JP2000214039A - Self-recording manometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the precision of an airtightness and leakage test by preventing pressure variation with temperature from being misdecided. SOLUTION: The self-recording manometer measures pressure and temperature by a temperature and pressure measurement part 24 under the control of a measurement control part 22 in a specific periodic measurement timing measured by a timer part 23, and finds the quantity of pressure variation corresponding to the quantity of temperature variation from an initial temperature value by a pressure correction part 25 and subtracts or adds it from or to the pressure measured value to correct the pressure variation with temperature. Then a pressure variation decision part 26 compares the initial pressure value with the corrected pressure temperature value to decide whether or not there is pressure variation from whether or not the pressure difference is larger than a specific value 10 Pa. When pressure variation is decided, the initial pressure value and initial temperature value are replaced with the current pressure measured value and temperature measured value to update the initial values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring pressure fluctuations in a gas pipe or the like, and for use in an airtightness test and a leak test performed at the completion of LP gas piping work or at the start of supply of the LP gas. Self-recording pressure gauge used for pressure measurement for a wide range of purposes.

[0002]

2. Description of the Related Art Self-recording pressure gauges are used in, for example, an airtightness test performed when a new gas pipe is provided. The airtightness test is a test for injecting air before flowing the actual gas and pressurizing the gas to a specified pressure, and confirming that there is no leakage for a predetermined time.

A conventional self-recording pressure gauge (electric diaphragm pressure gauge) applies a predetermined time (for example, 30 seconds) when a measurement start button is pressed after pressure is applied to a pipe to be measured. After securing the stabilization time, the actual pressure measurement is started. When the measurement is started, the pressure measurement value at that time is registered as an initial pressure (recorded on paper or stored in a memory or the like), and the pressure is measured for a set measurement time. The airtightness such as leakage was determined based on the difference between the measured value and the registered initial pressure as the final pressure.

In recent years, as such a self-recording pressure gauge,
There has been proposed a digital type in which a microcomputer is built in, a pressure measurement value is obtained by calculation or the like based on an output of a pressure sensor, and the pressure measurement value is digitally displayed on a display unit such as a liquid crystal display panel. The conventional digital self-recording pressure gauge has only a pressure sensor as a sensor unit, and converts a voltage value corresponding to a detected pressure output from the pressure sensor into a pressure measurement value by calculation or the like and displays it on a display unit. It has such a configuration. When the measured pressure value is displayed as a digital value in this way, a display resolution (minimum display step) of the display unit is set to, for example, 10 Pa.

[0005] In the pressure measurement by the self-recording pressure gauge, if a temperature change occurs within a certain volume after the start of the measurement, the boiling
The pressure value fluctuates due to Charles' law (the gas volume V is inversely proportional to the pressure P and proportional to the absolute temperature T).
For example, depending on the type of the test gas, a temperature change of 1 ° C. causes a pressure fluctuation of about 4.71 Pa. In this case, the pressure value changes in proportion to the rise and fall in temperature.

When performing an airtight test, pressure is applied to a pipe or the like to secure the above stabilization time, and then a predetermined measurement time (5
During this period, the pressure in the pipe is measured to check for airtightness and leakage. When affected by a temperature change during the airtight test, the pressure value fluctuates, and it becomes difficult to determine whether the pressure fluctuation is due to leakage or temperature.

[0007]

As described above, in the conventional self-recording pressure gauge, if the temperature is affected during the pressure measurement, the pressure value fluctuates. However, there is a problem that it is difficult to determine whether the difference is due to the temperature or the temperature. When the temperature rises, the pressure value rises, so that even if a leak actually occurs, a pressure drop is not detected, so that there is a problem that the leak cannot be confirmed on recording. In addition, when the temperature is decreased, the pressure value is decreased. Therefore, even if the pressure is actually normal, the pressure decrease is detected, and there is a problem that there is a possibility that the pressure is erroneously determined to be leaking.

The present invention has been made in view of the above circumstances, and an object of the present invention is to always perform an accurate pressure measurement by excluding a pressure fluctuation due to a temperature change in a target space. An object of the present invention is to provide a self-recording pressure gauge capable of improving the accuracy of an airtightness / leakage test.

