Humboldt H-3383L Humboldt Specific Gravity Flask (Phunque Flask) User Manual
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The Procedure
Step 1 When using normal weight aggregate, weigh out 1200 +/- 10 grams
of oven-dry sand or 5000 +/- 50 grams of coarse aggregate to be
tested. Make sure that the sample accurately represents the mate-
rial to be evaluated. If testing lightweight aggregate, reduce the
amount of material weighed out to 600 +/- 10 grams.
Step 2 Fill the flask approximately 1/2 full, by height, with distilled water.
Step 3 Measure out, but do not add yet, approximately 250 g (8.82 ounces)
of distilled water.
Note: The water will probably need to be adjusted for the individual flask
being used. It is important that during the filling process, the
combined initial volume of water and the dry soil do not plug the
neck of the flask. Therefore, the following procedure is intended
to allow sufficient water for the aggregate to become completely
submerged, but to not rise into the narrow neck of the flask.
Holdback water is then added to bring the initial water level after
all of the aggregate and the holdback water has been added into
the calibrated portion of the neck.
Step 4 Dry the neck of the flask with a dry, absorbent swab.
Note:
If the neck is not completely dry, then the finer portions of the
sample will get clogged up on the water droplets, and tend to plug
the neck of the flask as the sample is being poured in. It is recom-
mended that an outside funnel not be used. The sand has a ten-
dency to plug the smaller hole of the funnel, where it typically pours
through the built-in funnel without plugging.
Step 5 Pour the aggregate sample into the flask as quickly as possible,
but without plugging the neck.
Step 6 Start the timer immediately when the first "stone" hits the water in
the flask.
Step 7 After all of the sample has been poured into the flask, immediately
pour in the holdback water measured out in Step 3 so that the final
water level is sufficiently far up the calibrated neck to allow for
accurate readings while the water level drops to its anticipated final
level, being careful not to shake or agitate the flask and contents.
Step 8 Take the initial reading 30 seconds after the first particle has entered
the water.
Step 9 Place the flask on a scale and obtain the total weight of the flask,
aggregate and water.
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