JP2013134180A - Flow rate measuring method and flow rate measuring apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the same flow rate as a flow rate measured by a regulated test pressure without performing test pressure adjustment even when a test pressure actually applied to a work is deviated from the regulated test pressure.SOLUTION: Gas to be supplied to the work through a flowmeter (20) is set to the test pressure by a pressure adjusting valve (12), a flow rate of the gas flowing out from the work in a measurement environment is measured by the flowmeter, gas temperature and atmospheric pressure in the measurement environment are measured, and the flow rate is converted into a flow rate of a reference state by a flow rate conversion part (30R) on the basis of the measured temperature and atmospheric pressure. A flow rate correction part (30C) calculates a correction coefficient for correcting the converted flow rate to a flow rate obtained when the gas of the regulated test pressure is applied to the work on the basis of the regulated test pressure, the measured gas and the actual test pressure and multiplies the converted flow rate by the correction coefficient, and the corrected conversion flow rate is displayed on a display part (31).

Description

  The present invention relates to a flow rate measurement method with little influence of a measurement environment and a flow rate measurement apparatus using the same.

  The flow rate measuring device is used, for example, for flow rate measurement of gas leaking from a container, flow rate measurement or flow rate management for adjusting supply amount of arbitrary gas. In these flow measurement, the gas supply target is hereinafter referred to as a work. In order to measure the flow rate, for example, a test pressure gas is supplied to the work through a flow meter, and the outflow amount of the gas from the work is measured. In the following description, the target gas for flow rate measurement is air, but it can also be applied to other arbitrary gases.

  FIG. 1 shows a conventional example of a flow rate measuring device used for such a gas flow rate measurement. The flow measuring device 230 in FIG. 1 includes a test conduit 14 connected to the pneumatic pressure source 11, a pressure control valve 12 inserted in series with the test conduit 14, and a test conduit 14 inserted in series downstream of the pressure control valve 12. The flow meter 20, the on-off valve 16 inserted in series with the test conduit 14 on the downstream side of the flow meter 20, the test pressure gauge 13 connected to the test conduit 14 on the downstream of the on-off valve 16, and the arithmetic unit 30. The display unit 31 for displaying the flow rate of the calculation result, the thermometer 32 for measuring the atmospheric temperature in the measurement environment, and the barometer 33 for measuring the atmospheric pressure, and the work 40 is connected to the downstream end of the test conduit 14. Is done. The air pressure source 11 may be included in the flow measurement device 230. The air pressure source 11 may generate a positive pressure or a negative pressure. The flow meter 20 may be any type of flow meter such as a differential pressure flow meter, a laminar flow meter, or a hot wire flow meter.

It is considered that the temperature of the gas supplied to the workpiece 40 is the same as the atmospheric temperature. The arithmetic device 30 includes a storage unit 30M and a flow rate conversion unit 30R. The storage unit 30M stores, for example, the standard atmospheric pressure (1013 hPa) and temperature (293K) in advance, and stores the atmospheric pressure of the measurement environment, the measured value of the temperature, and the flow rate measured by the flow meter 20 as necessary. And may be used. The flow rate conversion unit 30R is provided with the measured flow rate Q _t in the measurement environment from the flow meter 20, the temperature t from the thermometer 32, the atmospheric pressure B from the barometer 33, and the coefficient held in the storage unit 30M. The flow rate measured by the flow meter 20 (hereinafter referred to as the flow rate in the measurement environment) Q _t is converted into a flow rate Q ₂₀ ′ in a standard state (for example, 20 ° C., 1 atm (1013 hPa)) on the display unit 31. Give and display.

When the flow velocity is less than the sonic velocity and the leakage hole of the workpiece 40 has an orifice characteristic, the gas outflow from the workpiece 40 follows Bernoulli's theorem, so that a gas having a test pressure ΔP that is a differential pressure with respect to atmospheric pressure is given to the workpiece 40. The flow rate Q _t measured by the flow meter 20 corresponding to the flow rate Q of the gas flowing out from the hole 41 of the workpiece when

It is represented by K is a shape factor determined by the size and shape of the hole 41 of the workpiece, and is a fixed value. Q _t is the actual volume flow rate (mL / min) measured by the flow meter 20 when the test pressure ΔP = P _t is given in the measurement environment (the temperature by the thermometer 32 is t ° C. and the atmospheric pressure by the barometer 33 is BhPa). ). ρ _t is an air density determined by the air pressure (P _t + B) applied to the workpiece and its temperature (hereinafter, assumed to be the same as the environmental temperature t ° C.).

In FIG. 1, after the work 40 is attached to the test conduit 14, the on-off valve 16 is opened, and the gas from the pneumatic source 11 is supplied to the work 40 through the flow meter 20. The pressure regulating valve 12 is adjusted and set so that a differential pressure ΔP (also referred to as gauge pressure) with respect to the atmospheric pressure B of the gas supplied to the workpiece 40 displayed on the test pressure gauge 13 becomes a prescribed test pressure. At this time, the actual volume flow rate Q _t corresponding to the flow rate Q of the gas flowing out from the workpiece 40 is measured by the flow meter 20.

Thus, the measured flow rate Q _t represented by the equation (1) is the actual volume flow rate in the environment at the temperature t and the atmospheric pressure B (hPa), and if at least one of the temperature and the atmospheric pressure changes, the equation (1) In this case, since the air density ρ _t changes, the measured flow rate Q _t changes even with the same workpiece 40. That is, since the environmental conditions (atmospheric pressure B and temperature t in the measurement environment) change if the time at which the flow measuring device is used or the time at the same place changes, the flow rate Q _t measured using the same flow meter 20. Has the disadvantage of showing different values.

By measuring the flow rate Q _t by the flow meter 20, for example, in the inspected work, whether gas outflow amount is smaller than the reference value or, alternatively requested work good by determining large or not than a reference value from the work If it is determined whether the product is defective or not, the determination result is affected by the environment. For example, when judging the quality of a workpiece based on the size of the workpiece leakage, if it can be measured as a flow rate that depends only on the size of the hole in the workpiece (for example, the diameter or area of the hole) that is the cause of the leakage, Although it is possible to obtain a quality judgment result that does not depend on the environment, even if the hole size is the same, it is actually affected by the measurement environment.

  Alternatively, when the flow rate measuring device 230 is calibrated by connecting a flow rate resistance setting nozzle (see, for example, Patent Document 1) that generates a specified flow rate for a specified test pressure in the standard state instead of the workpiece 40, the flow rate resistance is inherent Although it is desired that the flow rate can be calibrated only depending on the hole diameter of the setting nozzle, the flow rate varies depending on the measurement environment.

