JPH05274043A - Calibrating method for gas governor opening degree detector and gas governor abnormality monitor device - Google Patents

Abstract

PURPOSE:To easily detect the degree of opening of a gas governor to perform calibration by adjusting the length of a detecting rod, which has one end part fixed to a reflecting member and has the other end abutting on a driving piece, to adjust the quantity of the light received from the reflecting member of radiating light. CONSTITUTION:A Reynold gas governor 2 is provided in an airtight governor chamber 1 having an explosion proof structure. For the purpose of detecting the degree of opening of the gas governor 2, first and second optical fibers 3 and 4 are airtightly provided from the inside to the outside of the governor chamber 1, and an electric circuit 5 is provided on the outside of the governor chamber 1. The light from a light emitting diode 56 of the electric circuit 5 is led through the fiber 3, and the light from an end part 57 is projected to a reflecting member 59 of an opening degree detecting mechanism 58. The reflected light is led to the electric circuit 5 from an end part 60 of the fiber 4 and is detected by a photo transistor 61. An abutting member 90 can be vertically displaced to adjust the length of a detecting rod 65 in the axial direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a calibration method for an opening degree detecting device for detecting the opening degree of a gas governor for keeping a secondary pressure of city gas or the like constant, and also monitoring abnormality of the gas governor. For equipment.

[0002]

2. Description of the Related Art In order to detect the opening of a gas governor, conventionally, a differential transformer is directly connected to a spindle fixed to a discriminator of the gas governor.
When a plurality of opening degree detection devices are provided, their outputs are transmitted to monitor the gas governor at a remote place.

[0003]

In such a prior art, the level of the output from the opening detection device provided individually for each of the plurality of gas governors must correspond exactly to the opening of the gas governor. Otherwise, the output level from the differential transformer provided in each opening detection device and the opening of the gas governor must be corrected on the receiving side, which makes it difficult to monitor the abnormality of the gas governor. Becomes

An object of the present invention is to make it possible to easily calibrate a device for detecting the opening degree of a gas governor, and thus to easily monitor abnormality of a plurality of gas governors. A calibration method for a detection device and an abnormality monitoring device for a gas governor.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a drive piece attached to a spindle fixed to a valve body of a gas governor, a reflecting member, one end portion fixed to the reflecting member and the other end portion to the driving piece. A detection rod that is in contact with the reflecting member, the length of which is adjustable, a light source unit that irradiates the reflecting member with light, a light receiving unit that receives light from the reflecting member, and a gain adjusting unit that adjusts the gain of the light receiving unit. In a calibration method for a gas governor opening detection device comprising, in the closed state of the gas governor, the one end of the detection rod is set to a predetermined position, between the driving piece and the other end of the detection rod, in advance, The step of adjusting the length of the detection rod through a jig having a predetermined thickness, and the step of adjusting the gain so that the output of the light receiving means has a predetermined value after the jig is removed with the gas governor closed. The steps of operating the adjustment means It is a calibration method for opening detecting apparatus gas governor according to claim Mukoto.

Further, the present invention is provided with a plurality of opening detecting devices, each opening detecting device being mounted on a spindle fixed to the valve body of the gas governor, a reflecting member, and a reflecting member.
One end is fixed to the reflecting member, the other end is in contact with the driving piece, the length of which can be adjusted, the detection rod, the light source means for irradiating the reflecting member with light, and the light from the reflecting member is received. The opening detection device includes a light receiving unit and a gain adjusting unit that adjusts the gain of the light receiving unit, and each opening detection device determines the output characteristic of the light receiving unit corresponding to the opening of the gas governor by the length of the detection rod and the gain adjusting unit. An abnormality monitoring device for a gas governor, which includes means for receiving an output from the light receiving means of each opening detection device, discriminating the level of each output and monitoring an abnormality of the gas governor. is there.

[0007]

According to the present invention, the spindle is fixed to the valve body of the gas governor, the drive piece is attached to this spindle, one end of the detection rod is fixed to the reflection member, and the other end of the detection rod is fixed. The portion is in contact with the driving piece, the length of the detection rod is adjustable, light is emitted from the light source means to the reflecting member,
The reflected light is received by the light receiving means, and thus an output from the light receiving means having a level corresponding to the displacement position of the reflecting member and thus the opening degree of the valve body of the gas governor is obtained, and the output level of the light receiving means is variable, for example. The gain can be adjusted by a gain adjusting means realized by a resistor or the like, and in order to perform calibration, the gas governor is in a closed state, that is, the valve body is in a position where it is seated on the valve seat, and in this state, The one end to which the reflecting member is fixed is set to a predetermined position, and, for example, the reflecting member is brought into contact with the ends of the light source means and the light receiving means, and the other end of the driving rod and the detecting rod is set. A jig having a predetermined thickness is interposed between the two so that the other end of the detection rod contacts the jig on the driving piece, the length of the detection rod is adjusted, and then the jig is removed. In a state in which gas governor is closed,
The gain adjusting means is operated to adjust the gain of the light receiving means so that the output of the light receiving means becomes a predetermined value. In this way, in the opening degree detecting device individually provided for each of the plurality of gas governors, it is possible to calibrate all the opening degree detecting devices so that the output level of the light receiving means corresponding to the opening degree of the gas governor can be obtained. It will be possible. Therefore, the output of the light receiving means of each of the plurality of opening detection devices represents the opening of the gas governor calibrated over all the opening detection devices,
Therefore, it becomes possible to easily monitor the abnormality by discriminating the output level of the light receiving means.