[0009]

In order to achieve the above object, an invention according to claim 1 is a self-recording pressure gauge for performing pressure measurement of a target space for a predetermined measurement time and displaying a pressure measurement value or the like. Pressure detection means for detecting the gas pressure of the target space, temperature detection means for detecting the temperature of the target space, and a pressure measurement value at the start of measurement based on the outputs of the pressure detection means and the temperature detection means. And an initial value storage means for obtaining a temperature measurement value and storing it as an initial pressure value and a temperature initial value, and a temperature corresponding to the initial pressure value in a pressure measurement value within a measurement time based on outputs of the pressure detection means and the temperature detection means. Pressure temperature change amount detection means for obtaining a pressure change amount due to change; pressure correction means for obtaining a pressure temperature correction value obtained by correcting the pressure change amount due to the temperature change; A pressure fluctuation determining means determines the presence or absence of pressure fluctuations by comparing the pressure value, but having a.

[0010] The invention described in claim 2 is the same as the claim 1.
In the self-recording pressure gauge described, the pressure fluctuation determining means,
When it is determined that there is a pressure fluctuation in the determination of the pressure fluctuation, the initial pressure value in the initial value storage means is replaced with a pressure / temperature correction value at the time of the fluctuation determination.

[0011] The invention according to claim 3 is based on claim 1.
The self-recording pressure gauge according to the description, further comprising a display means for displaying at least an initial pressure value as the pressure measurement value, the pressure fluctuation determination means, when it is determined that there is pressure fluctuation in the determination of the pressure fluctuation, in the display means The display of the initial pressure value is updated to the pressure / temperature correction value at the time of the fluctuation determination.

The invention described in claim 4 is the first invention.
In the self-recording pressure gauge described, the pressure fluctuation determining means,
When the difference between the pressure temperature correction value and the initial pressure value is equal to or larger than a predetermined value, it is determined that there is a pressure change.

[0013] The invention described in claim 5 provides the invention according to claim 4.
In the self-recording pressure gauge described, the pressure fluctuation determining means,
The present invention is characterized in that pressure fluctuation determination is performed using the display resolution of the display means for displaying the measured pressure value as the predetermined value.

In the above configuration, the initial pressure value and the temperature initial value at the start of the measurement are stored, the pressure change amount due to the temperature change with respect to the initial pressure value is obtained, and the pressure temperature correction value is calculated by correcting the pressure change amount. Then, by comparing the pressure-temperature correction value with the initial pressure value to determine the presence or absence of pressure fluctuation, the pressure measurement value within the measurement time excludes the pressure fluctuation due to the temperature change in the target space. A true pressure measurement that is not affected by changes is obtained, and a correct pressure fluctuation can always be detected. Therefore, an appropriate airtightness / leakage test can be performed without the influence of a temperature change in the measurement environment, and the accuracy of the airtightness / leakage test can be improved.

When it is determined that there is a pressure fluctuation,
By updating the stored initial pressure value to the pressure / temperature correction value at the time of this fluctuation determination, or by updating the display of the initial pressure value on the display means to this pressure / temperature correction value, the presence / absence of accurate pressure fluctuation can be determined. This allows the user to always see the correct pressure measurement during the measurement time.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall front view of a self-writing pressure gauge with a temperature correction function according to an embodiment of the present invention, FIG. 2 is a block diagram showing a functional configuration of the self-writing pressure gauge in the present embodiment, and FIG. 5 is a flowchart illustrating a first embodiment of an operation procedure.

In this embodiment, an example of the configuration of a digital type self-recording pressure gauge with a temperature correction function will be described. As shown in FIG. 1, the self-recording pressure gauge 1 is an electronic pressure gauge that includes a control microcomputer therein and displays measured values in digital values.

The self-recording pressure gauge 1 includes a power switch 2, a measurement mode selection switch 3 for switching and selecting a measurement mode such as a normal mode, a periodic measurement mode, and a reference value comparison mode, and a start button for instructing the start of measurement. 4, a display unit 5 such as a liquid crystal display panel (LCD) provided as a display unit for displaying a pressure measurement value, etc., a printing unit 6 such as a printer for printing out measurement data, a gas for taking in a test gas A plug 7, a numeric keypad 8 for operating various settings, a time setting button 9 for setting a time such as a timer, a piping capacity button 10 for operating a piping capacity value, and a printing unit 6 for printing. Print button 11 to be operated when printing out, printing section 6
And a paper feed button 12 that is operated when the recording paper is fed. The display unit 5 includes an initial value display 13, a maximum value, a minimum value of the measured pressure, a measured value display 14 such as a closing pressure, a pipe volume display 15, a measurement time display 16, an overpressure display 17, a battery replacement display 18, and An in-measurement display 19 is provided.

