KR20020088885A - Pressure calibration system and method through deadweight tester - Google Patents

Abstract

PURPOSE: A system and method for calibrating pressure gauge is provided to achieve improved user convenience and reduced error, while shortening time taken for obtaining calibration records and result by permitting the process for making calibration records to be automatically performed. CONSTITUTION: A pressure gauge calibration method, comprises a first step(S110) of inputting initial parameters including information on a standard and an object for calibration and calibration range; a second step(S120) of inputting other parameters required for calibration; a third step(S130,S140) of calculating standard weight list to be used in a pressure calibration range; a fourth step(S150,S160) of selecting one from a deadweight type calibration or a non-deadweight type calibration; a fifth step(S170) of automatically calculating parameters required for deadweight type calibration when the deadweight type calibration is selected and additional parameters are input; a sixth step(S180) of calculating relation between the pressure value of standard and output value of an object for calibration by analyzing all information, and calculating uncertainty; and a seventh step(S190) of outputting calibration records and result in accordance with the uncertainty calculated in the sixth step.

Description

Pressure calibration system and method through deadweight tester

The present invention relates to a pressure gauge calibration system and a calibration method using a deadweight pressure standard, and more particularly, to obtain a correlation between the pressure value of the standard machine and the output value of the calibrator, and automatically calculates the uncertainty calculation, calibration report, etc. The present invention relates to a pressure gauge calibration system and a calibration method using an output deadweight tester.

In general, pressure gauges used for pressure measurement in industrial sites and research institutes include an indicative elastic pressure gauge, a pressure transducer, and a digital pressure gauge. Such pressure gauges may change naturally depending on the characteristics of the device when used for a long time. Because of this, it is necessary to calibrate periodically to measure the correct pressure.

When calibrating pressure gauges, a deadweight pressure standard is usually used to measure the correct pressure.

The deadweight pressure standard can measure the exact pressure, but there are many variables to get the pressure, which are the dead weight, gravity acceleration, air density, dead weight, effective area of the standard, pressure coefficient, piston-cylinder The coefficient of thermal expansion, the difference from the reference temperature, the surface tension coefficient, the circumference of the piston, the fluid density, and the like, and the above variables are substituted into the equation to calculate the pressure.

In addition, in the comparative calibration for calibrating another deadweight tester with a deadweight tester, variables such as atmospheric pressure, relative humidity, and microweight weight are included in addition to the parameters listed above to obtain pressure in a more complicated manner.

In addition, the uncertainty should be calculated when preparing the calibration report, and calculating the uncertainty requires a great deal of attention because it involves many complicated formulas.

As described above, since pressure calibration using a deadweight pressure standard is very complicated, trained calibration performers of many domestic calibration institutes are also having difficulty in calculating pressure calibration, uncertainty calculation, and calibration reports using deadweight pressure standards.

In addition, as described above, apparatuses and methods for automatically performing pressure calibration using a deadweight pressure standard have been developed, but these apparatuses and methods can calculate only the pressure values necessary for pressure calibration and calculate the uncertainty required for the actual pressure calibration. And there is a problem that can not automatically create a calibration certificate.

In particular, there is a problem that can not be calibrated deadweight pressure gauge by comparison calibration using a deadweight pressure standard.

The present invention has been made in view of the above-described problems, the purpose of which is easy for the user to use, the pressure calibration of various types of calibrator using a deadweight pressure standard, the comparison of deadweight pressure calibrator It is intended to provide a convenient user interface for performing calibrations and automatically outputting uncertainty calculations and calibration reports.

1 is a block diagram showing a pressure gauge calibration system using a deadweight pressure standard according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the calibration means shown in FIG.

3 is a flow chart illustrating a pressure gauge calibration method using a deadweight pressure standard according to an embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

10: correction means 11: nitrogen tank

12: pressure regulator 13: pressure standard

14: first reference sensor 15: the first laser distance measuring instrument

16: Calibrator 17: second reference sensor

18: second laser distance measuring instrument 20: control means

30: output means

The configuration of the present invention for achieving the above object is made as follows.