Therefore, conventionally, in the inspection of the leakage amount of the workpiece, the actual volume flow rate Q _t corresponding to the leakage amount from the workpiece is measured by the flow meter 20, and the actual volume flow rate Q _t is determined in advance by the flow rate conversion unit 30R of the arithmetic unit 30. It is converted into a standard state, for example, a flow rate Q ₍₂₀₎ at 20 ° C. and 1 atm (1013 hPa) and converted and displayed using Boyle-Charles' law. Specifically, considering the actual volumetric flow rate Q _t of the test pressure P _t and the mass flow of [rho _t Q _t, is equal and converted mass flow ρ ₂₀ Q ₍₂₀₎ in the standard state, the following equation

Is converted and displayed on the display unit 31. Hereinafter, R is referred to as a conversion factor. The value of the conversion factor R is uniquely determined if the gas temperature t, the atmospheric pressure B, and the test pressure P _{t in the} measurement environment are determined. Q ₍₂₀₎ is the converted volumetric flow rate in the standard state, and ρ ₂₀ is the density of air in the standard state. As the standard state, for example, a temperature of 0 ° C. and an atmospheric pressure of 1013 hPa may be used, but in the following explanation, the temperature is 20 ° C. and the atmospheric pressure is 1013 hPa. Such conversion to the flow rate in the standard state is the same as the flow rate conversion using the Boyle-Charles law shown in Patent Document 2, for example.

Japanese Patent No. 3778359 JP 11-190653 A

  In the flow rate inspection apparatus of FIG. 1, it is necessary to adjust the pressure regulating valve 12 to set the test pressure for the workpiece 40 displayed on the test pressure gauge 13 to a specified test pressure. In reality, the environmental temperature and atmospheric pressure change as a large number of workpieces are inspected sequentially, and it is necessary to adjust the test pressure each time the actual test pressure deviates from the specified test pressure by a predetermined value or more. It was. In addition, the amount of leakage is usually different for each workpiece, and the flow rate changes each time the workpiece is replaced. As a result, the test pressure applied to the workpiece changes, so that the test pressure is adjusted to the specified test pressure by the pressure regulating valve 12. It needs to be adjusted. If such adjustment is performed manually with the pressure regulating valve 12 in a short time, the error of the set test pressure with respect to the specified test pressure increases, and if the error is reduced, there is an inconvenience that each setting takes time. .

  Therefore, as shown by a broken line in FIG. 1, the measurement result of the test pressure gauge 13 is given to the feedback control unit 50 as an electric signal, and the pressure regulating valve 12 is set by the feedback control unit 50 so that the measured test pressure becomes a specified set test pressure. Automatic adjustment is done. However, such an automatic control mechanism has a problem that the price is high, the delay of the feedback loop is large, and it takes time for the set test pressure hunting to converge.

  The object of the present invention is that, without using an expensive feedback control mechanism, even if the actual test pressure applied to the workpiece deviates from the specified test pressure, the flow rate is measured at the specified test pressure without adjusting the test pressure. To provide a flow rate measuring method and a flow rate measuring device that can obtain the same result.

According to the first aspect of the present invention, the atmospheric pressure B and temperature t _ac of the measurement environment are measured, the test pressure P _{ac of the} gas supplied to the work through the flow meter is measured, and the actual volume in the measurement environment by the flow meter is measured. the flow rate Q _ac measured, in the standard state by multiplying a conversion factor to a predetermined standard state determined by the temperature t _ac and the pressure B and the test pressure P _ac the actual volumetric flow rate Q _ac in the measurement environment in terms of the flow rate Q _{ac (20),} the predetermined prescribed test pressure P _p and measured the pressure B and the test pressure P _ac, the conversion rate Q _{ac (20),} defined above test pressure P _p A correction coefficient for correcting the flow rate when the gas is applied to the work is calculated, and the correction flow rate Q _{ac (20)} is multiplied by the correction coefficient to correct when the specified test pressure P _p is applied to the work. The obtained converted flow rate Q _{p (20)} is obtained and displayed.

The second flow measurement method according to the present invention measures the atmospheric pressure B and temperature t _ac of the measurement environment, measures the test pressure P _{ac of the} gas supplied to the work through the flow meter, and measures the actual volume in the measurement environment by the flow meter. the flow rate Q _ac measured, in the standard state by multiplying a conversion factor to a predetermined standard state determined by the temperature t _ac and the pressure B and the test pressure P _ac the actual volumetric flow rate Q _ac in the measurement environment in terms of conversion rate Q _{ac (20),} the predetermined prescribed test pressure P _p and measured the pressure B and the test pressure P _ac, the terms flow Q _{ac (20),} defined above test pressure of the gas Is equivalent to the flow rate equivalent to that applied to the workpiece in the standard condition, and the above specified test pressure P _p is applied to the workpiece in the standard condition by multiplying the equivalent flow rate Q _{ac (20)} by the equivalent factor. It is characterized by obtaining and displaying the equivalent flow rate Q _Ep when

  In the present invention, even if the test pressure of the gas actually supplied to the workpiece deviates from the specified test pressure, almost the same flow rate measurement result as that measured at the specified test pressure can be obtained.

The block diagram of the conventional flow volume inspection apparatus is shown. A shows a schematic diagram when the leakage characteristic of the workpiece is an orifice, and B shows a schematic diagram when the leakage characteristic of the workpiece is a thin tube. The block diagram which shows 1st Example of the flow measuring device by this invention. The flowchart which shows the process of the flow measuring method by 1st Example. The flow which shows the process of the flow measurement corresponding to a different leak characteristic is shown. The block diagram which shows the modification of 1st Example. A is a table showing a comparison of measured flow rates when the test pressure according to the prior art of the first workpiece and the first embodiment is changed, and B is a graph thereof. A is a table showing a comparison of measured flow rates when the test pressure according to the conventional technique of the second workpiece and the first embodiment is changed, and B is a graph thereof. A is a table showing a comparison of measured flow rates when the test pressure according to the third prior art and the first embodiment is changed, and B is a graph thereof. The block diagram which shows 2nd Example of the flow measuring device by this invention. The flowchart which shows the process of the flow measuring method by 2nd Example.

  According to the present invention, when the test pressure deviates from the specified test pressure, the flow rate at the specified test pressure is obtained by calculation from the measured flow rate at that time.

[Introduction to the flow measurement principle of the present invention]
The calculation formula for pressure fluctuation correction differs depending on the flow velocity of the gas flowing through the workpiece and the leakage characteristics of the workpiece. Here, the following three states are considered.
(1) When the flow velocity is less than the speed of sound at a workpiece leakage hole with orifice characteristics.
(2) When the flow velocity is sonic at the orifice hole of the workpiece with orifice characteristics.
(3) When the leakage characteristics of the work causes a viscous flow.

