ASTM D3347-94

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 3347 – 94
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
Flow Rate and Tap Density of Electrical Grade Magnesium
Oxide For Use in Sheathed Heating Elements
This standard is issued under the fixed designation D 3347; 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 brated plug is placed in the receiver tube and the tap density is
read from the scale on the plug at the completion of the test.
1.1 This test method covers the determination of the flow
rate and the tap density which predicts the fill rate and flow rate
5. Significance and Use
of granular electrical grade magnesium oxide used in the
5.1 The flow rate is a measure that indicates how the
manufacturing of sheathed heating elements.
magnesium oxide will perform during the heating element
1.2 This standard does not purport to address all of the
filling operation. A user can correlate the flow rate to his filling
safety concerns, if any, associated with its use. It is the
equipment.
responsibility of the user of this standard to establish appro-
5.2 The tap density is a relative measure of the fill density of
priate safety and health practices and determine the applica-
magnesium oxide powder in a heating element before compac-
bility of regulatory limitations prior to use.
tion. The fill density influences such factors as elongation of
2. Referenced Documents the tube during compaction, final density after compaction, and
thermal conductivity of the compacted magnesium oxide.
2.1 ASTM Standards:
D 2755 Test Method of Sampling and Reduction to Test
6. Apparatus
Weight of Electrical Grade Magnesium Oxide
6.1 Balance, capable of weighing 100.00 6 0.02 g.
3. Terminology 6.2 Flow Rate and Tap Density Testing Machine (Fig. 1 and
Fig. 2).
3.1 Definitions of Terms Specific to This Standard:
6.3 Stopwatch.
3.1.1 fill density, n—the weight per unit volume in grams
per cubic centimetre of electrical grade magnesium oxide in a
7. Sampling
sheathed heating element after the filling operation.
7.1 Obtain the sample of magnesium oxide in accordance
3.1.2 fill rate, n—the rate in inches per minute required to
with Test Method D 2755.
fill a sheathed heating element with electrical grade magnesium
oxide.
8. Machine Setup
3.1.3 flow rate, n—the time in seconds required for a 100 g
8.1 Place the flow rate and tap density testing machine on a
specimen of electrical grade magnesium oxide to flow through
rigid table and level the machine base to ensure the receiver
the orifice of the flow rate and tap density testing machine
tube is held exactly vertical. A bubble level mounted on the
hopper.
machine base has been found to be satisfactory.
3.1.4 tap density, n—the weight per unit volume in grams
8.2 Remove hopper and clean the interior surfaces to ensure
per cubic centimetre of electrical grade magnesium oxide in the
free flow of the magnesium oxide. Remove receiver tube and
receiver tube of the flow rate and tap density testing machine
ensure that no residual magnesium oxide has been retained.
after completion of the test.
Replace receiver tube on machine with the identification
4. Summary of Test Method number facing the operator. Replace the hopper on the machine
and lower into the operating position.
4.1 The flow rate is the time, in seconds, required for a
weighed specimen to flow freely through an orifice into a
9. Procedure
receiver tube that is simultaneously tapped.
9.1 Weigh out a specimen of 100.00 6 0.02 g of magnesium
4.2 Following the determination of the flow rate, a cali-
oxide powder as obtained in accordance with 7.
9.2 With the receiver tube and hoper on the operating
This test method is under the jurisdiction of ASTM Committee D-9 on
position, start the machine tapping.
Electrical and Electronic Insulating Materials and is the direct responsibility of
Subcommittee D09.14 on Electric Heating Unit Insulation.
Current edition approved June 15, 1994. Published August 1994. Originally Flow rate and tap density testing machine, available from Boeh Tool and Die
published as D 3347 – 74. Last previous edition D 3347 – 86. Co., 520 McNally Rd., Pittsburg, PA 15226, has been found satisfactory for this
Annual Book of ASTM Standards, Vol 10.02. method.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 3347
9.6 Insert the calibrated plug into the tube, restart the
machine, and allow the tube to tap five times. Read the tap
density from the scale on the plug at the top of the receiver tube
to the nearest 0.01 g/cm .
9.7 Repeat 9.1-9.6 with two additional specimens and aver-
age the results.
10. Report
10.1 Report the following information:
10.1.1 Complete identification of the sample of magnesium
oxide,
10.1.2 Average flow rate, in seconds, and
10.1.3 Average tap density, in g/cm .
11. Precision and Bias
11.1 The precision of this test method has not been deter-
mined. In a well equipped laboratory with trained personnel, it
is expected that triplicate determinations on a single sample of
material with a single piece of equipment should agree to
within 62 % on flow rate and6 0.01 g/cm on tap density. Two
laboratories, each reporting the average of three replicate
FIG. 1 Flow Rate and Tap Density Testing Machine
measurements, should agree to within6 4 % on flow rate and
60.02 g/cm on tap density.
9.3 Pour the specimen into the hopper. At the instant the
11.2 This test method has no bias because the values for tap
specimen begins to flow from the orifice, start the stopwatch.
density and flow rate of magnesium oxide are defined in terms
9.4 Carefully observe the flow of the specimen through the
of this test method.
orifice and stop the stopwatch when the flow ceases. Turn the
machine off. Record the flow
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