Calibration means for detecting a state of a calibration target to be pressure-calibrated and a pressure standard having a higher accuracy than the calibration unit, and outputting an electrical signal corresponding thereto;

Record and analyze the electrical signal applied by the calibration means to obtain the correlation between the pressure value of the pressure standard and the output value of the calibrator, calculate the uncertainty associated with it, and finally prepare the pressure calibration report to produce the corresponding electrical signal. A control means for outputting;

Characterized in that the output means for outputting the pressure calibration certificate in English / Chinese in accordance with the signal applied from the control means.

Another configuration of the present invention for achieving the above object is made as follows.

Inputting initial variables such as relevant information of the standard, related information of the calibrator, calibration range, main constant, and calibration information;

Additionally inputting an initial variable other than the initial variable inputted according to the selected standard group and the corrector,

Calculating a weight list to be used in the pressure calibration range when the initial variable is input;

Alternatively selecting either a deadweight tester calibration or a non deadweight tester calibration,

When the calibration calibration of deadweight tester is selected and additional variables such as standard temperature, microweight, calibration room temperature, calibration room humidity, and calibration room atmospheric pressure are input again, Automatic calculations,

Calculating the uncertainty associated with the pressure standard pressure and the output of the calibrator by synthesizing / analyzing all the information inputted and calculated above;

And outputting a calibration report and a calibration result according to the uncertainty calculated above.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the present invention will be described in detail.

1 is a block diagram showing a pressure gauge calibration system using a deadweight pressure standard according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the calibration means shown in FIG.

3 is a flow chart illustrating a pressure gauge calibration method using a deadweight pressure standard according to an embodiment of the present invention.

Referring to Figure 1, the pressure gauge calibration system using a standard of the present invention consists of a calibration means 10, a control means 20, and an output means (30).

The calibration means 10 detects a state of the calibrator to be subjected to pressure calibration and a pressure standard having a higher accuracy than the calibrator, and outputs an electrical signal corresponding thereto.

For example, if the corrector and the pressure standard are deadweight gauges, the air temperature, the relative humidity, the atmospheric pressure, the position of the piston-cylinder, and the like are detected and output corresponding electric signals.

As shown in FIG. 2, the calibration means 10 includes a nitrogen tank 11, a pressure regulating device 12, a pressure standard 13, a first reference sensor 14, and a first laser distance meter 15. ), A calibrator 16, a second reference sensor 17, and a second laser range finder 18.

The nitrogen tank 11 is a pressure supply source for supplying each device with the pressure necessary for pressure calibration.

The pressure regulating device 12 properly adjusts the pressure supplied from the nitrogen tank 11 to supply the pressure necessary for the measurement.

The pressure standard 13 adjusts the pressure supplied from the pressure regulating device 12 to a standard pressure and supplies it to the corrector 16.

The pressure standard 13 generally uses a deadweight tester having an accuracy of about four times that of the corrector 16. The deadweight tester places a constant weight on the piston and the piston is lowered by the weight of the weight. Pressure is generated inside the cylinder surrounding the piston, and the pressure inside the cylinder is the pressure of the deadweight tester, and the force exerted by the weight of the weight is divided by the cross-sectional area of the piston.

However, in order to accurately calculate the pressure generated in the cylinder, weight, gravity acceleration, air density, weight density, effective area of the deadweight pressure gauge, pressure coefficient, thermal expansion coefficient of the piston-cylinder, reference temperature, surface tension coefficient, Variables such as piston circumference, fluid density, atmospheric pressure and relative humidity are needed.

The first reference sensor 14 detects variables for calculating the state of the pressure standard 13, that is, the pressure value supplied to the calibrator 16, and outputs corresponding electrical signals to the control means 20. .

The first laser range finder 15 detects a free fall speed of the pressure standard 13 and outputs an electric signal corresponding thereto to the control means 20.

The calibrator 16 is a pressure measuring instrument that is subject to pressure calibration, and outputs its own pressure corresponding to the standard pressure applied by the pressure standard 13.

The corrector 16 may be a pressure gauge used for measuring pressure in an industrial site or a laboratory, that is, various types of pressure gauges such as an indicator elastic pressure gauge, a pressure transducer, a digital pressure gauge, and the like.