As shown in the block diagram of FIG. 2, the self-recording pressure gauge 1 has a sensor section 20 having a pressure sensor 20a corresponding to pressure detecting means and a temperature sensor 20b corresponding to temperature detecting means, A D conversion unit 21 and a measurement control unit 22 including a microcomputer for controlling the entire apparatus.
And a warning unit 28 for giving a warning at the time of abnormality, and a display unit 5 and a printing unit 6. The measurement control unit 22
Performs various operation controls related to pressure measurement.
It has a ROM, a RAM, and the like, and has a timer 23, a temperature / pressure measuring unit 24 for calculating a pressure measurement value and a temperature measurement value, a pressure / temperature change detection unit, and a pressure correction unit. A pressure correcting unit 25 having a function, a pressure fluctuation determining unit 26 having a function of a pressure fluctuation determining unit, and a memory unit 27 having a function of an initial value storing unit are provided.

The pressure sensor 20a is, for example, an electric diaphragm type sensor and outputs an analog voltage value as a measured pressure value via a differential amplifier or the like. As the temperature sensor 20b, for example, a thermopile sensor is used, and outputs an analog voltage value as a measured temperature value via a differential amplifier or the like. These pressure sensors 20
a and the temperature sensor 20b are built in the self-recording pressure gauge main body,
It is configured to detect pressure and temperature in a target space such as a pipe. The A / D conversion unit 21 converts the analog voltage value from the sensor unit 20 into a predetermined digital detection value so that the microcomputer of the measurement control unit 22 can process the analog voltage value. The warning means 26 warns the user with a buzzer sound, a warning display, or the like.

The timer section 23 has a measurement time timer for measuring the measurement time, a periodic measurement timer for periodically performing the pressure fluctuation judgment, and the like. Note that these timers are functionally separated for the sake of explanation, and can of course be shared. The timer unit 23 may be built in the measurement control unit 22 or provided separately outside. The temperature / pressure measurement unit 24 obtains a pressure measurement value and a temperature measurement value based on the output of the sensor unit 20, and calculates a pressure change amount together with the initial pressure value and the temperature initial value and the pressure measurement value and the temperature measurement value within the measurement time. It is calculated and registered in the memory unit 27. The pressure correction unit 25 corrects a pressure change due to a temperature change based on the pressure change amount to obtain a pressure-temperature correction value from which a temperature effect is removed. The pressure fluctuation determining unit 26 determines whether or not there is an actual pressure fluctuation in a pipe to be measured or the like by comparing the pressure temperature correction value with the initial pressure value. Memory unit 27
Is configured to include a ROM, a RAM, and the like, stores the initial pressure value and the like, and stores a conversion formula or a conversion table of a pressure change with respect to a temperature change.

Next, the operation of the self-recording pressure gauge of this embodiment will be described. When performing pressure measurement, first, as a preparation stage before the start of measurement, the user turns on the power switch 2 of the self-recording pressure gauge 1 shown in FIG. 1 and selects a measurement mode with the measurement mode selection switch 3. Next, the user presses buttons such as the pipe capacity button 10 and the time setting button 9 to perform a predetermined input from the ten keys 8. For example, when setting the entire measurement time (for example, 5 to 24 minutes), the user presses the time setting button 9 and inputs 5 → 0 → 0 from the numeric keypad 8 to display “00:” in the measurement time display 16 on the display unit 5. Set while checking the display such as “05:00”. Subsequently, the pipe capacity and the regular measurement time in the regular monitoring are set in the same manner.

Next, when the start button 4 is pressed, the measurement is started, and the pressure and temperature of a gas such as a test gas (air in the case of a leak test) taken in from the gas stopper 7 are detected by the sensor unit 20. The analog voltage value output from the sensor unit 20 is converted into a digital detection value by the A / D conversion unit 21 and then input to the measurement control unit 22 for processing. When a predetermined stabilization time has elapsed, the measurement control unit 22 uses the pressure measurement value and the temperature measurement value calculated by the temperature and pressure measurement unit 24 as initial values at the start of measurement, and stores them in the memory or the register ( (Not shown) or the like. At this time, the initial pressure value and the like are displayed in the area of the initial value display 13 on the display unit 5.