[When the leakage characteristic of the workpiece is an orifice characteristic less than the speed of sound]
As schematically shown in FIG. 2A, assuming that the hole of the workpiece is an orifice, the gas pressure at the inlet of the orifice is P ₁ (gauge pressure), and the pressure at the outlet is P ₀ (gauge pressure). As is well known, the flow rate Q _t on the inlet side is expressed by the following equation when the flow velocity is less than the sonic velocity.

Since the outlet of the orifice is open to the atmosphere, P ₀ is atmospheric pressure. The differential pressure between the inlet and outlet (orifice differential pressure) is ΔP = P ₁ −P ₀ , and ρ is the gas density when the pressure of the applied gas is P ₁ + P ₀ and the temperature is t. The pressure P ₁ corresponds to the test pressure. The gauge pressure represents a differential pressure from the atmospheric pressure P _0, and thus P ₀ = 0 and ΔP = P ₁ .

In FIG. 2A, if the test pressure actually applied to the workpiece is P _ac (gauge pressure), the orifice differential pressure is ΔP _ac = P _ac , and the flow rate Q _ac at the orifice inlet at that time is given by the following equation. .

However, if the atmospheric pressure at the time of measurement is B (hPa), ρ _ac is a gas density at a pressure P _ac + B (absolute pressure) and a temperature t ° C.

Similarly, in FIG. 2A, the flow rate Q _p when a prescribed test pressure P _p is applied to the workpiece is given by the following equation.

However, ρ _p represents the gas density at pressure P _p + B and temperature t.

  From the equations (4) and (5), the following equation is obtained.

Since the density ρ is expressed by W (mass) / V (volume), the gas density ρ _ac of the test pressure P _{ac in} the measurement environment (atmospheric pressure B, temperature t ° C.) and the specified test pressure P in the same environment The ratio of the density ρ _p of the gas _p is ρ _ac / ρ _p = V _p (volume at the specified test pressure Pa) / V _ac (volume at the test pressure P _ac ). When the relationship between the volume V _ac and V _p is expressed by Boyle Charles' law,

Therefore, the density ratio is expressed by the following equation.

Using this density ratio, the following equation is obtained from equation (6).

Is measured in real when the test pressure P _ac deviates from prescribed test pressure P _p, actual volume measured at actual test pressure P _ac flow Q _ac the prescribed test pressure P _p Equation (8) The relationship between the actual volume flow rate Q _p is shown. However, this relational expression is a relational expression in the measurement environment (temperature t, atmospheric pressure B), and in a generally used flow measurement device, the flow rate is in a standard state (for example, 20 ° C. = 273 K, 1 atmospheric pressure = 10 13 hPa). It is normal to display in terms of flow rate. The conversion formula is derived below.

When the actual volume flow rate Q _ac measured at the test pressure P _ac in the environment of temperature t _ac and atmospheric pressure B is converted to the converted flow rate P _{ac (20)} in the standard state (20 ° C, 1013 hPa), it is expressed by the following equation. .

R ₁ is a conversion factor, which is substantially the same as the conversion factor R in equation (2). From equation (9), the flow rate Q _ac is

It becomes. Similarly, the converted flow rate Q _{p (20)} at the specified test pressure P _p at the temperature t _ac is

Given in. When equations (10) and (11) are put into equation (8), the following equation is obtained.

Equation (12), the actual test pressure to standard conditions of actual volume flow rate Q _ac of gas leaking below sound velocity at the time of P _ac conversion rate Q _{ac (20),} a work gas prescribed test pressure P _p This is a pressure fluctuation correction formula that corrects the measured flow rate Q _p to the converted flow rate Q _{p (20)} to the standard state when it is assumed that the measured flow rate Q _p is supplied and measured. That is, the specified test pressure P _p is determined, but the flow rate Q _ac is measured by the actually applied test pressure P _ac that deviates from the specified test pressure in the measurement environment (atmospheric pressure B, temperature t _ac ° C). If the converted flow rate Q ₍₂₀₎ is obtained from the formula (2) according to the conventional method, the flow rate Q _p measured at the specified test pressure P _p is multiplied by the correction coefficient C ₁ as shown in the formula (12). This means that the converted flow rate Q _{p (20)} in the standard state is obtained.

[When workpiece leakage characteristics are sonic orifice characteristics]
In FIG. 2A, when the absolute pressure ratio between the pressure P ₁ at the inlet of the orifice and the pressure P _{0 at} the outlet becomes 1.89 or more, that is, (B + P ₁ ) / (B + P ₀ ) ≧ 1.89, the orifice passes. The flow velocity of the gas is sonic and does not exceed the sonic velocity. The characteristic equation of the orifice at this time is expressed by the following equation.

Q _t = K _L1 × (B + P ₁ ) (13)
In the flow rate measurement at this time, consider the case where the test pressure deviates from the specified test pressure.

_Assuming that a test pressure P _ac deviating from the specified test pressure P _p is given to the inlet of the orifice, the actual volume flow rate Q _ac at the inlet at that time is calculated from the equation (13).
Q _ac = K _L1 × (B + P _ac ) (14)
It is expressed. Similarly, the actual volume flow rate Q _p when a specified test pressure P _p is applied to the inlet of the orifice is obtained from equation (13).
Q _p = K _L1 × (B + P _p ) (15)
It is expressed. From equations (14) and (15)

From equation (15), the flow rate Q _p is given by the following equation.

Pressure (B + P _ac), in terms of the flow rate Q _{ac (20)} the actual volumetric flow rate at the temperature t _ac is converted into a flow rate of Q _ac under standard conditions (1013 hPa, 20 ° C.), the

It becomes. Expression (18) is the same as Expression (9), and the conversion coefficient R ₂ is the same as the conversion coefficient R ₁ . By transforming equation (18)

Is obtained. Similarly, the converted flow rate Q _{p (20)} at the specified test pressure P _p is expressed by the following equation.

Substituting equations (19) and (20) into equation (17),

Is obtained as a pressure fluctuation correction formula at the converted flow rate of the orifice characteristic at the speed of sound. Again, even if misalignment actual test pressure P _ac from prescribed test pressure P _p, in terms of the flow rate Q _{ac (20)} to the correction by multiplying the coefficient C ₂ of the flow rate measured at specified test pressure P _p The converted flow rate Q _{p (20)} to the standard state can be obtained.

[When work leakage characteristics are viscous flow]
As schematically shown in FIG. 2B, when the leak hole of the workpiece is regarded as a narrow tube, the flow rate of the gas flowing through the narrow tube is affected by the viscosity. In such a case, the Hagen-Poiseuille equation, which is a viscous flow equation, is followed. The basic formula is expressed as follows.

