New York, NY 10036.
F 1226
4. Summary of Test Method 5. Significance and Use
5.1 Manufacturing processes for many electronic, pharma-
4.1 In-line Sensor Calibration—A series of suspensions of
ceutical and mechanical devices require extreme particulate
precisely-sized near-monodisperse spherical calibration par-
cleanliness, both in process liquids and in cleaning operations
ticles are prepared in liquid of composition nearly identical to
where flushing liquids are used. If the liquid contains particu-
that normally flowing through the APC sensor. They are
late material whose size is so large or in concentration
injected into the flowing liquid stream upstream of the sensor
sufficient to interfere with manufacture or subsequent operation
and sized by the sensor. The particle size of the calibration
of the device, then yield and performance are degraded.
particles is determined beforehand, either by microscopic
Accurate measurement of the number and size of particles in
observation as in Practice E 20 for those particles large enough
the liquid must be carried out. Acceptance of data from the
to be so sized, by using NIST standard reference materials (for
APC used to characterize the liquid cleanliness includes
example, SRM 1690 nominal 1 μm or SRM 1691 nominal 0.3μ
reliance on the integrity of the APC for defining the size of any
m), or by using secondary standard calibration material refer-
particle present in samples of liquid passed through the APC.
enced by the supplier. The response of the APC to the
5.2 Although other procedures exist for calibration of APCs
calibration spheres is recorded, in terms of pulse height, along
for liquid-borne particle measurement, the development of
with data that can be used to determine the standard deviation
APCs capable of submicrometre measurement has made it
of the APC output pulse-height distribution. The particle
necessary to prepare a procedure that addresses the special
concentration for this measurement is maintained sufficiently
problems of handling these very small particles. In particular,
low so that the APC coincidence error is less than 3 %, based
the difficulties of cleaning the sample handling equipment are
on the manufacturer’s specification for sensor coincidence
not adequately solved in other test methods.
versus particle concentration levels (See Note 1).
5.3 Care is required to make sure that good sampling is
accomplished from a well-mixed liquid and that no artifacts are
NOTE 1—Do not confuse coincidence error with saturation level. The
introduced in the sample acquisition, storage or handling
coincidence error is a function of concentration only (as long as the
processes. These precautions are necessary both for operation
particle size is insignificant in comparison to the sensing zone size), while
the counting rate is a function of both concentration and liquid flow rate. of this test method and for normal APC use.
Thus, it is possible to exceed the saturation level of the electronic system
5.4 Note that materials of equal size but with differential
by using too high a flow rate, even with acceptable concentration in the
refractive index other than that of the calibration particles in
liquid. In addition to the possibility of too high a counting rate for the
water may produce data that differ from that of the calibration
electronic system, note that the higher flow rate will result in faster data
particles.
pulses with short rise times. For electronic systems with limited band-
width, the short rise time pulses will result in distorted data output,
6. Interferences
indicating particles smaller than those actually present.
6.1 Ingestion of miscellaneous debris during this test causes
4.2 Volumetric or Batch-Analyzing Sensor Calibration—A
errors. In the course of testing with in-line APCs, when either
series of suspensions of precisely-sized near-monodisperse
normal liquid flow lines or sample flow tubing has been in use
spherical calibration particles is prepared in clean reagent
for long time periods, or has been inadequately cleaned before
grade water. The particle size of the precision-sized calibration
use, bursts of submicrometre particles may be released during
particles is determined beforehand, either by microscopic
flexing. These may be surface film fragments produced by
observation as in Practice E 20 for those particles large enough
local stress concentration or they may be previously deposited
to be so sized, by using NIST SRM (for example, SRM 1690
particles released by disturbance of the boundary layer during
nominal 1 μm or SRM 1691 nominal 0.3 μm), or by using
flexing. When testing with batch sampling or volumetric APC,
secondary standard calibration material referenced by the
it is necessary to ensure that ingestion of airborne particles in
supplier. Reagent grade water is flowed through the APC at it’s
size ranges near to those in use does not occur during the test.
rated flow rate by pumping through a membrane type filter of
Operation in an environment controlled by adequate filtration
pore size less than the minimum size that the APC will define.
