JP2001317658A - Leakage detection sensor of diaphragm valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leakage detection sensor of a diaphragm valve capable of detecting a leakage of a liquid securely even in case of the liquid having extremely poor electroconductivity like demineralized water. SOLUTION: In the diaphragm valve in which a diaphragm 14 is mounted at a position opposing to a valve seat 13 so as to shut off a surface side in contact with a liquid and a rear surface side and the diaphragm 14 comes into contact with and leaves the valve seat 13 by driving an operation shaft connected with a central part on the rear surface side to open and close a flow passage, a sensor main body 1 formed by sealing a strong electrolyte into a sealed casing 5 formed by arranging an osmotic film 4 which allows penetration of a liquid into the inside from the outside but does not allow its penetration to the outside partially and arranging cathode and anode electrodes a, b opposingly is provided in such a way that the osmotic film 4 is in contact with the liquid leaking out onto the rear surface side of the diaphragm 14. A detection circuit 2 detecting an electric conductivity condition between both electrodes a and b in the sealed easing 5 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak detection sensor for a diaphragm valve used for opening and closing the flow path of various liquid pipes in the food industry, the pharmaceutical industry, and the like.

[0002]

2. Description of the Related Art A diaphragm valve of this type is mounted at a position facing a valve seat in a valve body such that a diaphragm forming a valve body shuts off a front side and a rear side in contact with a liquid. The front side of the diaphragm is separated from and closes to the valve seat to open and close the flow path by the axially moving drive of the operating shaft connected to the central portion on the back side. Thus, in such a diaphragm valve,
As for the diaphragm, the front side and the back side having the operating mechanism are completely shut off at the fixed portion of the peripheral part, and the diaphragm always contacts the liquid only on the front side, and the valve operation is performed only by deformation of the diaphragm,
There is no sliding part that easily causes liquid leakage like the valve shaft part of other various valves, and the sealing performance in the valve part is high, so high reliability is required especially in safety and hygiene. It has been awarded in the food and pharmaceutical fields.

The diaphragm of a diaphragm valve used in an infusion production line, that is, a pure water line or the like,
In the case of damage due to fatigue or other factors, a function to detect the damage is necessary in order not to continue manufacturing a defective infusion. Conventionally, a method has been adopted in which the diaphragm is periodically replaced as early as possible before the diaphragm is damaged.However, in such an early replacement, the diaphragm that is still in a state that can sufficiently withstand long-term use will be discarded. It was uneconomic.

Further, as a conventional leak detection sensor attached to a diaphragm valve, there is known a sensor in which a conductive rubber layer is provided on a diaphragm to detect liquid leakage electrically. In a pure water line or the like, since pure water itself has extremely poor conductivity, accurate detection of liquid leakage cannot be performed, and the utility is poor.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a leak detection sensor for a diaphragm valve that can reliably detect a liquid leak even in the case of extremely poorly conductive liquid such as pure water. I have.

[0006]

According to a first aspect of the present invention, there is provided a leak detection sensor, wherein a diaphragm forming a valve element is provided at a position facing a valve seat in a valve body. A diaphragm valve that is mounted so as to shut off the rear side, and that opens and closes the flow path when the front side of the diaphragm 14 comes into contact with the valve seat 13 by the axial advance / retreat driving of an operating shaft 35 connected to the central part on the rear side. In the above, a strong electrolyte is sealed in a sealed casing 5 formed by partially arranging a permeable membrane 4 which allows a liquid to pass from the inside to the inside but does not pass from the inside to the outside, and a pair of electrodes a and b are opposed to each other. The sensor body 1 arranged is provided at a position where the permeable membrane 4 comes into contact with the liquid leaking to the back side of the diaphragm 14 and detects the conduction between the electrodes a and b in the closed casing 5. Inspection Characterized by comprising providing a circuit 2.

According to a second aspect of the present invention, there is provided a sensor for detecting a leakage of a diaphragm valve according to the first aspect.
However, it is characterized by comprising a thin main body film 14a made of fluororesin and a thick backup film 14b made of rubber disposed on the back side of the main body film 14a, and the backup film 14b is provided with a leak reporting hole 10.

[0008]

FIG. 1 is a front view of a diaphragm valve according to the present invention in a semi-longitudinal section, and FIG. 2 is a bottom view thereof. In these figures, reference numeral 11 denotes a tubular valve body, and a weir 23 forming a concavely curved valve seat 13 protrudes from a central portion of the valve body 11 in the longitudinal direction. Reference numeral 12 denotes a diaphragm mounting seat for mounting a surface side peripheral edge of a diaphragm 14 forming a valve body. The diaphragm mounting seat 12 is formed on a side wall 11a of the valve body 11, and inside the diaphragm mounting seat 12, a weir 2 is provided.
The valve ports 21a and 22a open to the inlet / outlet pipe portions 21 and 22 formed on both sides of the valve body 3 with the hole 3 interposed therebetween.