Q ′ _t is the flow rate of the gas flowing in the narrow tube, K _L2 is the shape factor of the hole that generates the viscous flow, η is the fluid viscosity at the time of measurement, ΔP is the test pressure P ₁ and the atmospheric pressure P ₀ The difference is P ₁ -P ₀ . Atmospheric pressure is gauge pressure and P ₀ = 0, so ΔP = P ₁ . In FIG. 2B, _assuming that a test pressure P _ac deviating from the specified test pressure P _p is applied to the workpiece in the measurement environment of the temperature t _ac ° C. and the atmospheric pressure B (hPa), the actual volume flow rate Q flowing through the narrow tube at that time ' _ac from equation (22)

It becomes. In addition, the actual volume flow rate Q ′ _p flowing through the narrow tube when the specified test pressure P _p is applied in the same measurement environment is similarly obtained from the equation (22).

It becomes. From equations (23) and (24)

Is obtained. In the case of a viscous flow, an almost constant pressure loss occurs per unit length of the narrow tube, so that the gas pressure in the narrow tube can be regarded as an average pressure (P ₁ -P ₀ ) / 2. Converting the actual volume flow rate Q ' _ac flowing through the narrow tube in the measurement environment of temperature t _ac ° C and pressure B to the flow rate Q _{ac (20)} in the standard state (1 atm, 20 ° C),

It becomes. R ₃ is a conversion factor. If equation (26) is transformed

It becomes. Similarly, when a specified test pressure P _p is applied in the same measurement environment, an equation for converting the actual volume flow rate Q ′ _p flowing through the narrow tube into the flow rate Q _{p (20)} in the standard state is obtained and transformed,

Is obtained. Substituting Q ′ _ac and Q ′ _p in equations (27) and (28) into equation (25) yields the following equation.

Expression (29) represents a pressure fluctuation correction expression with respect to the converted flow rate in the case of the workpiece leakage characteristic of the viscous flow. That is, the flow rate measured at the specified test pressure P _p is converted into the standard flow rate by multiplying the flow rate measured at the test pressure P _ac into the standard flow rate Q _{ac (20)} by the correction coefficient C _3. Q _{p (20)} is obtained. However, in the equation (26) that gives the converted flow rate Q _{ac (20} ) in the equation (29), the flow rate Q ′ _ac is the flow rate in the narrow tube and cannot be directly measured. Therefore, when the flow rate Q ′ _ac in the narrow tube is converted into the flow rate Q _ac at the inlet of the narrow tube,

Therefore, substituting Q ′ _ac in equation (30) into equation (26) yields the following equation.

The conversion factor R ′ ₃ is the same as the conversion factors R ₁ and R ₂ . Therefore, the converted flow rate Q _{ac (20} ) in the equation (29) may be calculated from the equation (31) using the measured flow rate Q _ac .

[First embodiment]
In the above description, the converted flow rate Q _{ac (20)} measured at the test pressure P _ac deviated from the specified test pressure P _p for each of the three workpiece leakage characteristics is converted into the converted flow rate Q when measured at the specified test pressure P _{p. The} formula to convert to _{p (20)} is shown. In this first embodiment, a flow rate measuring device capable of correcting pressure fluctuations when the flow velocity is less than the sonic velocity and the workpiece leakage characteristic will be described first. The modification which enables the pressure fluctuation correction in the case of the leak characteristic will be described.

  Hereinafter, a flow rate measuring device and a measuring method when the flow velocity is lower than the sound velocity will be described with reference to FIG.

FIG. 3 shows a first embodiment of a flow rate measuring apparatus using a flow meter as in FIG. 1, and FIG. 4 shows a flowchart of the measuring method. A difference from the flow rate measurement device 230 in FIG. 1 is that a calculation device 30 ′ in which a flow rate correction unit 30C is added to the calculation device 30 in FIG. 1 is used. Other configurations are the same as those in FIG. Accordingly, the processing of the flow rate correction unit 30C is newly added to the conventional arithmetic unit 30, and the rest is the same as FIG. The flow rate conversion unit 30R calculates the converted flow rate Q _{ac (20)} according to the formula (9), (18), or (31) according to the selection by the selection unit 34. Flow rate correction unit 30C calculates the correction coefficient C ₃ of the correction factor C ₂ or formula for correction factor C ₁ or of formula (12a) in response to the selection by the selection section 34 (21a) (29a), further wherein (12 ) Or (21) or (29), the corrected conversion flow rate (that is, the conversion flow rate when the specified test pressure is supplied) Q _{p (20)} is calculated.

  Hereinafter, the measurement procedure will be described.

First, the work 40 is attached to the downstream end of the test conduit 14 with the on-off valve 16 closed.
Step S1: The on-off valve 16 is opened, gas is supplied from the air pressure source 11 to the work 40 through the flow meter 20, the pressure regulating valve 12 is adjusted, and the gauge pressure (differential pressure ΔP from the atmospheric pressure) indicated by the test pressure gauge 13 is obtained. The test pressure P _ac is set so as to be within a predetermined allowable range with _respect to the specified test pressure P _p .
Step S2: _Read the atmospheric temperature t _ac (° C.) and atmospheric pressure B (hPa) of the measurement environment from the thermometer 32 and the barometer 33 into the storage unit 30M.
Step S3: The actual volume flow rate Q _ac in the measurement environment measured by the flow meter 20 is taken into the arithmetic unit 30 ′.
Step S4: The flow rate conversion unit 30R calculates the converted flow rate Q _{ac (20)} with _respect to the actual volume flow rate Q _ac in the measurement environment using the air pressure B, the temperature t _ac and the test pressure P _{ac according} to the equation (9).
Step S5: In the flow correction unit 30C, measured atmospheric pressure B, the measured test pressure P _ac, with a prescribed test pressure P _p to calculate the correction coefficient C ₁ by the equation (12a), in terms of flow by further equation (12) Q _{ac (20)} is multiplied by the correction coefficient C ₁ to obtain a converted flow rate Q _{p (20) of the} flow rate to the standard state by the specified test pressure P _p and displayed on the display unit 31.

What is necessary is just to perform said step S1-S5 whenever a workpiece | work is replaced | exchanged. The test pressure in step S1 may be set with an error within a predetermined allowable range with _respect to the specified test pressure P _p , and the allowable range may be as large as about ± 10% of the specified test pressure, as will be described later. Because it is good, the time required for setting is short. Even if the set test pressure fluctuates, the correct conversion flow rate obtained by converting the flow rate measured at the specified test pressure into the standard state can always be obtained by the correction according to the equation (12).

  In the above description, the flow rate measurement with the workpiece leakage characteristic less than the sonic speed has been described. However, as shown in the flowchart in FIG. 5 as a modified example, the flow rate when the workpiece leakage characteristic is less than the sonic velocity, It is also possible to make it possible to measure by distinguishing the flow rate in the case of making them.