Thereafter, during the set measurement time, the actual pressure measurement is repeatedly performed at a predetermined cycle, and the temperature pressure measurement unit 24 obtains the pressure measurement value and the temperature measurement value. Then, based on the obtained pressure measurement value and temperature measurement value, the pressure correction unit 25 calculates a pressure-temperature correction value obtained by correcting the pressure change due to the temperature change, and the pressure fluctuation determination unit 26 calculates the pressure-temperature correction value and the initial pressure. The presence / absence of pressure fluctuation is determined by comparison with the value, and the measurement result is displayed on the display unit 5. At this time, the in-measurement display 19 is turned on. At the end of the measurement time, the pressure measurement value at the end of the measurement is displayed as the final value, the stored initial value is read out, and the pressure difference is obtained by the equation (initial value−final value) = pressure difference. This pressure difference is displayed as a differential pressure value. In addition, the maximum value, the minimum value, the average value, and the like of the pressure measurement values can be displayed after the measurement is completed.

When the display data of the display unit 5 is printed out by the printing unit 6, the print data can be printed on paper by pressing the print button 11 and the paper feed button 12.

Next, a first embodiment of the processing at the time of pressure measurement will be described in detail with reference to the flowchart of FIG. The processing of this flowchart is executed in the timer unit 23, the temperature / pressure measurement unit 24, the pressure correction unit 25, the pressure fluctuation determination unit 26, and the memory unit 27 of the measurement control unit 22.

At the start of measurement, the measurement control unit 22 starts a measurement time timer of the timer unit 23 based on the set value (step S31). At this time, the temperature / pressure measurement unit 24 calculates the pressure measurement value and the temperature measurement value based on the digital pressure and temperature detection values detected by the sensor unit 20 and converted by the A / D conversion unit 21 and input. An initial value is obtained, and stored and registered in the memory unit 27 as an initial pressure value (pressure 1) and an initial temperature value (temperature 1) (step S3).
2). The initial pressure value and the initial temperature value are displayed on the display unit 5.
This is displayed on the initial value display 13 above.

Next, the measurement control unit 22 starts a periodic measurement timer of the timer unit 23 for monitoring the pressure at a predetermined cycle within the set constant measurement time (step S).
33). Subsequently, it is determined whether the measurement time timer has expired (counted up) (step S3).
4), determine the end of the measurement time. Here, if it is still within the measurement time, it is subsequently determined whether or not the periodical measurement timer has expired (counted up) (step S35). Here, if the regular measurement timer has not yet expired and the timing of the periodic measurement has not come, the process returns to step S34 to repeat the timer determination process, and waits until the timing of the periodic measurement. The determination of the measurement time timer and the periodic measurement timer here refers to the state of the write flag in the memory unit 27 and determines whether or not the timer is over.

When it is determined in step S35 that the regular measurement timer has expired and the regular measurement timing has come, the temperature and pressure measurement unit 24 obtains the pressure measurement value and the temperature measurement value at this time, and determines the pressure 2 and the temperature, respectively. 2 is stored in the memory unit 27 (step S36). Then, in the pressure correction unit 25, the difference between the current temperature measurement value (temperature 2) and the initial temperature value (temperature 1) (Δtemperature = temperature2−temperature1)
It is determined whether or not this temperature difference (Δ temperature) is greater than 0 (temperature 2−temperature 1> 0) (step S3).
7).

If the Δ temperature is greater than 0, that is, if the temperature rise has occurred and the change temperature value has become a positive value in step S37, the change in pressure with respect to the temperature change of the program stored in the memory unit 27 By substituting the value of Δtemperature into the conversion formula, the amount of pressure change corresponding to the temperature change is calculated, and this is stored in the memory unit 27 as the pressure change 1 (step S38). Note that a conversion table or the like can be used instead of the conversion formula. Then, the amount of pressure change (pressure change 1) is subtracted from the current measured pressure value (pressure 2) (pressure 2-pressure change 1) to obtain a pressure-temperature correction value (pressure 3) in which the temperature change is corrected (pressure 3). Step S39). As a result, it is possible to obtain a corrected value of the pressure measurement value during the current measurement time while excluding the influence of the temperature rise.

