Piezometer


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piezometer

[‚pē·ə′zäm·əd·ər]
(engineering)
An instrument for measuring fluid pressure, such as a gage attached to a pipe containing a gas or liquid.
An instrument for measuring the compressibility of materials, such as a vessel that determines the change in volume of a substance in response to hydrostatic pressure.

Piezometer

 

a device used to measure the change in volume of substances that occurs as a result of hydrostatic pressure. Piezometric measurements are used to obtain data on the compressibility, or volume elasticity, of substances and to investigate phase diagrams, phase transitions, and other physical and chemical processes.

The design of piezometers is determined by the range of pressures and temperatures to be applied, by the state of aggregation of the substance to be investigated (gaseous, liquid, or solid), and by the compressibility of the substance. There are two main types of piezometers. In those of the first type, the mass M of the substance being investigated is constant, but its volume V changes with pressure ρ and temperature T. Such piezometers are thick-walled vessels in which pressure is applied to solids, liquids, or gases in order to determine their compressibility. During the experiment, the relationship between the change in V and that in ρ is measured; the temperature of the substance is usually kept constant. In piezometers of the second type, M is a variable quantity, and the volume of the vessel containing the substance to be studied is constant. Here, an allowance must be made for any deformation in the piezometers caused by the application of pressure. Piezometers of the second type are not used in the study of liquids with high viscosity or of solids. In working with such piezometers, p is measured and each change in M is determined either by weighing or, after removal of the load, by such methods as measuring the volume of the discharged gas under standard conditions.

Plunger- or piston-type piezometers are used for determining the compressibility of liquids and solids at pressures in the high range of 108-1010 newtons per square meter (N/m2). During the process of compression, the volume V is determined by noting, either optically or with the aid of electric sensors mounted inside the vessel, the piston’s displacement; a value for ρ is arrived at by measuring the force applied to the piston or by resorting to electric sensors. In a number of cases, the substance under investigation itself serves as a pressure-transmitting medium. For the pressure range ρ ≳ 109-1010 N/m2 (10–100 kilobars), compressibility is determined by other methods, such as X-ray structural analysis. The change in the linear dimensions of bodies acted upon by hydrostatic pressure is measured by linear piezometers.

The term “piezometer” was introduced during the 1820’s in connection with the work done by the British physicist J. Perkins and by H. C. Oersted on the compressibility of liquids. At that time, the piezometer was a vessel that contained the liquid to be investigated. The open end of this vessel was immersed in mercury, which in turn was located at the bottom of a high-pressure vessel. If pressure was applied above the mercury by, for example, water or oil, the mercury would be displaced into the vessel containing the liquid under investigation. The height of the mercury’s rise, which depended both on the applied pressure and the compressibility of the liquid being studied, was recorded visually (in glass piezometers) and by using such means as measuring the resistance change in a platinum wire. Further development of piezometers during the 19th century is associated with the Russian scientists G. F. Parrot, E. Kh. Lents (H. F. E. Lenz), and D. I. Mendeleev and the French physicists E. Amagat and H. V. Regnault; in the 20th century major contributions were made by G. Tammann and the American physicists T. Richards and P. Bridgman.

In the technology of physical experiments at high pressures, the term “piezometer” sometimes denotes thick-walled, high-pressure vessels with a cylindrical channel that are not designed for measurements of compressibility. In English reference sources, the term is also applied to devices used to measure pressures found in flow systems, in the bore of artillery pieces, and at ocean depths.

REFERENCES

Bridgman, P. W. Fizika vysokikh davlenii. Moscow-Leningrad, 1935. (Translated from English.)
Bridgman, P. W. Noveishie raboty v oblasti vysokikh davlenii. Moscow, 1948. (Translated from English.)
Tsiklis, D. S. Tekhnika fiziko-khimicheskikh issledovanii pri vysokikh i sverkhvysokikh davleniiakh, 3rd ed. Moscow, 1965.
Kornfel’d, M. “Metody i rezul’taty issledovaniia ob”emnoi uprugosti veshchestva.” Uspekhifizicheskikh nauk, 1954, vol. 54, issue 2.

L. D. LIVSHITS

piezometer

A device for measuring liquid pressure; used to measure the pore water pressure in soil.
References in periodicals archive ?
Groundwater was collected from the piezometers by manual pumping, and surface water was sampled directly from the channel.
Repetitive detections of human fecal markers occurred at piezometer locations 4 and 5 (Figure 1), which were within the drainfield and <15 m from the septic tank, respectively.
Finally, in this research, along the research period, with increasing of irrigations and decreasing of irrigation frequencies, it was caused the increase in piezometic head in entire piezometers except piezometer A that had not water along the research period.
7%, while based on pneumatic piezometers reading was 56.
Dosing solution was injected between 1100 and 1200 hours, into the piezometer of each lysimeter at the rate of 250 mL/min using a peristaltic pump.
Although both deep and shallow piezometer records clearly show this relationship, only the deep hydrograph data are used for our discussion.
At one site, no differences were found between using suction lysimeters and piezometers for sampling.
By considering all existent Piezometer in Khanmirza aquifer the average groundwater level is dropped approximately 22 meters.
Groundwater flow direction and the orientation of the septic plumes were estimated using electrical resistivity surveying and three-point contouring, with some data from exploratory groundwater piezometers (Heath, 1998; Humphrey, Deal, O'Driscoll, & Lindbo, 2010).
Piezometers were installed in wells formed using a hydraulically driven soil corer.
Septic tanks were sampled monthly from October 2009 to May 2010, and groundwater samples from piezometers and surface water samples from the estuary were collected bimonthly from November 2009 to May 2010.
Figure (8) observe draw curve of velocity of water level fluctuation in reservoir (X-axes) and velocity of water level fluctuation in one piezometer (EP5-2 as an example) (Y-axes).