SU1714374A1 - Method of measuring mass of liquid in reservoir - Google Patents

Abstract

The invention relates to weighing technology and allows to improve the accuracy of determining the mass of the liquid in the tank. The mass is determined by calculating the product of the hydrostatic pressure of the fluid in the tank, the average cross-sectional area of the filled part of the tank, and the reciprocal of the acceleration of free fall of the body. The difference of the method is the installation of several hydrostatic pressure meters on the tank and the use of ^ (n calculating the readings of one of them, the readings of which lie within the limits at which the measurement error is minimal.

Description

This invention relates to a measurement technique.

The purpose of the invention is to improve accuracy.

The measurement of the mass of fluid in the tank is made by calculating the formula

m-p scp

where m is the mass of fluid in the tank;

P is the hydrostatic pressure of the liquid column;

Scp is the average cross-sectional area of the filled part of the tank, as determined from the tank calibration table;

g - acceleration of free fall of the body.

To measure the hydrostatic pressure of a fluid in a tank, several hydrostatic pressure meters (HDIs) are set at the same level,

whose accuracy class satisfies the condition

d Pnq 3 Rd,

where d Pnq is the error of the d-th datum;

BRD - the relative error of the DI is permissible;

9 1.2k;

K - the total number of established datum.

The permissible relative error of d dd Id is determined from the expression

,

Claims (1)

where b m, (5 S, 5 N are the relative measurement errors of the mass, area, and computer system, respectively. 3171437 The relative error d Rd IGD is defined as 1 oR-dRp-, 5 where A -o is the relative level 1 1 Mg m of liquid in the reservoir; H — height of the liquid column in the reservoir; 10 Nm — height of the liquid in the filled reservoir; P — hydrostatic pressure of liquids: 15 PM — hydrostatic pressure of the liquid with a completely filled reservoir; O gn — reduced error; PM ARmax maximum absolute error of the HDI. Measuring range no hydrostatic pressure is limited by the relative liquid level in the reservoir; Yamin l 1, where Amin xfr is the minimum relative liquid level at which you can measure the mass with a limited error of. The first IDD measures the pressure of the liquid in the tank lying in limits of РМ2 PI РМ1 РМ, where PI is the indication of the first ИГД; РМ2 - the lower limit of the fluid pressure, determined from the condition of providing the required accuracy of measurement of the mass of liquid РМ2 AI min РМ. For the second I1 d, the pressure Km2 is maximum, and the measured pressure lies in the limit from РмЗ to Рм2, where Рмз - А2min Рм2 - 1 min Л2 min РМ. Then, any d-th lIHD, which provides the required accuracy for determining the mass of the fluid, measures the fluid pressure within -P-C Pm (g + 1) Pq p mq. q 1,2К, where Pq is the indication of the q-th datum; OQ 44, PMQ maximum pressure p-tog (IGD; PM (q + i) - minimum pressure d-top IGD, equal to the maximum pressure (d + 1) -th IGD p p n p 1 PA | min Ai min minimum relative level measurements of the i-th DI defined Sr., 1, (5 Pni - the reduced error of the i-togs DI ARMax about Pni -. PiMaKc - the absolute maximum linear |) accuracy of the i-Toro IHD.j From this it follows that each subsequent the additional IHD installed in the tank must have a higher sensitivity than the previous one, since each successive LGD is designed for a lower max. The pressure is greater than the previous one. The relative error of pressure measurement by the q-th HDI will be equal to q -i P Almin p (5p A for A varying within ICH - 1 Limine A 11 Amin |.,. The proposed method is equivalent to the reduction of the Reduced error qi IGD is 1 / P AIMMH times in a system with ii one IGD. Since additional IGDs are designed for a lower maximum pressure, they must be protected from excess pressure. Tlkuyu protection can be implemented by connecting the IGD to the tank through the safety valves. For 1 membrane type IGD, membrane safety stops can be provided. If IHDs of one accuracy class are used, i.e. b Pnq b RP. Yamin for all q 1, 2k, then the measurement range of any q-Toro IGD will be limited to: I-min-I Lmin and the relative measurement error will be: bRs, (5Рп which is equivalent to a decrease in IHD error by 1 I Lt times in the system with Formula of measuring the mass of a liquid in a tank, which consists in establishing a hydrostatic pressure meter and measuring this pressure in the tank, and the mass of a fluid is calculated as the product of the hydrostatic pressure, known as the average cross-sectional area As part of the tank and the magnitude of the inverse of the acceleration of the free pad of the body, characterized in that, in order to increase accuracy, additional hydrostatic pressure meters are set on the same level as, the accuracy class of each of the meters is chosen so that its reduced error does not exceed the allowable relative error measuring hydrostatic pressure, and measuring the hydrostatic pressure of the fluid in the tank is made by alternately turning on the gauges, which lie in the range Rm (q + 1) Pq PMq. where Рм (d + 1) is the indication (d + 1) of the meter; Pq - d-meter readout: Р Mq РМ 11 / ii min РМ - hydrostatic pressure of a liquid with a completely filled tank: Lmin - 6 Pi, d Pq - reduced errors, respectively, i-ro and q-ro meters: i 1,2. .. q ... k: k is the total number of hydrostatic pressure meters installed.