As shown by a broken line in FIG. 3, a selection unit 34 is provided, and an operator designates whether the workpiece generates a viscous flow or an orifice characteristic by the selection unit.
Steps S1 to S3 in FIG. 5 are the same as steps S1 to S3 in FIG.
Step SX1: It is determined whether the leakage characteristic of the workpiece set by the selection unit is a viscous flow characteristic or an orifice characteristic. If the characteristic is a viscous flow characteristic, the process proceeds to Step S43. If the characteristic is an orifice characteristic, the process proceeds to Step SX2.
Step SX2: Determine whether (B + P _ac ) is 1.89 × B or more from the set test pressure P _ac (gauge pressure) and the measured atmospheric pressure B (hPa). If yes, the process proceeds to step S41, and if yes, the flow velocity is the speed of sound, and the process proceeds to step S42.
Steps S41 and S51 are the same as steps S4 and S5 in FIG.
Step S42: Since the flow velocity is the sonic velocity, the flow rate measured at the test pressure P _ac in the measurement environment is converted into the flow rate Q _{ac (20)} in the standard state using Equation (18).
Step S52: Multiplying the converted flow rate Q _{ac (20)} by the correction coefficient C _{2 according} to the equation (21 ₎ to obtain the converted flow rate Q _{p (20)} to the standard state of the flow rate by the specified test pressure, and displaying it.
Step S43: This is a case where the leakage characteristic of the workpiece is a viscous flow, and the flow rate measured at the test pressure P _ac in the measurement environment is converted into the flow rate Q _{ac (20)} in the standard state by the equation (31).
Step S53: Multiplying the converted flow rate Q _{ac (20)} by the correction coefficient C _{3 according} to the equation (29 ₎ to obtain the converted flow rate Q _{p (20)} to the standard state of the flow rate by the specified test pressure, and displaying it.

[Modification]
In the above-described embodiment, the case where the converted flow rate Q _{ac (20)} measured by the existing technology is corrected to the converted flow rate Q _{p (20)} at the specified test pressure has been described. However, the actual test pressure P _ac and the environment are corrected. From the conditions, the converted flow rate Q _{p (20)} at the specified test pressure may be obtained as follows.

  If the flow velocity at the orifice is less than the speed of sound, using equation (10) to transform equation (12),

Is obtained. Here, the flow rate Q _ac is a value measured by the flow meter 20, the atmospheric pressure B and the temperature t _ac are measured as environmental conditions, the test pressure P _ac is measured by the test pressure gauge 13 as a gauge pressure, and the specified test pressure P _{Since p} is a predetermined value, equation (32) can be calculated from these values.

  Substituting equation (18) into equation (21) when the flow velocity at the orifice is sonic,

Is obtained. Also in this case, Q _{p (20)} can be calculated from the equation (33) using the measured values Q _ac , t _ac , P _ac , B and the specified test pressure value P _p .

  If the leakage flow is a viscous flow, substituting equation (31) into equation (29),

Is obtained, the measured value Q _ac, t _ac, can be calculated Q _{p (20)} using the P _ac, B and defines the test pressure value P _p from equation (34).

FIG. 6 shows a configuration of a flow rate measuring apparatus that realizes the above-described modified embodiment. The difference from FIG. 3 is that an arithmetic device 30 ″ provided with a corrected converted flow rate calculation unit 30K is provided instead of the flow rate conversion unit 30R and the flow rate correction unit 30C of the arithmetic device 30 ′. Is the same as in Fig. 3. The corrected converted flow rate calculation unit 30K uses any one of the above formulas (32), (33), and (34) corresponding to the leakage characteristics of the workpiece selected by the selection unit 34. , Calculates the converted flow Q _{p (20)} from the measured values Q _ac , t _ac , B and the specified test pressure value P _p taken into the storage unit 30M to the standard state of the leakage flow rate by the specified test pressure, and the display unit The measurement procedure is shown in FIG. 5 in place of the calculation of the conversion flow rate by multiplication of the conversion coefficient for the leakage characteristics of each workpiece and the calculation of the correction conversion flow rate by multiplication of the correction coefficient. It is only necessary to carry out either (33) or (34). I will omit the description.

[Example of flow measurement experiment]
7A, 8A, and 9A show the converted flow rates measured by the prior art when the test pressure is varied around each of the three types of workpieces when the specified test pressure is 200 hPa, 500 hPa, and 1000 hPa, respectively. In contrast, the corrected flow rate corrected by the present invention and the deviation of the corrected flow rate from the flow rate at the specified test pressure are shown in a table. However, the ambient atmospheric pressure B at the time of measurement was 1005 hPa, and the atmospheric temperature was 26.5 ° C. 7B, FIG. 8B, and FIG. 9B are graphs showing the values of the actually measured converted flow rate (indicated by x) and the corrected flow rate (indicated by o) in FIGS. 7A, 8A, and 9A. The axis indicates the test pressure (hPa), and the vertical axis indicates the flow rate (L / min). As is apparent from these graphs, in any case, the actually measured flow rate changes greatly due to variations in the test pressure, whereas the change in the correction flow rate is extremely small. When the variation of the test pressure with respect to the specified test pressure is within 10%, the deviation of the correction flow rate is within ± 1%. Therefore, according to the present invention, there is no need to increase the accuracy of setting the test pressure every time a workpiece is mounted. For example, if the test pressure is set to be within a range of ± 10% with respect to the specified test pressure, the specified test is performed. Measurement is possible with an error within ± 1% of the measured flow rate due to pressure, and setting is easy.

[Second Embodiment]
By the way, although the correction | amendment flow rate correction method about the leakage characteristic of the various workpieces mentioned above was demonstrated, in order to obtain | require the correction | amendment conversion flow rate Qp ₍₂₀₎ by Formula (12) when the flow velocity is less than a sonic speed, for example, Q _{ac (20)} needs to be calculated by equation (9). Although To calculate the conversion rate Q _{ac (20)} by equation (9) for measuring the flow rate Q _ac in differential pressure flow meter 20, the flow rate Q _ac is dependent on the gas density [rho _ac As is apparent from equation (4) To do. However, since the gas density ρ _ac depends on the gas pressure P _ac + B and the temperature t _ac , it is measured when at least one of the environmental temperature t _ac and the atmospheric pressure B changes even if the test pressure P _ac is set to be the same. This means that the flow rate Q _ac is changed. That is, the measured flow rate Q _ac differs depending on the time change of the environment where the flow rate measuring device is installed or the geographical environment where the device is installed, and as a result, the corrected conversion flow rate also differs. The same problem occurs in equation (18) when the flow velocity is sonic. Further, although the gas density is not included in the equation (23) in the case of the viscous flow, since the fluid viscosity η depends on the temperature of the fluid, the measured flow rate Q _ac changes if the measurement environment temperature changes. Have the same problem.

In the second embodiment, even if the test pressure fluctuates, the same result as the measured flow rate at the specified test pressure can be obtained, and the measured flow rate does not depend on the environmental change and is the same as the flow rate measured in the standard state. A flow rate measuring method will be described. That is, the leakage flow rate when fed a gaseous test pressure P _ac in any environment in the work here, converts the gas prescribed test pressure P _p in the standard state flow rate equivalent to the flow rate when applied to the work To display. Hereinafter, this converted flow rate is referred to as an equivalent flow rate.