The diaphragm 14 is composed of a thin main body film 14a made of fluororesin and a thick backup film 14b made of rubber which is arranged on the back side of the main body film 14a. Are connected by a connection shaft 24 attached to the first shaft. As shown in FIG. 3, the main body film 14a is formed in a disk shape having a thickness of about 1 mm by Teflon (registered trademark) which is a fluororesin, and an annular convex portion 25 having a square cross section is formed on a peripheral portion of the surface. An annular ridge 19 is provided on the inner peripheral side of the annular ridge 25, and a linear ridge 20 connecting the annular ridge 19 in the diameter direction is provided. The thickness of the backup film 14b is 4
It is formed in a disk shape having a diameter of about mm and slightly larger in diameter than the main body film 14a. A metal retainer 26 is disposed on the back surface of the backup film 14b. The retainer 26, the backup film 14b, and the main film 14a are integrally connected via a connecting shaft 24 so as not to rotate with each other.

As shown in FIGS. 1 and 4, on the outer peripheral side of the diaphragm mounting seat 12, an annular pedestal 27 which is bolted to the bracket mounting flange 16 on the valve operating portion 15 side is provided from the seating surface of the diaphragm mounting seat 12. It is provided so as to protrude by a predetermined height. On the inner peripheral side of the diaphragm mounting seat 12, an upwardly protruding annular convex portion 28 is provided.
9 is formed. In this case, the bearing surface of the diaphragm mounting seat 12 substantially means the upper surface of the annular projection 28.

As shown in FIG. 4, an annular diaphragm pressing portion 30 is formed integrally with the bracket mounting flange 16 at its inner peripheral edge so as to protrude integrally with the flange 16, and the lower end pressing of the diaphragm pressing portion 30 is performed. Surface 30a
Is located at a position protruding downward by a predetermined length α from the contact surface 16 a of the bracket mounting flange 16 that contacts the annular pedestal 27. By forming the diaphragm pressing portion 30 in an annular body protruding downward from the contact surface 16a of the flange 16 in this manner, the peripheral edge of the diaphragm 14 can be effectively compressed. The projecting length α of the pressing portion 30 is such that the annular ridge 19 is sufficiently positioned on the annular convex portion 28 in a state where the peripheral portion of the diaphragm 14 having a predetermined thickness is fitted into the diaphragm mounting seat 12 as shown in the figure. It is set to a length that can press and compress the peripheral part so that it closely adheres,
In this setting, the projecting height of the diaphragm mounting seat 12 from the annular ridge portion 19 of the diaphragm mounting seat 12,
Consider the thickness of the diaphragm 14 and its elastic force.

As shown in FIG. 1, the valve operating section 15 is composed of an air cylinder connected to a bracket 18 having a flange 16 formed at a lower end thereof.
It is composed of a cylinder body 33, a piston (not shown), and a piston rod 35 that reciprocates in the axial direction integrally with the piston. The piston rod 35 forms an operating shaft of the diaphragm valve. The lower end of the piston rod (operating shaft) 15b is connected to a retainer 26, and the piston rod 35 is driven in the axial direction to drive the diaphragm 14 into contact with the valve seat 13 as shown by the solid line in FIG. As shown by the imaginary line in the figure, the form is changed to a valve-open form separated from the valve seat 13.

To attach the diaphragm 14 to the diaphragm mounting seat 12 of the valve body 11, first, the diaphragm 18 is attached to the diaphragm mounting seat 12 whose outer periphery is surrounded by the annular pedestal 27 with the bracket 18 removed from the valve body 11. 4, the annular projection 25 on the main body film 14a side is engaged with a concave step 29 formed on the outer periphery of the annular projection 28 on the mounting seat 12 side as shown in FIG. The portion 19 is brought into contact with the annular projection 28 of the mounting seat 12, and the linear ridge 20 is brought into contact with the valve seat 13. In this state, while the flange 16 of the bracket 18 is placed on the annular pedestal 27, the lower end of the diaphragm pressing portion 30 is pushed into and engaged with the annular groove 37 formed on the back side of the backup film 14b. Screw hole (not shown) to screw hole (not shown) of flange 16
Then, a bolt 17 (see FIG. 2) may be screwed in and tightened, and the flange 16 may be bolted to the annular pedestal 27. As a result, the diaphragm holding portion 30 is
Of the main membrane 1 is compressed uniformly over its entire circumference.
The annular ridge 19 of 4a is pressed against the annular projection 29 of the diaphragm mounting seat 12, and the space between the main body film 14a and the annular projection 29 of the mounting seat 12 can be completely sealed.