is required. Use either a horizontal or a vertical flow clean
The stream of clean water is passed into an open container that
bench. Make sure that any liquid containers, closures or tubing
is connected directly to the APC inlet port. The APC outlet port
used in storing, mixing, diluting, transporting, etc., the fluid
may be used as the supply point for the pump filter system. The
samples are clean. Adherence to the requirements of ANSI
entire assembly is maintained in an ultra clean environment. A
B93.20 is recommended to state definitively the cleanliness of
suspension of the calibration material is added to the open
these items.
container and the particles in that material are sized by the
6.2 The presence of air or vapor bubbles during this test
APC. The response of the APC to the precision spheres is
causes erroneous data. When in-line measurements are being
recorded, in terms of pulse height, along with data that can be
made, make sure that the liquid is under sufficient pressure to
used to determine the standard deviation of the APC output
cause such bubbles to remain in solution, or make sure that a
pulse-height distribution. The particle concentration for this
bubble control trap is used. When the calibration particle
measurement is maintained sufficiently low so that the APC
suspension has been prepared, it is necessary to mix the
coincidence error is less than 3 %, based on the manufacturer’s material well in order to ensure that the particles are uniformly
specification for sensor coincidence versus particle concentra-
distributed throughout the sample before removing any ali-
tion levels (See Note 1). quots from that sample. If a surface active dispersant has been
F 1226
added to aid in mixing and dispersion, then the mixing process
may add persistent air bubbles that must be removed before
passing the particle suspension through the APC. Diagnosis
and control are discussed in the appendix.
6.3 Since the APC is a high sensitivity electronic device, it
may be affected by radio frequency or electromagnetic inter-
ference. Take precautions to ensure that the test area environ-
ment does not exceed the radio frequency interference, elec-
tromagnetic interference, (RFI-EMI) capabilities of the APC.
Electronic or operational verification can be made, such as
indication of acceptable background particle count data levels
when verified clean liquid is in the APC sensing volume.
7. Apparatus
7.1 Clean Sample Containers, a supply of glass bottles, 50
to 100 mL, with either screw closure gasketed with liquid-
FIG. 2 Recirculating, Filtered Flow System
compatible polymer liner or compatible snap-on polymer
closure and cleaned in accordance with definitions of ANSI
1003 to 10003 is recommended. The microscope should have
B93.20.
a mechanical stage capable of controlled motion in the X and
7.2 Graduated Cylinder, 100-mL, glass, cleaned in accor-
Y directions. A linear eyepiece reticle should be provided that
dance with definitions of ANSI B93.20.
can be calibrated using a stage micrometer with 10-μm
7.3 Clean Wash Bottle—A wash bottle of at least 500-mL
divisions that can be traced to the NIST. Kohler-type bright-
capacity, filled with clean liquid is needed. Use the liquid in
field illumination should be used to view particles 1 μm in
which the calibration particles are to be suspended. A pressur-
diameter and larger.
ized container with a filter of pore size smaller than the most
sensitive calibration size is preferred.
8. Reagents and Materials
7.4 Dispersing System—An ultrasonic cleaner rated at 30 to
8.1 Purity of Reagents—Reagent grade chemicals shall be
60 W with a 1-L tank is recommended for dispersion or
used in all tests. Unless otherwise specified, it is intended that
deagglomeration, or both, of the calibration particles for
all reagents shall conform to the specifications of the Commit-
suspension.
tee of Analytical Reagents of the American Chemical Society,
7.5 Syringes—Glass syringes, 5-mL capacity, fitted with
where such specifications are available. Other grades may be
standard needle for use in injecting calibration particle suspen-
used, provided that it is first ascertained that the reagent is of
sion into the liquid stream upstream of the APC are needed.
sufficiently high purity to permit its use without lessening the
Use a separate syringe for each calibration particle suspension.
accuracy of the determination.
7.6 Septum-Fitted Connector—Use a special connector, fit-
8.2 Clean Liquid—Approximately 500 mL of the liquid is
ted with a septum for injection of calibration suspension for
required in which the calibration particles shall be suspended
in-line APCs. See Fig. 1 for construction and installation
for this test. The liquid should have been prefiltered through a
directions.
filter of 0.2 to 0.45-μm pore size and stored in a clean container
7.7 Recirculating, Filtered Flow System—A flow system,
before placing it in the clean wash bottle from which it will be
fitted with a self-priming liquid pump and me
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