[When the leakage characteristic of the workpiece is an orifice characteristic less than the speed of sound]
In FIG. 2A, when the atmospheric temperature of the measurement environment is t _ac ° C and the atmospheric pressure is B (hPa), the leakage flow rate (flow rate at the orifice inlet) Q _ac generated by _applying the test pressure P _ac is given by equation (4). It is done. When this is converted into the flow rate Q _Bac at the orifice outlet,

It becomes. Similarly, when the leakage amount Q _p generated by applying the specified test pressure P _p in the same environment is converted into the flow rate Q _Bp at the orifice outlet,

It becomes. From the equations (35) and (36), the following equation is obtained.

The density ratio is

Therefore, the following equation is obtained by substituting into equation (37) and transforming.

If B = 1013 hPa and t _p = t _ac = 20 ° C. in the standard state in equation (38), Q _Bp and Q _Bac are the _values when the specified test pressure P _p and the test pressure P _ac are applied, respectively. This means equivalent flow rates Q _Ep and Q _Eac , and the following equation is obtained.

In the equation (4), the flow rate Q _ac at the orifice inlet given by the equation (4) when the gas of the test pressure P _ac is supplied to the workpiece in the standard condition (atmospheric pressure 1013 hPa, temperature 20 ° C.) at the orifice outlet. When converted to a flow rate (ie equivalent flow rate Q _Eac ),

It becomes. Substituting equation (40) into equation (4),

Similar to equation (37a),

Therefore, Equation (40) becomes

It becomes. Giving a test pressure P _ac under standard conditions from the actual volumetric flow Q _ac the measurement environment (atmospheric pressure BhPa, temperature t _ac ° C.) in a defined test pressure P _p from displacement test pressure P _ac is measured given by equation (42) The equivalent flow rate Q _Eac at that time is calculated. The equivalent flow rate Q _Ep when the specified test pressure P _p is applied in the same measurement environment is obtained as follows by substituting Equation (42) into Equation (39).

Since the actual volume flow rate Q _ac is expressed by the converted flow rate Q _{ac (20)} in the equation (43), the following equation is obtained by substituting the equation (10) into the equation (43).

Here, E ₁ is called an equivalent coefficient. Note that the equivalent coefficient of the equation (44a) can be expressed as the following equation using the conversion factor R ₁ of the equation (9a).

As is apparent from the equation (44), the equivalent flow rate Q _Ep is obtained by multiplying the equivalent flow rate Q _{ac (20)} measured by the conventional technique by the equivalent coefficient E ₁ . Equivalent flow rate Q _Ep of equation (44) is the flow rate Q _ac (flow rate at the orifice inlet) measured by the flow meter when the test pressure P _ac is given to the workpiece in the environment of atmospheric pressure BhPa and temperature t _ac ℃ Therefore, in the standard state, it means that the equivalent flow rate Q _Ep which means the outflow rate to the ambient atmosphere when the gas of the specified test pressure P _p is given to the workpiece can be calculated. Therefore, this equivalent flow rate Q _Ep does not depend on the measurement environment.

[When workpiece leakage characteristics are orifice characteristics at sonic speed]
As described above, when (B + P ₁ ) / (B + P ₀ ) ≧ 1.89 in FIG. 2A, when the atmospheric temperature of the measurement environment is t _ac ° C and the atmospheric pressure is B (hPa), the test pressure P _The leakage flow rate (flow rate at the orifice inlet) Q _ac generated by giving _ac is given by the equation (14). When this is converted into the flow rate Q _Bac at the orifice outlet,

It becomes. Similarly, when the leakage amount Q _p generated by applying the specified test pressure P _p in the same environment is converted into the flow rate Q _Bp at the orifice outlet,

It becomes. From the equations (45) and (46), the following equation is obtained.

If B = 1013 hPa and t _p = t _ac = 20 ° C. in the standard state in equation (47), Q _Bp and Q _Bac mean equivalent flow rates Q _Ep and Q _Eac respectively, and the following equations are obtained. .

In the equation (45), when the atmospheric temperature is t _ac = 20 ° C. and the atmospheric pressure is B = 1013 hPa, the flow rate Q _Bac represents the equivalent flow rate Q _Eac , so the equivalent flow rate Q _Eac is expressed by the following equation: .

From the equations (49) and (14), the following equation is obtained.

On the other hand, the equivalent flow rate Q _Ep when the specified test pressure is applied is expressed as the following equation by substituting equation (50) into equation (48).

Is obtained. When the actual volume flow rate Q _ac of the equation (51) is expressed by the converted flow rate Q _{ac (20)} of the equation (18), the equation (51) becomes as follows.

Here, E ₂ is called an equivalent coefficient.

As is apparent from the equation (52), the equivalent flow rate Q _Ep is obtained by multiplying the equivalent flow rate Q _{ac (20)} measured by the conventional technique by the equivalent coefficient E ₂ . The equivalent coefficient E ₂ is expressed using the conversion coefficient R ₂ in the equation (18).

It is expressed. Equivalent flow rate Q _{Ep in} equation (52) is the flow rate Q _ac (flow rate at the orifice inlet) measured by the flow meter when the gas of test pressure P _ac is given to the workpiece in the environment of atmospheric pressure BhPa and temperature t _ac ℃ Therefore, in the standard state, it means that the equivalent flow rate Q _Ep which means the outflow rate to the atmosphere when the gas of the specified test pressure P _p is given to the workpiece can be calculated.

[When work leakage characteristics are viscous flow]
As schematically shown in FIG. 2B, when the leak hole of the workpiece is regarded as a narrow tube, the flow rate of the gas flowing through the narrow tube is affected by the viscosity as described above, and the flow rate of the gas flowing through the narrow tube is expressed by the equation (22). expressed. When the atmospheric temperature of the measurement environment is t _ac ° C and the atmospheric pressure is B (hPa), the leakage flow rate (flow rate in the narrow tube) Q ′ _ac generated by _applying the test pressure P _ac is given by equation (23). When this is converted into the flow rate Q _Bac at the outlet of the narrow tube,

It becomes. Similarly, when the leak amount Q _p generated by applying the specified test pressure P _p in the same environment is converted into the flow rate Q _Bp at the outlet of the narrow tube,

It becomes. Since the environmental temperature is the same, η _ac = η _p and the following equation is obtained from equations (53) and (54).

If B = 1013hPa and t _p = t _ac = 20 ° C in the standard condition in equation (55), Q _Bp and Q _Bac mean equivalent flow rates (flow rates at the narrow tube outlet) Q _Ep and Q _Eac , respectively. The following equation is obtained.

