Hydrometer Method

Note The hydrometer is calibrated at 67°F (19.4°C). If the suspension temperature is above 67°F, the correction is added, and if below, the correction is subtracted. The correction is equal to the difference between the experimental temperature and 67°F, multiplied by 0.2. 

Calculate the percentage of sand, silt and clay and determine the textural class using ISSS textural triangle. 

Working temperature for 4 minute observation = c Corrected hydrometer reading at 4 minutes = d Hydrometer reading at 2 hours = e Working temperature for 2 hours observation = f 

Corrected hydrometer reading at 2 hours = g Amount of silt plus clay = d g Amount of clay = g g, 

It is to be kept in mind that the shortcoming of this method is the lack of any account of the content of organic matter of soil. 

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Density Variation Gravimetric HYDROMETER METHOD Ths suspension of a powder is prepd as for other sedimentation... 

DIVER METHOD- This is a modification of the hydrometer method. Variation in effective density i and hence concn, is measured by totally immersed divers. These are small glass vessels of approximately streamline shape, ballasted to be in stable equilibrium, with the axis vertical, and to have a known density slightly greater than that of the sedimentation liq. As the particles settle, the diver moves downwards in hydrodynamic equilibrium at the appropriate density level. The diver indicates the position of a weight concn equal to the density difference between the diver and the sedimentation liq. Several divers of various densities are required, since each gives only one point on the size distribution curve... 

In using the hydrometer, it must be remembered that the change of density recorded by the hydrometer is not of a particular cross section of the sedimentation cylinder, but depends upon the depth to which the hydrometer is immersed. The hydrometer method can be applied only to suspensions which are of very small size since rapid changes in density of the suspension cannot be read on the hydrometer. ... 

Note that the hydrometer method of particle-size determination is useful for sizes usually below 200 U. S.-sieve sizes. Above this range the material may be sized by sieves, although certainty should be made that agglomerations do not exist. 

The accuracy of the hydrometer method for particle-size measurement is obviously dependent upon some mean distance along its bulb which is taken as a reference point. Along the entire submerged stem and bulb the density of the concentration and the size-distribution of particles are constantly changing. Their reference point may be determined as follows Let L be the distance from the surface of the suspension to the volume center of the hydrometer then if the submerged part of the stem is neglected... 

In using the hydrometer method for determining particle-size, special care should be taken to make due provision for temperature change. The amount of labor involved may be reduced by compiling tables of the constant term in Eq (4-15) and the term p/(p — p0) in Eq (4-16). Tables of p/(p — po) and p for water are given in the appendix. 

Schweyer (1942) compared various methods of particle-size measurement (except centrifuging). He found excellent agreement between pipette and hydrometer methods. He considers the former the best method for determining the particle-m/.c distribution of sub-sieve material by sedimentation, and prefers the hydrometer as a rapid control procedure. 

Comments on the hydrometer method of mechanical analysis." Public Roads, 14 93-105. 

The hydrometer method is simpler in that the density of the suspension, which is related to the concentration, is read directly from the stem of the hydrometer while the depth is determined by the distance of the hydrometer bulb from the surface (ASTM Spec. Pub. 234, 1959). The method has low resolution but is widely used in soil science studies. 

British Standard 1377, The Hydrometer Method of Particle Size Measurement, 384... 

API gravity or density or relative density can be determined using one of two hydrometer methods (ASTM D-287, ASTM D-1298). The use of a digital analyzer (ASTM D-5002) is finding increasing popularity for the measurement of density and specific gravity. 

Specific gravity has no relation to burning quality but is a useful aid in checking consistency of production of a particular grade. The specific gravity of kerosene can be determined very conveniently by the hydrometer method (ASTM D-1298, IP 160). 

Textural analysis was conducted using temperature-controlled water baths and the Bouyoucos hydrometer method ( 8) with 2 modifications. First, soil samples were agitated for 20 seconds with plastic plungers instead of mixing the soil by inverting the container, and second, the clay suspension was not washed and sieved to determine fractional sizes. Organic matter percentages were determined with a dichromate reduction method (9). Electrical conductivity (ec) and pH were measured from the saturation extract of... 

There are two methods for the determination of density that are popular with crude oil chemists. The first is the hydrometer method. The hydrometer is a glass body, which is dipped into the sample. After a short equilibration time, it will float vertically at a certain level. This level results from when the mass of the hydrometer is equal to the buoyancy effect. The higher the density of the sample, the less the hydrometers will sink into the sample. The level of equilibrium shows the density on the calibrated scale. An example of density determination is shown in Figure 2.64. 

The hydrometer method is the simplest and fastest one. This method only has one disadvantage, and that is that the hydrometer usually has a very small measuring range. This requires many hydrometers with different measuring ranges for the determination of the density of a sample with an unknown density. 

ASTM Method D 1298-67, Density, Specific Gravity or API Gravity of Crude Petroleum or Liquid Petroleum Products by Hydrometer Method, ASTM Standards Book, Part 17—Petroleum Products, American Society for Testing and Materials, Philadelphia. 

Soil Particle-Size Analysis. The hydrometer method was used to perform a mechanical analysis of the soils (11). 

Hydrometer method for liquid industrial chemicals gives specific gravity in metric system of units. Special standards exist for halogenated compounds." ... 

ASTM D287 Test Method for API Gravity of Crude Petroleum and Petroleum Products (Hydrometer Method)... 

This industry standard that is based on ASTM D287/1298, is the single most utilized crude property measurement for making crude purchases. It is quite common for measurements to range from values in the low teens (asphaltic crude) to those having values in the 50 s (condensates). While this test normally is done by the hydrometer method and is simple to perform, it does have some crucial steps that need to be performed. The first step is to insure that the crude aliquot taken is representative. API is measured along with the temperature of the cmde that is then converted to an API at 60 °F (the industry standard). 

This is the most common measurement performed on petroleum products density is expressed in terms of API gravity. This measurement determines the weight of a crude oil per imit volume at 60°F, normally measured by the Hydrometer method ASTM D 287. 

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