ASTM D5595-94

Standard Practice for Determining Buoyancy Corrections During Precision Weighing of Low-Density Samples (Withdrawn 1997)

General Information

• Status: Withdrawn
• Withdrawal Date: 09-Sep-1997
• ICS: 17.060 - Measurement of volume, mass, density, viscosity
• Technical Committee: D22 - Air Quality
• Drafting Committee: D22.01 - Quality Control

Standards Content (Sample)

ASTM D5595 94 = 0759530 0553727 T5T
AMERICAN SOCIETY FOR TESTING AND MATERIALS
(#/b Designation: D 5595 - 94
1916 Race St. Philadelphia, Pa 19103
the Annual Book of ASTM Standards. Copyright ASTM
Reprinted Irom
li not listed in the current combined index. will appear in the neai edtion
Standard Practice for
Determining Buoyancy Corrections During Precision Weighing
of Low-Density Samples’
This standard is issued under the fixed designation D 5595; 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 (c) indicates an editorial change since the last revision or reapproval.
3.2 Description of Terms Specijk to ïhis Standard:
1. Scope
3.2.1 balance-precision device that is used to determine
1. I This practice covers the procedures used to determine
the weight or pass of a sample. Such a device usually
true sample mass from scale readings, by determining the
requires ongoing calibration, but users seldom employ a
effective volume of the sample and applying a correction for
correction for buoyancy effects, as presented in this proce-
the effects of the buoyancy of the air in which samples are
dure. It may be a one-pan or two-pan balance, or a device
weighed.
that uses an electronic force measuring system to provide a
I .2 This practice provides the information required to
reading of weight (sometimes displayed us mass).
determine when buoyancy corrections are warranted, and
when they can be safely ignored. DrscussioN-The term balance is usually reserved for devices used
for precision weighing and the term scale for conventional weighing.
1.3 This practice is used whenever a small difference in
mass between two low-density samples (or the same sample
3.2.2 balance, one-pan-balance that employs one pan for
on reweighing) must be determined with a high level of
the sample, plus a balancing system that does not have a
accuracy, to achieve the desired test method accuracy.
volume similar to the sample pan.
1.4 Refer to Practice E 380 in using this practice.
3.2.3 balance, two-pan-balance that employs two pans
or mass.
and precision weights to determine sample weight
NOTE I-Mass difference errors may be a major source of inaccuracy
in methods that do not produce precision results even after careful
DrscussroN-This type of balance is usually less sensitive to buoy-
weighing. The use of this procedure may be warranted, therefore, in test
ancy-effect tare problems than a one-pan balance or electronic scales,
methods that presently display a precision of only I20 %, and may
which do not have similar volumes on each side of the fulcrum.
subsequently display better precision and repeatability, as well as lower
thresholds. 3.2.4 effective volume-volume that is effective in dis-
placing laboratory air, and thus governs the buoyancy force
1.5 This standard does not purport to address all of the
for that sample or component. This buoyancy force is
safety concerns, if any, associated with its use. It is the
modified by any tare buoyancy of the balance, and is thus a
responsibility of the user of this standard to establish appro-
function of both the sample and the balance.
priate safity and health practices and determine the applica-
3.2.5 sample-component (for example; tracer-gas sam-
bility of regulatory limitations prior to use.
pler, tracer-gas source, etc.), piece of material (for example;
filter paper, insulation sample, etc.) or container being
2. Referenced Documents
weighed to a high degree of precision.
3.2.6 sample, constant volume-sample that does not
2. I ASTM Standards:
significantly change its ability to displace air between read-
E 380 Practice for Use of the International System of
ings, even when its mass does change (for example; a sealed,
Units (SI) (the Modem Metric System)2
hollow, metal container).
D 1356 Terminology Relating to Sampling and Analysis of
3.2.7 sample density-sample mass divided by its effec-
Atmospheres3
tive volume.
D 363 I Test Methods for Measuring Surface Atmospheric
3.2.8 sample, variable volume-sample that changes the
Pressure
amount of air that it displaces, as it changes mass (for
D 4230 Test Method for Measuring Humidity with
example; particulate-loaded filter paper).
Cooled-Surface Condensation (Dew-Point) Hygrometer
D 3670 Practice for Determination of Precision and Accu-
4. Summary of Practice
racy of Methods of Committee D-22
4.1 Determine the effective volume of the air displaced by
3. Terminology a sample which is being weighed or reweighed, by measuring
the change in indicated weight of a typical sample, during
3.1 Refer to Terminology D 1356, for definitions of other
large changes in laboratory air density caused by a large
terms used in this practice.
variation in ambient pressure, then use that information in
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