In the equation (53), when the measurement environment is a standard state, the flow rate Q _Bac means an equivalent flow rate QE _ac and is expressed by the following equation.

On the other hand, when the flow rate Q _Bac on the narrow tube outlet side in equation (53) is converted into the flow rate on the narrow tube inlet side, that is, the actual volume flow rate Q _ac to be measured, it is expressed by the following equation.

From the equations (57) and (58), the following equation is obtained.

The viscosity coefficient η of air is temperature-dependent, and the viscosity coefficient η _{t at} a temperature t ° C. can be approximately calculated by the following equation between a general temperature of 0 ° C. and 50 ° C.

η _t = 1.71 × (1 + 0.00257t) × 10 ^-5 (Pa ・ s) (60)
In the case of 20 ° C., η ₂₀ = 1.80 × 10 ⁻⁵ (Pa · s). Substituting this into equation (59) gives

Substituting equation (61) into equation (56) yields:

Is obtained. When the actual volume flow rate Q _ac of the equation (62) is expressed by the converted flow rate Q _{ac (20)} of the equation (31), the equation (62) becomes as follows.

Here, E ₃ is called an equivalent coefficient. As is apparent from the equation (63), the equivalent flow rate Q _Ep is obtained by multiplying the converted flow rate Q _{ac (20)} measured by the conventional technique by the equivalent coefficient E ₃ . The equivalent coefficient E ₃ is expressed using the conversion coefficient R ′ ₃ in the equation (31).

It becomes. Equivalent flow rate Q _{Ep in} equation (63) is the flow rate Q _ac (flow rate at the orifice inlet) measured by the flowmeter when the gas of test pressure P _ac is given to the workpiece in the environment of atmospheric pressure BhPa and temperature t _ac ℃ Therefore, in the standard state, it means that the equivalent flow rate Q _Ep which means the outflow rate to the atmosphere when the gas of the specified test pressure P _p is given to the workpiece can be calculated.

FIG. 10 shows the configuration of a flow rate measuring apparatus according to the second embodiment of the present invention, and FIG. 11 shows the process of the measuring method. A difference from the flow rate measuring device 230 in FIG. 3 is that an arithmetic unit 30 ′ ″ provided with a flow rate equivalent unit 30E is used instead of the flow rate correction unit 30C of the arithmetic unit 30 ′ in FIG. The configuration is exactly the same as in Fig. 3. Accordingly, the processing of the flow rate equivalent unit 30E in the arithmetic unit 30 '"is new, and the rest is the same as in Fig. 3. When the converted flow rate Q _{ac (20)} measured from the flow rate conversion unit 30R is given to the flow rate equivalent unit 30E, the equivalent coefficient E ₁ of the formula (44a) or the equivalent coefficient E of the formula (52a) is selected according to the leakage characteristics of the workpiece. ₂ or calculating the equivalent coefficient E ₃ of formula (63a), further multiplies the equivalence in terms of the flow rate Q _{ac (20)} by equation (44) or (52) or (63) to give the equivalent flow Q _Ep, This is given to the display unit 31.

  The atmospheric pressure B (hPa) of the measurement environment and the temperature t (° C.) of the gas supplied to the workpiece 40 are measured by the barometer 33 and the thermometer 32 and stored in the storage unit 30M of the arithmetic device 30 ″. 30M also stores a shape factor K and the like.

FIG. 11 shows a procedure for measuring the equivalent flow rate. The work 40 is attached to the downstream end of the test conduit 14 with the on-off valve 16 closed in advance. Until the converted flow rate of steps S1 to S4 is measured, it is the same as FIG. In step S54, using the specified test pressure P _p , the measured atmospheric pressure B, the atmospheric temperature t _ac , the test pressure P _ac and the converted flow rate Q _{ac (20)} , the formula (44a) or (52a) or (63a) The equivalent coefficient E _1, E _2, or E ₃ is calculated by the following, and the equivalent flow rate Q _Ep is further calculated by the formula (44), (52), or (63) and given to the display unit 31.

In the above description of each embodiment, the standard state has been described as the atmospheric pressure B = 1 atm (1013 hPa) and the temperature 20 ° (293 K), but may be any other predetermined atmospheric pressure B ₀ and temperature t _0. Is clear.

  The present invention can be used for measurement of gas flow rate.

Claims (16)

This is a method for measuring the flow rate of workpiece leakage.
(a) a process of measuring the atmospheric pressure B and temperature t _ac of the measurement environment;
(b) a process of measuring the test pressure P _{ac of the} gas supplied to the work through the flow meter;
(c) a process of measuring the actual volume flow rate Q _ac in a measurement environment with a flow meter;
(d) The actual volume flow rate Q _ac in the measurement environment is multiplied by a conversion factor to a predetermined standard state determined by the temperature t _ac , the atmospheric pressure B, and the test pressure P _ac to obtain a flow rate Q _{ac ( 20)}
(e) From the predetermined test pressure P _p determined in advance and the measured pressure B and the test pressure P _ac , the converted flow rate Q _{ac (20)} and the gas of the specified test pressure P _p were given to the workpiece. A process of calculating a correction coefficient for correcting to the hourly flow rate,
(f) A process of obtaining and displaying a corrected converted flow rate Q _{p (20)} when the specified test pressure P _p is applied to the workpiece by multiplying the converted flow rate Q _{ac (20)} by the correction coefficient. When,
A flow rate measuring method comprising: 2. The flow rate measuring method according to claim 1, wherein the leakage characteristic of the workpiece can be regarded as an orifice characteristic with a flow velocity less than the sonic velocity, and the step (e) includes the predetermined specified test pressure P _p and the measured atmospheric pressure. The correction coefficient C ₁ is calculated from B and the test pressure P _ac as follows:

The flow rate measurement method characterized by calculating by. 2. The flow rate measurement method according to claim 1, wherein the workpiece leakage characteristic is an orifice characteristic in which the flow velocity is a sonic velocity, and the step (e) includes the predetermined specified test pressure P _p and the measured atmospheric pressure B. And the correction coefficient C ₂ from the test pressure P _ac

The flow rate measurement method characterized by calculating by. 2. The flow rate measuring method according to claim 1, wherein the leakage characteristic of the workpiece can be regarded as a viscous flow, and the step (e) includes the predetermined specified test pressure _Pp , the measured pressure B and the measured test pressure P. _The above correction coefficient C ₃ is calculated from _ac

