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A number in parentheses indicates the year of last reapproval. This standard has been approved for use by agencies of the U. Department of Defense. Mercury, orits vapor, may be hazardous to health and corrosive tomaterials. Caution should be taken when handling mercury andmercury containing products. No other units of measurement are included in thisstandard. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.
Specific warningstatements are given in Section 7. Referenced Documents2. Summary of Test Method4. Therelative density specific gravity or density is then calculatedfrom this weight and the previously determined weight ofwater that is required to fill the pycnometer at the sametemperature, both weights being corrected for the buoyancy ofair.
Significance and Use5. Current edition approved Nov. Published December Originallyapproved in Last previous edition approved in as D—93 DOI: United States A standardized platinum resistancethermometer may also be used, and offers the best means forobserving minute temperature changes in the bath.
Whichevermeans are available, it must be realized that for most hydro-carbons the density coefficient is about 0. Mechanical balances should have sensitivity which causesthe pointer to be deflected 2 or 3 scale divisions per 1 mg whencarrying a load of 30 g or less on each pan. The balance shouldbe located in a room shielded from drafts and fumes and inwhich the temperature changes between related weighings empty and filled pycnometer do not cause a significantchange in the ratio of the balance arms.
Otherwise weighingsshall be made by the method of substitution, in which thecalibrated weights and pycnometer are alternately weighed onthe same balance pan. The same balance shall be used for allrelated weighings. The same set of weights shall be used for thecalibration of the pycnometer and the determination of densi-ties. Reagents and Materials7. Use ad-equate ventilation. Avoidbuildup of vapors and remove all sources of ignition, especiallynon-explosion proof electrical apparatus.
SulfuricAcid — Warning—Causes severe burns. A recognized car-cinogen. Do not get in eyes, or on skin or clothing. Preparation of Apparatus8. Chromic acid solution Warning—See 7.
However, surfactant cleaning fluids havealso been used successfully. Mount the apparatus firmly andconnect the trap to the vacuum.
Warm the necessary amount ofcleaning acid in the beaker, place the pycnometer on theground joint, and evacuate by opening the stopcock to vacuum.
Remove the acid from thepycnometer by evacuation, empty the acid from the trap, andflush the pycnometer with water. Cleaning should be made inthis manner whenever the pycnometer is to be calibrated orwhenever liquid fails to drain cleanly from the walls of thepycnometer or its capillary. Ordinarily, the pycnometer may be3The sole source of supply of the pycnometer known to the committee at thistime is Reliance Glass Co. Your comments will receive careful consideration at ameeting of the responsible technical committee,1which you may attend.
Place the pycnometer on the cleaner with theupper hypodermic needle extending upward into thepycnometer, and press the edge of the ground joint on therubber stopper until the vacuum holds it in place.
Draw out allthe liquid or sample. Immerse the lower end of the hypodermictube in a suitable solvent and draw 20 to 25 mL through thepycnometer. Leaving the pycnometer in place, draw air throughit until it is dry. Clean the hypodermic syringe with the sameapparatus. Calibration of Pycnometer9. Repeat until atleast three values agree to NOTE 1—It is convenient to use the lightest of a set of pycnometers asa tare. For best results the treatment and environment of both pycnometerand tare should be identical for some time prior to weighing.
Transfer the sample to the pycnometer through the fillingneedle; avoid trapping air bubbles Warning—Extremelyflammable. Avoid buildup of vapors and remove all sources ofignition, especially non-explosion proof electrical apparatus inthe bulb or capillary of the pycnometer.
If any are present, drawthem into the syringe where possible. Also remove with thesyringe or draw-off needle any liquid above the calibrationmark in the capillary or overflow reservoir. Dry the remainderwith a cotton fiber pipe cleaner or cotton swab which has beendampened slightly with acetone. NOTE 2—For work of highest accuracy on pure compounds, dissolvedair may be removed from the sample by repeated freezing and remeltingof the sample under vacuum in the pycnometer.
Periodically, or before the liquidexpands into the overflow chamber, remove the stopper, raisethe pycnometer sufficiently to expose the calibration mark toview, and readjust the liquid level to the mark by withdrawingliquid through the steel draw-off needle until expansion hasstopped, indicating that the liquid has reached the temperatureof the thermostat. Do not allow the liquid to expand more than10 mm above the calibration mark at any time, to minimizeerrors caused by faulty drainage.
Allow the contents to equili-brate an additional 10 min and draw the level down exactly tothe calibration line, avoiding parallax and using a magnifier, ifnecessary, to obtain good visibility. Remove any liquid adher-ing to the walls above the calibration mark, with the draw-offneedle or pipe cleaner, depending upon the volatility of thesample.
Portions in the overflow bulb may be removed with acotton swab moistened with acetone. Place the pycnometer in or near the balance case for 20min and weigh to the nearest 0.
Thischarge need not be completely dissipated in less than 30 min. The use of about 0. Likewise, if the pycnometer, empty and filled with water forcalibration, is weighed under different air densities a similarcorrection for different air buoyancies shall be applied.
NOTE 3—If this test method is to be used frequently, a considerableamount of calculation can be avoided by use of a gas density balance todetermine the air density. Weigh a sealed mL glass bulb at severaldifferent air densities and plot the weight against the air density.