The second reference sensor 17 detects variables for calculating the state of the corrector 16, that is, the output value of the corrector 16, and outputs corresponding electrical signals to the control means 20.

If the object of the corrector 16 is a deadweight tester, the second laser range finder 18 detects a free fall speed of the corrector 16 and outputs a corresponding electrical signal to the control means 20.

The control means 20 records and analyzes an electrical signal applied from the calibration means 10 to obtain a correlation between the pressure value of the pressure standard 13 and the output value of the calibrator 14, and calculates an uncertainty associated therewith. Finally, the pressure calibration report is prepared and the corresponding electrical signal is output to the output means 30.

The output means 30 prints the pressure calibration certificate in English / Chinese according to the signal applied from the control means 20.

When the pressure gauge calibration method using the deadweight type pressure standard of the present invention made as described above as shown in FIG.

Referring to FIG. 3, the calibrator first sets initial variables such as related information, calibration range, main constant and calibration information about the pressure standard 13 and the calibrator 16 of the calibration means 10 as shown in [Table 1]. Input it and save it as a file (step 110).

Table 1

object Type of information Standard equipment related information 1.Type of standard machine, product name, manufacturer, model name, equipment number, uncertainty 2.Type of piston, effective area, thermal expansion coefficient, pressure coefficient, piston Tare value 3.Weight density, weight of each weight, weight name, uncertainty Calibrator related information 1.Type of Calibrator, Part Name, Manufacturer, Model Name, Device Number, Pressure Unit, Liquid Level Calibration range Calibration maximum pressure, calibration minimum pressure, calibration pressure number, pressurized or decompression calibration Main constant Gravity acceleration, air density, oil density, oil surface tension, reference temperature Calibration Information Correction number, requesting institution, date of receipt, date of correction, next calibration date, relative humidity, temperature of correction room, name of correction officer, contact information of correction officer, policy officer's name,

Thereafter, the pressure standard 13 for outputting the standard pressure and the calibrator 16 to be calibrated are selected, and then additionally input initial variables such as [Table 2] according to the type of the calibrator 16. (Step 120).

[Table 2]

Type of Calibrator Type of information Deadweight tester 1.Effective cross section, thermal expansion coefficient, weight density, weight of mass, weight name, mass uncertainty, piston tare value Non deadweight tester 1.Maximum pressure, minimum pressure, output type, maximum output, minimum output, minimum scale of the calibrator

The control means 30 then determines whether the calibrator has selected to find the weight list to be used for pressure calibration (step 130).

If it is determined in step 130 that the calibrator has selected to find the weight list to be used for pressure calibration, the control means 20 automatically calculates the weight list to be used in the pressure calibration range (step 140).

Thereafter, the control means 20 determines whether the calibrator has alternatively selected one of the deadweight tester comparison calibration or the non deadweight tester calibration (step 150).

In step 150, when the calibrator selects the calibration calibration of the deadweight tester and inputs initial variables necessary for the calibration of the deadweight tester, that is, the temperature of the standard, the microweight mass, the calibration room temperature, the calibration room humidity, and the calibration room atmospheric pressure 160, the control means 20 analyzes signals output from the first and second reference sensors 14 and 17 and the first and second laser range finders 15 and 18 of the calibration means 10, and then According to the existing program, the variables as shown in [Table 3] are automatically calculated (step 170).

Table 3

Automatically calculated variable Calibration of deadweight tester Weight of standard weight, standard pressure value, weight of corrector weight, effective area of calibrator, average effective area of calibrator, effective area uncertainty, pressure coefficient, standard deviation of pressure coefficient, target pressure, weight of mass, nominal pressure, actual pressure , Correction, extended uncertainty, confidence level, inclusion factor, degrees of freedom

Subsequently, the control means 20 calculates the correlation between the pressure value of the deadweight tester, which is the target of the pressure standard 13, and the output value of the deadweight tester, which is the target of the corrector, by combining / analyzing all the above information. The uncertainty is calculated (step 180).

At this time, by using the uncertainty calculated above, the calibration report and the calibration result are output on the screen, the calibration report and the calibration result, which are corrected by the calibrator after reviewing the corrected matters, and finally, the control means 20. The calibration report and the calibration results are printed in Korean or English using the output means 30 connected to the step (step 150).