The flow rate measurement method characterized by calculating by. This is a method for measuring the flow rate of workpiece leakage.
(a) a process of measuring the atmospheric pressure B and temperature t _ac of the measurement environment;
(b) a process of measuring the test pressure P _{ac of the} gas supplied to the work through the flow meter;
(c) a process of measuring the actual volume flow rate Q _ac in a measurement environment with a flow meter;
(d) Multiplying the actual volume flow rate Q _ac in the measurement environment by a conversion factor to a predetermined standard state determined by the temperature t _ac , the atmospheric pressure B, and the test pressure P _ac , the converted flow rate Q _ac in the standard state ₍₂₀₎ conversion process,
(e) From the predetermined test pressure P _p determined in advance and the measured air pressure B and the test pressure P _ac , the converted flow rate Q _{ac (20)} is _supplied to the workpiece in the standard state with the gas at the specified test pressure. A process of calculating an equivalent coefficient for conversion to a flow rate equivalent to
(f) Multiplying the converted flow rate Q _{ac (20)} by the equivalent coefficient to obtain and display an equivalent flow rate Q _Ep when the specified test pressure P _p is applied to the workpiece in a standard state;
A flow rate measuring method comprising: 6. The flow rate measuring method according to claim 5, wherein the workpiece leakage characteristic can be regarded as an orifice characteristic with a flow velocity less than the sonic velocity, and the step (e) includes the predetermined specified test pressure P _p and the measured atmospheric pressure. The equivalent coefficient E ₁ is calculated from B and the test pressure P _ac

The flow rate measurement method characterized by calculating by. 6. The flow rate measuring method according to claim 5, wherein the leakage characteristic of the work is a case where the flow velocity can be regarded as an orifice characteristic having a sonic velocity, and the step (e) includes the predetermined specified test pressure P _p and the measured atmospheric pressure B. And the correction coefficient E ₂ from the test pressure P _ac

The flow rate measurement method characterized by calculating by. 6. The flow rate measurement method according to claim 5, wherein the leakage characteristic of the workpiece can be regarded as a viscous flow, and the step (e) includes the predetermined specified test pressure P _p , the measured pressure B and the measured test pressure P. _{From ac} , the correction coefficient E ₃ is

The flow rate measurement method characterized by calculating by. It is a flow measurement device for workpiece leakage,
A barometer for measuring the atmospheric pressure B of the measurement environment;
A thermometer for measuring the temperature t _{ac of the} measurement environment;
A pressure regulating valve for adjusting the test pressure P _{ac of the} gas supplied to the workpiece from the pneumatic pressure through the test conduit;
A flow meter that is inserted in series in the test conduit downstream of the pressure regulating valve and measures the actual volume flow rate Q _ac of the gas supplied to the workpiece;
A test pressure gauge for measuring the test pressure P _{ac of the} gas supplied to the workpiece through the flow meter;
The temperature t _ac and the pressure B and the test pressure P conversion rate of the conversion factor to a predetermined standard state determined by the _ac in the standard state by multiplying the actual volumetric flow rate Q _ac in the measurement environment Q _{ac (20)} A flow rate conversion unit for converting to
A correction coefficient for correcting the converted flow rate to the flow rate when the gas of the specified test pressure is applied to the workpiece is calculated from the predetermined specified test pressure P _p and the measured pressure B and the measured test pressure P _ac. A flow rate correction unit that multiplies the converted flow rate Q _{ac (20)} by the correction coefficient to obtain a corrected converted flow rate Q _{p (20)} when the specified test pressure P _p is applied to the workpiece;
A display unit for displaying the corrected converted flow rate Q _{p (20)} ;
A flow rate measuring device comprising: 10. The flow rate measuring apparatus according to claim 9, wherein the workpiece leakage characteristic is considered to be an orifice characteristic having a flow velocity less than the sonic velocity, and the flow rate correction unit is configured to determine the predetermined test pressure P _p and the measured atmospheric pressure B. And the correction coefficient C ₁ from the test pressure P _ac

The flow rate measuring device characterized by calculating by. 10. The flow rate measuring apparatus according to claim 9, wherein the workpiece leakage characteristic is a case where the flow velocity can be regarded as an orifice characteristic having a sonic velocity, and the flow rate correction unit is configured to determine a predetermined specified test pressure P _p and the measured atmospheric pressure B and The correction coefficient C ₂ is calculated from the test pressure P _ac

The flow rate measuring device characterized by calculating by. 10. The flow rate measuring apparatus according to claim 9, wherein the leakage characteristic of the workpiece can be regarded as a viscous flow, and the flow rate correcting unit is configured to determine the predetermined test pressure P _p and the measured atmospheric pressure B and the test pressure P _ac. To the correction coefficient C ₃

The flow rate measuring device characterized by calculating by. It is a flow measurement device for workpiece leakage,
A barometer for measuring the atmospheric pressure B of the measurement environment;
A thermometer for measuring the temperature t _{ac of the} measurement environment;
A pressure regulating valve for adjusting the test pressure P _{ac of the} gas supplied to the workpiece from the pneumatic pressure through the test conduit;
A flow meter that is inserted in series in the test conduit downstream of the pressure regulating valve and measures the actual volume flow rate Q _ac of the gas supplied to the workpiece;
A test pressure gauge for measuring the test pressure P _{ac of the} gas supplied to the workpiece through the flow meter;
The temperature t _ac and the pressure B and the test pressure P conversion rate of the conversion factor to a predetermined standard state determined by the _ac in the standard state by multiplying the actual volumetric flow rate Q _ac in the measurement environment Q _{ac (20)} A flow rate conversion unit for converting to
From the predetermined test pressure P _p determined in advance and the measured atmospheric pressure B and the test pressure P _ac , the converted flow rate Q _{ac (20)} and the gas at the specified test pressure P _p are given to the workpiece in a standard state. A flow rate equivalent unit for calculating an equivalent coefficient to be converted into an equivalent flow rate, and multiplying the converted flow rate Q _{ac (20)} by the equivalent coefficient to obtain an equivalent flow rate Q _Ep ;
A display for displaying the equivalent flow rate Q _Ep ,
A flow rate measuring device comprising: 14. The flow rate measuring apparatus according to claim 13, wherein the workpiece leakage characteristic is considered to be an orifice characteristic having a flow velocity less than the sonic velocity, and the flow rate equivalent portion is determined by the predetermined specified test pressure _Pp and the measured atmospheric pressure B. And the equivalent coefficient E ₁ from the test pressure P _ac

The flow rate measuring device characterized by calculating by. 14. The flow rate measuring apparatus according to claim 13, wherein the characteristic of workpiece leakage is a case where the flow velocity can be regarded as an orifice characteristic having a sonic velocity, and the flow rate equivalent part includes a predetermined specified test pressure _Pp and the measured atmospheric pressure B and From the test pressure P _ac , the equivalent coefficient E ₂ is

The flow rate measuring device characterized by calculating by. 14. The flow rate measuring apparatus according to claim 13, wherein the leakage characteristic of the workpiece can be regarded as a viscous flow, and the flow rate equivalent part includes a predetermined specified test pressure _Pp , the measured atmospheric pressure B, and the test pressure _Pac. The equivalent coefficient E ₃ is given by

The flow rate measuring device characterized by calculating by.

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