RU216500U1 - DENSITY ANALYZER FOR PRECISION DENSITY MEASUREMENTS OF LIQUIDS - Google Patents

Abstract

The utility model relates to control and measuring equipment, namely to means for measuring the density of liquids and means for metrological support of means for measuring the density of liquids. The density analyzer for precision measurements of the density of liquids includes a cylindrical body in the form of an all-metal vessel with two necks located on the same axis, two shut-off valves located on the necks, and a safety pressure relief valve, while the capacity of the cylindrical body has a metrologically optimal capacity of 1450 ± 50 cm ³ , providing the limits of the permissible absolute error in measuring the density of the liquid ± 0.05 kg / m ³ . The utility model makes it possible to reduce the measurement error of liquid density to a value not exceeding 0.05 kg/m ³ . 1 ill.

Description

Field of technology to which the utility model belongs

The utility model relates to control and measuring equipment, namely to means for measuring the density of liquids and means for metrological support of means for measuring the density of liquids.

State of the art

The density analyzer is intended for operation as part of a standard installation for reproducing, storing and transmitting a unit volume of liquid during precision measurements of liquid density in conditions of transportation through process pipelines, as well as for verifying, calibrating and grading density transducers and density measurement channels of mass flow meters in operating and laboratory conditions.

The principle of density measurements using a density analyzer is based on determining the mass of a liquid sample taken into a density analyzer of known capacity at temperature and pressure in the pipeline. The density of a liquid is found as the quotient of the difference between the masses of the filled and empty analyzers divided by the analyzer's capacity under liquid sampling conditions. The pressure, temperature of the liquid and body temperature of the analyzer are determined at the time of sampling the liquid using measuring instruments from the set of the reference installation.

A device for determining the density of a liquid under pressure is known from the prior art, consisting of a cylindrical tank made of several stainless steel parts to be welded, and two shut-off needles located on the same axis (see [1] copyright certificate SU 142798 A1, IPC G01N 9 /02, I. L. Markhasin, I. A. Fakhreev, G. P. Meintzer, published in 1961).

The disadvantage of this device is the impossibility of ensuring the measurement error of the density of the liquid is less than 0.4 kg/m3.

A metal pycnometer is known from the prior art for a density unit standard (see [2] patent RU 205581 U1, IPC G01N9/04, publ. stopcock, which are located coaxially with the pycnometer, and the lower part is additionally equipped with an emergency safety membrane, while the pycnometer is made of stainless steel alloy with titanium.

The disadvantage of this pycnometer is the impossibility of providing an error in measuring the density of a liquid less than 0.1 kg/ ^m errors from ±0.10 kg/ ^m3 to ±0.20 kg/ ^m3 ).

As the closest analogue, taken as a prototype, we accept a metal pycnometer for the density unit standard (see [3] patent RU 206662 U1, IPC G01N 9/04, publ. 09/21/2021), including the upper and lower parts interconnected welded circular seam, each of which is equipped with a shut-off valve, which are located coaxially with the pycnometer, and the lower part is additionally equipped with an emergency safety membrane, while the edges of the upper and lower parts of the pycnometer are made with a stepped bevel for welding.

The disadvantage of the closest analogue is also the impossibility of ensuring the measurement error of the density of the liquid is less than 0.1 kg/m ³ necessary for precision measurements of the density of the liquid, as well as for verification, calibration and calibration of some modern density measuring instruments.

The essence of the utility model

The objective of the claimed utility model is to create a density analyzer for precision measurements of liquid density and metrological support for liquid density measuring instruments with improved metrological characteristics.

The technical result is to reduce the measurement error of the density of the liquid to a value not exceeding 0.05 kg/m ³ .

The problem is solved, and the technical result is achieved by a density analyzer for precision measurements of the density of liquids, including a cylindrical body in the form of an all-metal vessel with two necks located on the same axis, two shut-off valves located on the necks, and a pressure relief valve, while the container of the cylindrical body has a metrologically optimal capacity of 1450±50 cm ³ , which provides the limits of the permissible absolute error in liquid density measurements of ±0.05 kg/m ³ .