Next, the pressure fluctuation determining section 26 compares the initial pressure value (pressure 1) with the finally corrected pressure-temperature correction value (pressure 3) to determine the absolute value of the difference between these values. Then, it is determined whether or not this pressure difference is equal to or more than a predetermined value (here, 10 Pa) (| pressure 1−pressure 3 | ≧ 10 Pa) (step S40). Here, the difference between pressure 3 and pressure 1 is 1
If it is smaller than 0 Pa, it is determined that there is no pressure fluctuation, and the process returns to step S33. The predetermined value 10 Pa corresponds to the display resolution on the display unit 5. The presence or absence of a pressure change is determined by whether or not there is a pressure change amount that causes a change in the display of the pressure measurement value in a state where the influence of the temperature change is corrected. The decision is made.

If it is determined in step S40 that the difference between the pressure 3 and the pressure 1 is equal to or greater than 10 Pa, the pressure fluctuation determining unit 26 determines that there is pressure fluctuation, and sets the pressure temperature correction value at this time as an initial pressure value. (Pressure 3 → Pressure 1), the temperature measurement value is used as an initial temperature value (Temperature 2 → Temperature 1), and the initial values of temperature and pressure are replaced. Then, the new initial pressure value and new initial temperature value are stored and registered in the memory unit 27, and displayed on the display unit 5 to update the display data (step S4).
1).

On the other hand, if the Δ temperature is smaller than 0, that is, if the temperature change has become a negative value due to the temperature drop in the determination of step S37, the pressure correction unit 25 stores the memory unit 27 in the same manner as in step S38. Substituting the value of Δtemperature into the conversion equation of the pressure change with respect to the temperature change of the program stored in the section (2), calculates the pressure change amount corresponding to the temperature change, and stores this as the pressure change 2 in the memory unit 27 ( Step S42). Then, the pressure change amount (pressure change 2) is added to the current measured pressure value (pressure 2) (pressure 2 + pressure change 2), and a pressure-temperature correction value (pressure 4) obtained by correcting the temperature change is obtained (step). S43). This makes it possible to obtain a corrected value of the pressure measurement value during the current measurement time, excluding the influence of the temperature drop.

Next, the pressure fluctuation determining section 26 compares the initial pressure value (pressure 1) with the corrected pressure temperature correction value (pressure 4) to determine the absolute value of the difference between these values. Whether the difference is equal to or greater than a predetermined value of 10 Pa (| pressure 1-pressure 4
| ≧ 10 Pa) is determined (step S44). Here, when the difference between the pressure 4 and the pressure 1 is smaller than 10 Pa,
It is determined that there is no pressure change, and the process returns to step S33.

If it is determined in step S44 that the difference between the pressure 4 and the pressure 1 is equal to or greater than 10 Pa, the pressure fluctuation determination unit 26
Determines that there is pressure fluctuation, sets the pressure-temperature correction value at this time as the initial pressure value (pressure 4 → pressure 1), and sets the measured temperature value as the initial temperature value (temperature 2 → temperature 1). Replace the initial value. Then, the new initial pressure value and the new initial temperature value are stored and registered in the memory unit 27, and displayed on the display unit 5 to update the display data (step S45).

The above processing is repeated, and when the measurement time timer has expired and the measurement time has elapsed in the judgment of step S34, the measurement of pressure and temperature is terminated (step S4).
6). Then, the updated initial pressure value (pressure 1) and the updated initial temperature value (temperature 1) up to the present, that is, the measurement results of the pressure measurement value and the temperature measurement value corrected so as to remove the influence of the temperature change are measured and recorded. Is printed out from the printing unit 6 (step S47).

As described above, according to the present embodiment, the difference between the temperature measurement value measured at each predetermined periodic measurement timing and the initial temperature value is obtained, and the pressure change amount corresponding to this temperature change amount is obtained. With the configuration in which the pressure fluctuation due to the temperature change is corrected by subtracting or adding from the measured value, the influence of the temperature change on the pressure measured value is removed, and accurate pressure fluctuation can be detected. This makes it possible to always perform accurate and quick pressure measurement, eliminate erroneous determination of pressure fluctuation due to temperature change, and improve the accuracy of the airtightness / leakage test.

Next, a second embodiment of the processing at the time of pressure measurement will be described with reference to the flowchart of FIG. FIG. 4 is a flowchart showing a second embodiment of the measuring operation procedure of the self-recording pressure gauge.

