JPH0540442Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a gas leakage amount measuring device that measures the amount of leaked gas such as gas that permeates through a semipermeable membrane.

[Prior Art] FIG. 2 shows a schematic configuration of a gas leakage measurement device previously proposed by the present inventor (Utility Application No. 1984-78463, Utility Model Application No. 02-656) One inner wall surface of the gas permeation cell 10 A semipermeable membrane 14 is placed on the side with a filter paper 12 interposed therebetween, and the peripheral portion of the semipermeable membrane 14 is pressed toward the filter paper 12 side by a ring-shaped gasket. This semi-permeable membrane 14 allows the gas permeable cell 1
0 is divided into a primary chamber 16 and a secondary chamber 18 (the filter paper 12 forms the secondary chamber). An inlet pipe 20 is connected to the primary chamber 16, and an outlet pipe 20 is connected to the secondary chamber 18.
2 are connected to each other, and the primary chamber 16 and the secondary chamber 18 can be communicated with each other through a communication pipe 26 via a solenoid valve 24. One end of the outlet pipe 22 is connected to a cylinder 30 of a gas leakage measuring device 28, and a solenoid valve 34 is further connected to this cylinder 30 via a diaphragm type differential pressure sensor 32, and a solenoid valve 34 is connected to the differential pressure sensor 32 via piping. Solenoid valves 36 are connected in parallel.

Before gas permeation measurement, the solenoid valves 24, 34, and 36 are opened, and the sample gas is introduced into the primary chamber 16 through the inlet pipe 20, and then into the secondary chamber 18 through the communication pipe 26. and then the outlet pipe 22
The liquid is introduced into the cylinder 30 through the electromagnetic valves 36 and 34 and then discharged to the outside. As a result, the entire flow path system is cleaned with the same sample gas, making it possible to measure the amount of gas permeation with high accuracy.

After this cleaning process, the electromagnetic valves 24, 34, and 36 are closed, and measurement of the amount of gas permeation is started. The sample gas at a set pressure higher than atmospheric pressure is introduced into the primary chamber 16 through the inlet pipe 20, and a portion of it is introduced into the semipermeable membrane 16.
4 and is led into the cylinder 30 through the outlet pipe 22. As a result, the gas pressure in the cylinder 30 becomes greater than the reference gas pressure in the flow path closed by the differential pressure sensor 32 and the solenoid valves 34 and 36, and the controller 38 operates the pulse motor 40 to 42 and drives the piston 44 downward in FIG.
Set the detected differential pressure to zero. A pulse generator 46 is connected to the rotating shaft of the pulse motor 40, and by counting the pulses supplied from the pulse generator 46, the controller 38 can detect the amount of gas permeation.

With this configuration, the reference gas pressure is always equal to the atmospheric pressure at the start of the measurement. Also, if the temperature changes after measurement starts, the reference gas pressure will also change.
Since the piston 44 is driven so that the differential pressure detected by the differential pressure sensor 32 becomes zero, the amount of gas in the cylinder 30 is proportional to the amount of movement of the piston 44, and the amount of gas permeation is automatically determined with temperature correction. Can be done.

This differential pressure sensor 32 has a well-known configuration that detects the differential pressure on both sides of a pressure-sensitive diaphragm using, for example, a strain gauge.

[Problem to be solved by the invention] However, a sealing material such as silicone resin is used on one side of the pressure-sensitive diaphragm of the differential pressure sensor 32, and since this sealing material adsorbs or releases gas, Even if the piston 44 is driven so that the differential pressure detected by the differential pressure sensor 32 becomes exactly zero, highly accurate measurement of the amount of gas permeation is hindered. Solenoid valve 34, 3
The same applies to the sealing material used in No. 6. The present invention was made based on the inventor's knowledge of these facts.

Generally, the gas permeability of the semipermeable membrane 14 is extremely low (for example, silicone rubber has a gas permeability of 4.70×10 ^-8 cm ³
cm/cm ² sec cmHg), this problem becomes more serious when the inner diameter of the cylinder 30 is made small, for example, from 4 to 16 mm, and high precision measurement is attempted in a short time.

In view of the above-mentioned problems, the purpose of the present invention is to measure the amount of gas permeation with high accuracy even when the amount of gas adsorption or the amount of gas released from the materials on both sides of the pressure-sensitive diaphragm of a differential pressure sensor is different. The purpose of the present invention is to provide a gas leakage measuring device that can measure gas leakage.

[Means for Solving the Problems] In order to achieve this object, the gas leakage measuring device according to the present invention is provided with a gas introduction path communicating with the inner chamber, and includes an inner volume variable means whose inner volume is variable. ,
a differential pressure sensor whose one side of the pressure-sensitive diaphragm is communicated with the inner chamber of the internal volume variable means through piping, and which detects the differential pressure on both sides of the pressure-sensitive diaphragm; and the other side of the pressure-sensitive diaphragm of the differential pressure sensor. a first valve that is connected to via piping and communicates/cuts off the other side with the outside; and a first valve that is interposed in piping that communicates both sides of the pressure-sensitive diaphragm of the differential pressure sensor, and that communicates/cuts off the other side with the outside.
A gas leakage amount measuring device comprising: a second valve that shuts off; and an internal volume control means that adjusts the internal volume of the internal volume variable means so that the differential pressure detected by the differential pressure sensor becomes a predetermined value. a container interposed in a pipe line closed by the first valve, the second valve, and the partition wall of the differential pressure sensor; and a pressure compensation substance sealed in the container and adsorbing or desorbing gas. ing.

