Pycnometer

Relative density (specific gravity) of bituminous materials NF T 66-007 ASTM D 70 Pycnometer... 

The density determination may be carried out at the temperature of the laboratory. The liquid should stand for at least one hour and a thermometer placed either in the liquid (if practicable) or in its immediate vicinity. It is usually better to conduct the measurement at a temperature of 20° or 25° throughout this volume a standard temperature of 20° will be adopted. To determine the density of a liquid at 20°, a clean, corked test-tube containing about 5 ml. of toe liquid is immersed for about three-quarters of its length in a water thermostat at 20° for about 2 hours. An empty test-tube and a shallow beaker (e.g., a Baco beaker) are also supported in the thermostat so that only the rims protrude above the surface of the water the pycnometer is supported by its capillary arms on the rim of the test-tube, and the small crucible is placed in the beaker, which is covered with a clock glass. When the liquid has acquired the temperature of the thermostat, the small crucible is removed, charged with the liquid, the pycnometer rapidly filled and adjusted to the mark. With practice, the whole operation can be completed in about half a minute. The error introduced if the temperature of the laboratory differs by as much as 10° from that of the thermostat does not exceed 1 mg. if the temperature of the laboratory is adjusted so that it does not differ by more than 1-2° from 20°, the error is negligible. The weight of the empty pycnometer and also filled with distilled (preferably conductivity) water at 20° should also be determined. The density of the liquid can then be computed. 

An empty wash-bottle, equipped with a two-holed nork, may be interposed between the mouth and the pycnometer for corrosive or poisonous liquids. 

True Density or Specific Gravity. The average mass per unit volume of the individual particles is called the tme density or specific gravity. This property is most important when volume or mass of the filled composition is a key performance variable. The tme density of fillers composed of relatively large, nonporous, spherical particles is usually determined by a simple Hquid displacement method. Finely divided, porous, or irregular fillers should be measured using a gas pycnometer to assure that all pores, cracks, and crevices are penetrated. 

The concentration of distilled glycerol is easily determined from its specific gravity (15) by the pycnometer method (16) with a precision of 0.02%. Deterrnination of the refractive index also is employed (but not as widely) to measure glycerol concentration to 0.1% (17). 

True Specific Gravity. This is deterrnined with an air comparison or conventional glass pycnometer using distilled water as the displacement... 

Sneeffie Gravitv (ASTMD70). For sohd and semisohd asphalts a pycnometer is generahy used and a hydrometer is apphcable to hquid... 

The proof content is determined by the use of a standardized hydrometer with a standardized thermometer. The alcohol content can also be determined by the use of an immersion refractometer, a pycnometer, or a density meter. 

Specific Gravity. The specific gravity is determined by weighing a known volume of sample in a Lipkin bicapiHary pycnometer as described in ASTM Designation D941. 

I = complex impedance, B = conductivity bridge, C = capillary viscometer, P = pycnometer or dilatometer, V = volumetric glassware, I = instrument, U = method unknown... 

A pycnometer is a device used to measure density. It weighs 20.455 g empty and 31.486 g when filled with water (d = 1.00 g/cm3). Pieces of an alloy are put into the empty, dry pycnometer. The mass of the alloy and pycnometer is 28.695 g. Water is added to the alloy to exactly fill the pycnometer. The mass of the pycnometer, water, and alloy is 38,689 g. What is the density of the alloy ... 

A detailed study of the phase relationships in the magnesium oxysulphate cement was carried out by Urwongse Sorrell (1980b). They used X-ray analysis to examine the phases present in the cement, and established the composition of the invariant liquids after equilibration by measuring specific gravity with the aid of a pycnometer. Specific gravities were related to concentration by means of a calibration exercise in which 30 stock solutions of sulphuric acid at concentrations between 0 and 79-5 wt % were prepared with distilled water. 

Having prepared the cements, a number of physical techniques were employed to study them. Porosity was determined by measuring the apparent volume and the solid volume, the former by straightforward linear measurement, the latter using a helium pycnometer. This technique was used to avoid the problems of dissolution that arise when water is used... 

The two principal experimental apparatuses used to determine the density of a liquid are the pycnometer and the vibrating tube densimeter. The pycnometer method involves measuring the mass of a liquid in a vessel of known volume. The volume of the pycnometer, either at the temperature of measurement or at some reference temperature, is determined using a density standard, usually water or mercury. Using considerable care and a precision analytical balance accurate to 10 5 g, it is possible to achieve densities accurate to a few parts in 10s with a pycnometer having a volume of 25 cm3 to 50 cm3. 

It is common to achieve accuracies of 1 part in 105 in using equation (1.1) with pycnometers as small as 5 cm3 and routine measurements can achieve 1 part in 104. However the main sources of error in assigning density to a particular compound in a particular state arise from factors other than the measurment of mass and volume. See Section 1.4.1... 

The gas pycnometer is based on the ideal gas law. A known quantity of gas (characterized by a determined temperature and pressure) is allowed to flow from a calibrated reference volume into a calibrated sample cell containing the solid. A second pressure reading is obtained, and the sample volume is calculated. 

Liquid displacement Glass pycnometers available Tedious Tends to underestimate density Large sample size... 

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