In the second embodiment, a part corresponding to the operation of the temperature / pressure measuring unit 24 in the first embodiment is changed. In the first embodiment, step S3 in FIG.
Before performing the temperature and pressure measurement processing in step 6, the states of the measurement time timer and the periodic measurement timer are determined in steps S33 to S35, and the temperature and pressure are measured at each periodic measurement timing. On the other hand, in the second embodiment, as shown in FIG. 4, before performing the temperature and pressure measurement processing in step S55, steps S53 and S53 are performed.
At 54, the state of the measurement time timer is determined, and at the same time, it is determined whether there is a pressure change exceeding a predetermined value. When the pressure change exceeds a predetermined value, the temperature and pressure are measured. That is, instead of the periodic monitoring in which the pressure measurement is performed at every periodic measurement timing and the pressure change is checked by the setting of the periodic measurement timer, the predetermined value 10
The difference is that the processing procedure is made more efficient so that pressure is measured only when Pa is set as a threshold value and the threshold value is exceeded.

At the start of measurement, the measurement control unit 22 starts a measurement time timer of the timer unit 23 based on the set value (step S51). At this time, the temperature / pressure measurement unit 24 calculates the pressure measurement value and the temperature measurement value based on the digital pressure and temperature detection values detected by the sensor unit 20 and converted by the A / D conversion unit 21 and input. An initial value is obtained, and stored and registered in the memory unit 27 as an initial pressure value (pressure 1) and an initial temperature value (temperature 1) (step S5).
2). The initial pressure value and the initial temperature value are displayed on the display unit 5.
This is displayed on the initial value display 13 above.

Next, the measurement control unit 22 determines whether the measurement time timer has expired (counted up) (step S53), and determines the end of the measurement time. Here, if it is still within the measurement time, it is subsequently determined whether there is a pressure change exceeding a predetermined value (here, 10 Pa) (step S54). The determination of the pressure change amount is A / D
What is necessary is just to perform based on the output of the conversion part 21, or the output of the temperature-pressure measurement part 24.

If it is determined in step S54 that a pressure change exceeding 10 Pa has not occurred, the process returns to step S53 to repeat the timer determination processing and the pressure change determination processing, and waits until a pressure change equal to or more than a predetermined value occurs. Then, when a pressure change exceeding 10 Pa occurs in the determination of step S54, the pressure measurement value and the temperature measurement value at this time are obtained by the temperature and pressure measurement unit 24 and stored in the memory unit 27 as Pressure 2 and Temperature 2 respectively. (Step S55).

The subsequent steps S56 to S66 are the same as the steps S37 to S47 in the first embodiment, and will not be described here. That is, the difference between the temperature measurement value measured when a pressure change equal to or more than a predetermined value occurs and the initial temperature value is obtained, and the pressure change amount corresponding to the temperature change amount is obtained and subtracted or added from the pressure measurement value. Then, the pressure fluctuation due to the temperature change is corrected to the pressure fluctuation due to the temperature change, and the presence or absence of the pressure fluctuation is determined in a state where the influence of the temperature change on the measured pressure value is removed.

As described above, according to the present embodiment, similarly to the first embodiment, the pressure change amount corresponding to the temperature change amount from the initial temperature value is obtained and subtracted or added from the measured pressure value. By compensating for the pressure fluctuation due to temperature change, it is possible to remove the influence of temperature change on the pressure measurement value,
The effect that an accurate pressure fluctuation can be detected is obtained. In addition, 10 Pa as a reference value for pressure fluctuation determination
(The display resolution of the display unit) The pressure fluctuation is determined by performing pressure measurement and temperature correction only when there is a pressure change greater than or equal to the above. This eliminates waste of the measurement procedure during the airtightness / leakage test. Efficient pressure measurement can be performed.

In the above embodiment, the operation for updating the measured value display on the display unit when it is determined that there is a pressure change has been described. However, the present invention is not limited to this. No type (measurement method that displays the initial pressure value at the start of measurement and does not update the display of the pressure value until the end of measurement, but updates the display to the current pressure value at the end of measurement)
Also in the self-recording pressure gauge described above, the configuration of the measurement control unit of the present invention can be applied in the same manner by making the microcomputer always (periodically) monitor the pressure with the same logic internally.

