Rapid Determination of Specific Gravity of liquids under Pressure J. I. LACEY Hooker Electrochemical Company, 'Viagara Falls, S. Y . LIQUID FROM CYLINDER
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Figure 1. Apparatus for Determining Density of Liquid Chlorine
METHOD for the rapid determination of the specific gravity
A of a liquid under pressure at various temperatures involves
placing the sample in a high-pressure vessel that is fitted with a sight glass and reading the specific gravity by means of a hydrometer floating in the liquid. Thi. method has been used to check the densities of commercial liquid chlorine.
Apparatus. The sample was held in the case of a Fischer and Porter armored, horizontal line flow rotameter, modified as described (see Figure l ) . The metering tube, gaskets, and float were removed, the bottom outlets were blanked off, and a well line and a gas outlet were provided through the top flange. The connections were made so that either liquid or gas could be withdrawn or charged. -5, -10" to +llO" C. thermometer subdivided t o 1" C. was suspended in the rotameter case, so that the bulb and part of the stem, but mt the calibration, a-ere immersed in liquid chlorine 1% hen the vessel was half full. -10 to 200 pounds per square inch silver diaphragm pressure gage was provided on the gas phase A hydrometer was placed in the case before filling it with chlorine, and it floated in the liquid after filling. To cover the range indicated, it was necessary to use two hydrometers, 1.300 to 1.400 and 1.400 t o 1.500 specific gravity a t 60" F : the scale on each hydrometer was divided into 100 parts. When the gravity changed from 1.399 t o 1.401 it was necessary to expel the sample, change hydrometer, and then put a frebh sample into the vessel. The temperature was controlled by means of a water bath, the level of which n-as kept just below the level of the chlorine in the vessel. Procedure. A cylinder (100 or 150 pounds] of commercial liquid chlorine nas connected to the well line and inverted. Liquid chlorine was then run into the vessel until it was half full. During the filling, sufficient gas was vented to allow the liquid to enter, but no special effort was made to eliminate all air from the system. The temperature of the water bath mas raised to 50" C. and allowed to cool slowly. The testing equipment was located out of doors, and radiation to the atmosphere was the source of cooling except in the extreme lolver range, n here ice water n-as occasionally used. The temperature and specific gravity n-ereread at frequent intervals. The vessel & a smoved gently between readings to ensure a uniform liquid temperature. At the end of the determination, the instruments were checked against Bureau of Standards instruments and found to be accurate jvithin the limits to vihich they could be read. This method may be adapted to other liquids under pressure, providing the pressure does not collapse the instrument's. The liquid being tested must not appreciably attack the confining vessel or instruments. In this instance the confining vessel was a high-pressure rotameter case, but any vessel of appropriate dimensions having a suitable sight glass may be used. RECEIVED March 2 8 , 1947.
Nomograph for Particle Size Determination with the Sharples Supercentrifuge ELERISGTOX S-IUNDERS, Monsanto Chemical Company, Merrimac Division, Everett, Mass.
HE Sharples supercentrifuge has been used for the deterTmination of particle size and particle distribution in colloidal systems (2-6). Mathematical relations for calculating the size of particles sediinented out under definite operating conditions have been presented (3, 4). Since these calculations are somewhat laborious, graphical methods have been found convenient. Fancher, Oliphant, and Houssiere (2)have presented an alignment chart, but this construction does not consider several variablbs and requires a nerr chart for each system under consideration. An alignment chart has also been presented for the Svedberg ultracentrifuge (7). I t is believed, therefore, that the following nomograph, which is applicable to any system and can be applied t o centrifuges of varying dimensions with a simple correction, willsimplify these calculations still further. Hauser and Lynn (3) have developed methods for calculating the size of particles deposited by the supercentrifuge under definite operating conditions by assuming that the particles obey
Stokes' law, and that the flow parallel t o the rotatory axis streamlined. Their equation is expressed as:
where
Y
L
= vertical distance of deposition of particle of given
size in cm., measured from bottom of centrifuge bowl Q = rate of feed of suspension, cc. per second K , = function of construction of bowl and equal to:
RZ = distance from axis of rotation to bowl wall, cm.
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