Next, a description will be given of a leak detection sensor provided in the diaphragm valve constructed as described above. The leak detection sensor is provided with an opening provided in a required portion of the bracket 18 as shown in FIGS. The sensor main body 1 is inserted into the sensor main body 31 and a detection circuit 2 is provided to be drawn out of the sensor main body 1 to the outside of the bracket 18. Further, a leak reporting hole 10 is provided in the backup film 14b of the diaphragm 14.

As shown in FIG. 4, the sensor main body 1 is a closed casing comprising a box-shaped casing main body 3 having one side open and a permeable membrane 4 disposed on the opening side of the casing main body 3. 5, a strong electrolyte is sealed therein, and a pair of anode and cathode electrodes a and b are arranged to face each other. The permeable membrane 4 allows the liquid to pass from the outside of the closed casing 5 to the inside thereof, but is provided on the opening side of the casing main body 3 so as to prevent the liquid entering the inside of the casing 5 from leaking outside. It is.

As the strong electrolyte sealed in the closed casing 5 of the sensor body 1, NaCl (sodium chloride used as salt or the like) is used.
OH (caustic soda, sodium hydroxide) and the like can also be used. As shown in FIG. 4, the detection circuit 2 is an electric circuit formed by electrodes a and b disposed in a closed casing 5, a power supply 6 composed of a battery, an ammeter 7, and a lamp 8. .

When attaching the sensor body 1 to the opening 31 of the bracket 18, the osmosis membrane 4 is located inside the bracket 18, that is, the osmosis membrane 4 comes into contact with the liquid leaking to the back side of the diaphragm 14. In such a state, the casing body 3 is attached and fixed to the opening 31 via the sealing material 9.

In the leak detection sensor configured as described above, if the diaphragm valve is installed in a pure water line and the main membrane 14a of the diaphragm 14 is damaged, the surface of the main membrane 14a is damaged. Water (pure water) leaking from the damaged portion to the back side thereof is removed from the main body film 14a.
It penetrates into the gap between the back surface and the front surface of the backup film 14b, passes through the leak reporting hole 10 of the backup film 14b, and flows into the inside of the bracket 18, ie, the space S on the back surface side of the diaphragm 14, and accumulates. The leaked water accumulated in the space S passes through the permeable membrane 4 provided in the closed casing 5 of the sensor main body 1 and passes through the Na inside the closed casing 5.
Mix with Cl. When the leaked water is mixed with NaCl, the dielectric constant of the water is large, so that NaCl is dissociated into Na ions (+) and Cl ions (-), that is, it is ionized. Moreover, since NaCl is a strong electrolyte, it completely dissociates in water (there is no molecule that does not ionize).

As described above, when NaCl is ionized in the leaked water that has entered the inside of the closed casing 5 of the sensor body 1, the conductivity of the water increases, and the two electrodes a and b in the casing 5 are in a conductive state. Becomes The conduction state of the two electrodes a and b is detected by the lighting of the lamp 8, and the degree of conduction is confirmed by the display of the ammeter 7. Therefore, it is determined that the main body film 14a of the diaphragm 14 is damaged.
It can be known by this leak detection sensor.

According to this leak detection sensor, even in the case of a very poorly conductive liquid such as pure water, the main body film 14a
Leakage from the vehicle can be reliably detected. Further, the diaphragm 14 includes a thin main body film 14a made of fluororesin,
A thick backup film 14b made of rubber and arranged on the back side of the backing film 14b.
b, the main body film 14 is provided.
The water leaking out from the damaged portion of a is immediately passed through the leak notification hole 10 to the rear side of the diaphragm 14 and comes into contact with the sensor main body 1, so that the main body membrane 14a is damaged. You can know quickly.

In this embodiment, detection of leakage of pure water at the diaphragm 14 in the pure water line has been described. However, this leakage detection sensor is not limited to pure water, and can also detect leakage of liquids other than pure water. You can do it.

[0022]

According to the leak detecting sensor of the first aspect of the present invention, when the diaphragm is damaged, the liquid leaking to the back side of the diaphragm is mixed with the strong electrolyte inside the casing through the permeable membrane of the sensor body. By doing so, the strong electrolyte is ionized and the conductivity of the liquid increases, so that by detecting the conduction state between the two electrodes in the casing, it is possible to know the breakage of the diaphragm, and thus to determine the life of the diaphragm. Can be used as long as possible. In particular, according to this leak detection sensor, even in the case of a very poorly conductive liquid such as pure water, it is possible to reliably detect the leakage of the liquid due to the breakage of the main body film.