However, in step 150, the calibrator does not select the calibration of the deadweight tester, selects the calibration of the non-weighted pressure gauge, and the initial variables necessary for the calibration of the non-weighted pressure gauge, that is, the pressure and depressurization readings of the non-weighted pressure gauge, and the room temperature at the start At the end, if the indoor temperature is further input again (step 200), the control means 20 is output from the first and second reference sensors 14 and 17 and the first distance measurer 15 of the calibration means 10. After analyzing the signal, the variables shown in Table 4 are automatically calculated according to the built-in program (step 210).

TABLE 4

Automatically calculated variable When calibrating a non-weight manometer Weight mass, reference pressure, theoretical output, temperature average, maximum instrument error, hysteresis, pressure correction, standard deviation of Y, standard deviation of section, standard deviation of slope, expansion uncertainty, composite standard uncertainty, confidence level, confidence Coefficient, degrees of freedom

Thereafter, after automatically calculating the variable added in the step 210, and returns to the step 180, the control means 20 synthesizes / analyzes all the information as described above to determine the weight of the deadweight tester. Calculate the correlation between the pressure value and the output of the non-weight manometer that is the target of the calibrator, and then calculate the uncertainty of the non-weight manometer.

As described above, in the present invention, if the variable values necessary for the pressure gauge calibration are sequentially input, the uncertainty required when preparing the calibration report is calculated as an accurate value, so that even an unskilled calibrator can prepare a calibration report without errors, and the uncertainty calculated above. According to the calibration report is automatically generated, the time required for preparing the calibration report can be shortened.

In addition, it is possible to calibrate all kinds of pressure measuring instruments used in industrial sites or laboratories by selectively producing uncertainty calculations and calibration reports according to the type of calibrator to be subjected to pressure calibration.

Claims (4)

Calibration means for detecting a state of a calibration target to be pressure-calibrated and a pressure standard having a higher accuracy than the calibration unit, and outputting an electrical signal corresponding thereto; Record and analyze the electrical signal applied by the calibration means to obtain the correlation between the pressure value of the pressure standard and the output value of the calibrator, calculate the uncertainty associated with it, and finally prepare the pressure calibration report to produce the corresponding electrical signal. A control means for outputting; Pressure gauge calibration system using a deadweight pressure standard, characterized in that the output means for outputting a pressure calibration certificate in English / Chinese according to the signal applied from the control means. The method of claim 1, wherein the calibration means is a nitrogen tank as a pressure supply source, a pressure regulating device for adjusting the pressure supplied from the nitrogen tank, a pressure standard for supplying a standard pressure, and a calibrator to be subjected to pressure calibration And a deadweight pressure standard including first and second reference sensors for detecting the state of the pressure standard and the corrector, and first and second laser distance meters for detecting free fall speeds of the pressure standard and the corrector. Manometer calibration system. Inputting initial variables such as relevant information of the standard, related information of the calibrator, calibration range, main constant, and calibration information; Additionally inputting an initial variable other than the initial variable inputted according to the selected standard group and the corrector, Calculating a weight list to be used in the pressure calibration range when the initial variable is input; Alternatively selecting either a deadweight tester calibration or a non deadweight tester calibration, If the calibration calibration of deadweight pressure gauge is selected and additional variables such as standard temperature, microweight, calibration room temperature, calibration practice, and atmospheric pressure of calibration room are input again, Automatic calculations, Calculating the uncertainty associated with the pressure standard pressure and the output of the calibrator by synthesizing / analyzing all the information inputted and calculated above; Pressure gauge calibration method using a deadweight pressure standard, characterized in that for outputting the calibration report and the calibration result in accordance with the uncertainty calculated above, The method of claim 2, wherein a deadweight tester comparison calibration is not selected and non-weighted pressure gauge calibration is selected, and among the variables, additional variables such as the calibrator pressurization / decompression readings, the room temperature at the start, and the room temperature at the end are entered again. A pressure gauge calibration method using a deadweight pressure standard comprising automatically calculating the necessary parameters when calibrating the non-weight gauge.