[Example] An example of the present invention will be described based on FIG.

Note that the same components as in FIG. 2 are given the same reference numerals, and their explanations will be omitted.

The differential pressure sensor 32 is a well-known high-precision differential pressure sensor in which a pressure-sensitive diaphragm and a strain gauge are formed of silicon semiconductor. Different members are used on both sides of this pressure-sensitive diaphragm, and the seal member used on the cylinder 30 side adsorbs or desorbs gas as a whole depending on changes in temperature and pressure, gas adsorption density at that time, etc. shall be. Therefore,
A container 48 is interposed between the connection between the differential pressure sensor 32 and the electromagnetic valve 34, and a pressure compensating substance 50 having the same material and the same surface area as the sealing member is enclosed within the container 48.

Therefore, if the pressure compensating substance 50 adsorbs the reference gas in the container 48 as a whole with the solenoid valves 34 and 36 closed, the flow closed by the differential pressure sensor 32 and the solenoid valves 34 and 36 Although the reference gas pressure present in the passage decreases, the sealing member present on the cylinder 30 side of the pressure-sensitive diaphragm of the differential pressure sensor 32 also causes
Since the gas inside is adsorbed as a whole, the amount of gas permeation can be accurately measured by detecting the amount of movement of the piston 44.

The amount of pressure correction substance 50 is determined, for example, as follows. That is, by arranging a thin plate, such as a metal plate, which does not allow gas to pass through, in place of the semipermeable membrane 14, and opening the electromagnetic valves 24, 34, and 36, the sample gas is supplied from the inlet pipe 20 into the primary chamber 16. After cleaning the entire flow path system, the solenoid valves 24, 34, and 36 are closed, and the pulse motor 40 is operated so that the differential pressure detected by the differential pressure sensor 32 becomes zero. The amount of movement of the piston 44 per unit time at this time is measured while changing the amount of the pressure correction substance 50, and the appropriate amount of the pressure correction substance 50 is determined from the measured value.

(2) Expansion In the above embodiment, a case has been described in which the sealing member and the pressure correction substance 50 adsorb gas, but the same effect as described above can be obtained even when these remove gas.

Furthermore, the materials of the sealing member and the pressure correction substance 50 do not need to be the same, and it is sufficient as long as they correct the amount of gas adsorption or the amount of gas desorption on both sides of the differential pressure sensor 32 to be the same during measurement. .

Furthermore, this device can be applied to high-precision measurements such as the amount of oxygen gas permeated through contact lenses and the amount of gas leaking from various seals.

[Effects of the invention] As explained above, according to the gas leakage measurement device according to the invention, even when the amount of gas adsorbed or the amount of gas released from the substances on both sides of the pressure-sensitive diaphragm of a differential pressure sensor is different, This has the excellent effect of being able to measure the amount of gas permeation with high precision.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a gas leakage measuring device according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a conventional gas leakage measuring device. In the figure, 10 is a gas permeation cell, 12 is a filter paper, and 14
1 is a semipermeable membrane, 16 is a primary chamber, 18 is a secondary chamber, 20 is an inlet pipe, 22 is an outlet pipe, 24, 34, 36 are electromagnetic valves, 28 is a gas leakage measuring device, 30 is a cylinder, 32 is a Differential pressure sensor, 38 is controller, 4
0 is a pulse motor, 44 is a piston, 46 is a pulse generator, 48 is a container, and 50 is a pressure compensation substance.

Claims (1)

[Claims for Utility Model Registration] Inner volume variable means 30 and 44, each of which is provided with a gas introduction passage communicating with the inner chamber and whose inner volume is variable; a differential pressure sensor 32 communicating with the chamber and detecting the differential pressure on both sides of the pressure-sensitive diaphragm; and a differential pressure sensor 32 connected to the other side of the pressure-sensitive diaphragm of the differential pressure sensor via piping, and communicating the other side with the outside. /
A first valve 34 that shuts off the pressure sensitive diaphragm of the differential pressure sensor, a second valve 36 that is installed in a pipe that communicates with both sides of the pressure-sensitive diaphragm of the differential pressure sensor and that communicates/blocks both sides of the pressure sensitive diaphragm; An internal volume control means 38, 40, 42, 46 that adjusts the internal volume of the internal volume variable means to a predetermined value, in a gas leakage measuring device comprising: the first valve, the second valve, and A gas leak characterized in that a container 48 is installed in a conduit that is closed by the partition wall of the differential pressure sensor, and a pressure compensation substance 50 that is sealed in the container and adsorbs or desorbs gas. Quantity measuring device.