According to a second aspect of the present invention, the diaphragm is composed of a thin main body film made of a fluororesin and a thick backup film made of a rubber which is arranged on the back side of the main body. By providing the holes, it is possible to quickly know that the main membrane is damaged.

[Brief description of the drawings]

FIG. 1 is a half sectional front view of a diaphragm valve provided with a leak detection sensor according to the present invention.

FIG. 2 is a bottom view of the diaphragm valve shown in FIG.

3A is a front view of a diaphragm, and FIG. 3B is a cross-sectional view taken along line XX of FIG. 3A.

FIG. 4 is a partially enlarged cross-sectional view of the diaphragm valve shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor main body 2 Detection circuit 3 Casing main body 4 Permeation membrane 5 Hermetic casing 10 Leakage reporting hole 11 Valve body 13 Valve seat 14 Diaphragm 15 Valve operation part a, b Electrode

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[Procedure amendment]

[Submission Date] May 12, 2000 (2000.5.1)
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

As shown in FIG. 1, the valve operating section 15 is composed of an air cylinder connected to a bracket 18 having a flange 16 formed at a lower end thereof.
It is composed of a cylinder body 33, a piston (not shown), and a piston rod 35 that reciprocates in the axial direction integrally with the piston. The piston rod 35 forms an operating shaft of the diaphragm valve. The lower end of this piston rod (operating shaft) 35 is connected to the retainer 26, and the diaphragm 1
4 changes its form into a valve-closed form in contact with the valve seat 13 as shown by the solid line in FIG. 1 and a valve-opened form separated from the valve seat 13 as shown by the phantom line in FIG.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

To attach the diaphragm 14 to the diaphragm mounting seat 12 of the valve body 11, first, the diaphragm 18 is attached to the diaphragm mounting seat 12 whose outer periphery is surrounded by the annular pedestal 27 with the bracket 18 removed from the valve body 11. 4, the annular projection 25 on the main body film 14a side is engaged with a concave step 29 formed on the outer periphery of the annular projection 28 on the mounting seat 12 side as shown in FIG. The portion 19 is brought into contact with the annular projection 28 of the mounting seat 12, and the linear ridge 20 is brought into contact with the valve seat 13. In this state, while the flange 16 of the bracket 18 is placed on the annular pedestal 27, the lower end of the diaphragm pressing portion 30 is pushed into and engaged with the annular groove 37 formed on the back side of the backup film 14b. Screw hole (not shown) to screw hole (not shown) of flange 16
Then, a bolt 17 (see FIG. 2) may be screwed in and tightened, and the flange 16 may be bolted to the annular pedestal 27. As a result, the diaphragm holding portion 30 is
Of the main membrane 1 is compressed uniformly over its entire circumference.
The annular ridge 19 of 4a is pressed against the annular projection 28 of the diaphragm mounting seat 12, and the space between the main body film 14a and the annular projection 28 of the mounting seat 12 can be completely sealed.

Continuation of the front page (72) Inventor Toru Tateishi 1170-9, Matsuoyu, Sokabe, Tsuyama-shi, Okayama Prefecture F-term in Toyo Stainless Steel Corporation (reference) 2G067 AA37 BB11 CC01 DD22 DD23 3H065 AA08 BB14 BB24 BC09

Claims (2)

[Claims] 1. A diaphragm forming a valve body is mounted at a position facing a valve seat in a valve body so as to shut off a front side and a rear side in contact with a liquid, and is connected to a central part on the rear side. In the diaphragm valve, the front side of the diaphragm moves away from and closes the valve seat to open and close the flow path by the axial movement of the operating shaft, and a part of the permeable membrane that allows liquid to pass from inside to outside but does not pass from inside to outside. A sensor body in which a strong electrolyte is sealed in a closed casing formed by disposing a pair of electrodes and opposed to each other is provided at a position where the permeable membrane comes into contact with the liquid leaking to the back side of the diaphragm. A leakage detection sensor for a diaphragm valve, further comprising a detection circuit for detecting a conduction state between both electrodes in the closed casing. 2. The diaphragm according to claim 1, wherein the diaphragm comprises a thin main body film made of fluororesin and a thick backup film made of rubber which is arranged on the back side of the main film, and a leak reporting hole is provided in the backup film. Diaphragm leak detection sensor.