Brief description of the drawings

Fig. 1 is a general view of a density analyzer for precision measurements of the density of liquids.

The following positions are indicated on the figure: 1 - housing; 2, 3 - neck; 4, 5 - stopcock; 6 - pressure relief valve.

Implementation of the utility model

The problem is solved, and the technical result is achieved by the claimed density analyzer for precision measurements of the density of liquids. Structurally, the analyzer consists of a cylindrical body (1) in the form of an all-metal vessel with two necks (2, 3) located opposite each other on the same axis. On each neck (2) and (3) there is a stopcock (4) and (5), respectively (see Fig. 1). A safety pressure relief valve (6) is installed on the body (1).

A distinctive feature of the claimed utility model is the metrologically optimal capacity of the cylindrical body 1 of the analyzer, which is 1450±50 cm ³ . It should be noted that the value of ±50 cm ³ is a tolerance for volume values for different density analyzers, which cannot be exactly the same due to the manufacturing technology of these density analyzers.

The use of the declared capacity makes it possible to provide a smaller, in comparison with analogues, measurement error of the liquid density due to the revealed dependence of the density measurement error on the capacity of the analyzer body, determined by the formula:

where Δρ _AP is the absolute error in measuring the density of the liquid by the analyzer, kg/m ³ ;

V _nom - capacity of the body of the analyzer, ^cm3 ;

W _P , W ₃ - the results of weighing an empty and filled analyzer, respectively, g;

ΔМ _Гп , ΔМ _Гз - total absolute error of mass values of sets of weights replacing empty and filled analyzer, respectively, g.

S is the standard deviation of the readings of the weighing device, g;

t _0.95 - quantile of Student's distribution, corresponding to the number of measurements, at which the standard deviation of the readings of the weighing device was determined;

ρ _a - atmospheric air density, g / cm ³ ;

Δρ _a - absolute error in calculating the density of atmospheric air, g/cm ³ ;

ρ _g - weight material density;

Δρ _g - deviation of the density of the material of the weights from the value adopted in the calculations, g/cm ³ ;

K _t - coefficient of change in the capacity of the analyzer when the temperature of the liquid changes, cm ³ /°C;

ΔK _t - error in determining the coefficient of change in the capacity of the analyzer when the temperature of the liquid changes, cm ³ /°C;

K _P - coefficient of change in the capacity of the analyzer with a change in fluid pressure, cm ³ /bar;

ΔK _P - error in determining the coefficient of change in the capacity of the analyzer with a change in fluid pressure, cm ³ /bar;

t is the temperature of the liquid in the analyzer, °С;

Δt - error of the temperature measuring instrument in the analyzer, °C;

P is the liquid pressure in the analyzer, bar;

ΔР - error of the pressure measuring instrument in the analyzer, bar.

The inventive analyzer provides the limits of the permissible absolute error in measuring the density of the liquid ±0.05 kg/m ³ .

The inventive density analyzer for precision measurements of the density of liquids operates as follows:

the density analyzer is operated as part of a standard installation for metrological support of liquid density measuring instruments, which, in addition to one or several density analyzers, also includes temperature and pressure measuring instruments, a weighing device (balances or mass comparator), flow indicator, technological equipment;

before starting measurements, the density analyzer is washed and dried;

weigh the empty density analyzer;

installation for metrological support of measuring instruments for the density of liquids is connected to the pipeline with the analyzed liquid;

open stopcocks 4 and 5;

maintain the time required to stabilize the temperature of the liquid;

shut-off valves 4 and 5 are closed and the temperature and pressure of the analyzed liquid are recorded;

rinse and dry the outside of the density analyzer;

weighing the liquid-filled density analyzer;

determine the density of the liquid as the quotient of dividing the difference between the masses of the filled and empty analyzer by the value of the analyzer capacity under the conditions of sampling the liquid.

Claims (1)

A pycnometer containing a cylindrical body in the form of an all-metal vessel with two necks located on the same axis, two stopcocks located on the necks, and a safety pressure relief valve, characterized in that the capacity of the cylindrical body has a metrologically optimal capacity of 1450±50 cm ³ , providing limits of permissible absolute error in liquid density measurements ±0.05 kg/m ³ .

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