According to the above-described embodiment, airtightness and
It is possible to prevent erroneous detection of pressure fluctuation due to temperature change during a predetermined measurement time of the leak test, and it is possible to accurately detect only true pressure fluctuation regardless of temperature. Therefore,
The display of the pressure measurement value is not updated by the temperature change, and the display of the measurement value is stabilized. In addition, airtightness / leakage determination can be performed easily and accurately. Further, it is not necessary for the user to monitor the temperature change and correct the pressure measurement value by calculation by himself, thereby making it possible to efficiently perform the pressure measurement. As a result, a more accurate airtightness / leakage test can always be performed regardless of the measurement environment, and the accuracy of the test can be improved.

[0047]

As described above, according to the present invention, the initial pressure value and the temperature initial value at the start of the measurement are stored, the pressure change due to the temperature change with respect to the initial pressure value is obtained, and this pressure change is calculated. Calculate the corrected pressure-temperature correction value and compare the pressure-temperature correction value with the initial pressure value to determine the presence or absence of pressure fluctuation. Minutes can be excluded, a true pressure measurement that is not affected by temperature changes can be obtained, and accurate pressure measurement can always be performed.
Therefore, correct pressure fluctuation can always be detected without the influence of temperature change in the measurement environment, and a proper airtightness / leakage test can be performed, so that the accuracy of the airtightness / leakage test can be improved.

[Brief description of the drawings]

FIG. 1 is an overall front view of a self-writing pressure gauge with a temperature correction function according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a functional configuration of a self-recording pressure gauge according to the present embodiment.

FIG. 3 is a flowchart showing a first embodiment of a measuring operation procedure of the self-recording pressure gauge.

FIG. 4 is a flowchart showing a second embodiment of the measuring operation procedure of the self-recording pressure gauge.

[Description of Signs] 1 Self-recording pressure gauge 2 Power switch 3 Measurement mode changeover switch 4 Start button 5 Display section 6 Printing section 13 Initial value display 14 Measurement value display 20 Sensor section 20a Pressure sensor 20b Temperature sensor 21 A / D conversion section 22 Measurement control unit 23 Timer unit 24 Temperature / pressure measurement unit 25 Pressure correction unit 26 Pressure fluctuation determination unit 27 Memory unit 28 Warning means

Claims (5)

[Claims] 1. A self-recording pressure gauge for performing pressure measurement of a target space over a predetermined measurement time and displaying a pressure measurement value, etc., wherein: a pressure detecting means for detecting a gas pressure of the target space; Temperature detection means for detecting the temperature of the pressure sensor, and an initial value storage for obtaining a pressure measurement value and a temperature measurement value at the start of the measurement based on the outputs of the pressure detection means and the temperature detection means and storing them as an initial pressure value and a temperature initial value. Means, based on outputs of the pressure detection means and the temperature detection means, a pressure-temperature change detection means for obtaining a pressure change amount due to a temperature change with respect to the initial pressure value in a pressure measurement value within a measurement time; and a pressure due to the temperature change. Pressure correction means for obtaining a pressure-temperature correction value obtained by correcting the amount of change; and a pressure fluctuation determination for comparing the pressure-temperature correction value with the initial pressure value to determine the presence or absence of a pressure fluctuation. A self-recording pressure gauge, comprising: 2. The pressure fluctuation judging means, when judging that there is a pressure fluctuation in the judgment of the pressure fluctuation, replacing the initial pressure value of the initial value storage means with a pressure temperature correction value at the time of the fluctuation judgment. The self-recording pressure gauge according to claim 1, wherein 3. A display means for displaying at least an initial pressure value as the pressure measurement value, wherein the pressure fluctuation determining means determines an initial pressure in the display means when it is determined that the pressure fluctuation is present in the determination of the pressure fluctuation. The self-recording pressure gauge according to claim 1, wherein the display of the value is updated to the pressure temperature correction value at the time of the fluctuation determination. 4. The pressure fluctuation determining means determines that there is pressure fluctuation when a difference between the pressure temperature correction value and the initial pressure value is equal to or greater than a predetermined value.
Self-recording pressure gauge as described in. 5. The self-recording pressure gauge according to claim 4, wherein the pressure fluctuation determining means performs the pressure fluctuation determination using a display resolution of a display means for displaying a pressure measurement value as the predetermined value.