[0008]

1 is a simplified diagram of an embodiment of the present invention. In the airtight governor chamber 1 with explosion-proof structure,
As shown in FIG. 2, a Reynold's gas governor 2 is provided. In order to detect the opening degree of the Reynold type gas governor 2, a first optical fiber 3 and a second optical fiber 4 are provided in an airtight manner from the inside of the governor chamber 1 to the outside, and an electric circuit is provided outside the governor chamber 1. 5 are provided. Light from a light emitting diode 56, which is a light emitting element in the electric circuit 5, is guided through the first optical fiber 3, and light from the end portion 57 of the first optical fiber 3 is a reflection member of the opening degree detection mechanism 58. The light emitted to 59 and reflected in this way is guided from the end 60 of the second optical fiber 4 by the second optical fiber 4 and detected by the phototransistor 61 which is a light receiving element provided in the electric circuit 5. .. The optical fiber 3 and the light emitting diode 56 constitute a light source means. The optical fiber 4 and the phototransistor 61 form a light receiving means.

A specific structure of the opening detection mechanism 58 will be described. The casing 62 made of a light-shielding material, such as metal, is in the shape of a right cylinder having a ceiling plate 63, and the flat reflecting member 59 has a horizontal reflecting surface above the
It can be displaced up and down. A guide member 64 is screwed into the lower portion of the casing 62, and a detection rod 65 is attached to the guide hole 85 of the guide member 64 screwed into the casing 62 so as to be vertically displaceable. The hole 85 guides the detection rod 65 in the axial direction. Detection rod 6
5 has a detection rod main body 86, one end of the detection rod main body 86 is screwed and fixed to the reflection member 59, and the other end thereof is screwed and fixed to the mounting member 87. A coil spring 67 is interposed between the spring receiving portion 88 protruding outward in the radial direction at the lower end of the mounting member 87 and the bottom of the spring hole 89 of the guide member 64, whereby the detection rod 65 moves downward in FIG. Spring force is applied. The contact member 90 that constitutes the detection rod 65 is
It has a contact portion 91 that contacts the drive piece 73, and a shaft portion 92 that is integrally formed with the contact portion 91 and that has an external thread. The threaded portion 92 is screwed into the inner thread of the mounting member 87, so that the contact member 90 can be displaced up and down, and thus the axial length of the detection rod 65 can be adjusted. The lock nut 93 is screwed onto the shaft portion 92. On the ceiling plate 63, the ends 57, 60 of the first and second optical fibers 3, 4 are attached.
Is attached to the detecting rod 65 near the axis of the detecting rod 65.
Immediately above, the end 57 faces the reflecting member 59, and the end 60 also faces the reflecting member 59. Thus, the light from the end portion 57 of the first optical fiber 3 strikes the reflecting surface of the reflecting member 59 almost perpendicularly and is reflected, and the reflected light from the reflecting member 59 is:
As described above, the light is received and guided by the end portion 60 of the second optical fiber 4. When the detection rod 65 is pushed upward in FIG. 1, the ends 5 of the first and second optical fibers 3 and 4 are
The distance L between the lower end of 7, 60 and the reflective surface of the reflective member 59 changes. This distance L and the phototransistor 61
And the electric signal level obtained from the above have the relationship shown in FIG. The light intensity generated from the light emitting diode 56 is always a constant value, and as the distance L increases,
The electric signal level obtained from the phototransistor 61 decreases. The detection operation is performed in the range L0 in FIG. The output of the phototransistor 61 is amplified by the amplifier circuit 81, and the distance L corresponding to the output level of the phototransistor 61, and thus the displacement of the valve body 10, is transmitted via the transmission circuit 82 and the transmission line 98. In this Figure 3,
By operating the variable resistor 97 which is the gain adjusting means provided in the amplifier circuit 81 of FIG. 1, the gain of the amplifier circuit 81 is changed and adjusted, and the characteristic line 94 serving as a reference is obtained. When the gain of the amplifier circuit 81 is increased, the characteristic of the line 96 is obtained, and when the gain is decreased, the gain shown by the line 95 is obtained. The line 94 is a reference characteristic that should be obtained from the amplifier circuit 81 in a state according to the opening degree of the governor 2. At this time, if the governor 2 is closed, the ends of the first and second optical fibers 3 and 4 are closed. Distance L between the parts 57 and 60 and the reflecting surface of the reflecting member 59
Is a value L1, and when the amplifier circuit 81 has the characteristic of the line 94, the level of the output voltage obtained from the amplifier circuit 81 is V1. The opening degree detection mechanism 58 and the electric circuit 5 constitute an opening degree detection device 99. Such an opening degree detection device is individually provided for each of the plurality of gas governors 2.

Referring to FIG. 4, the opening degree detecting devices are indicated by reference numerals 99a to 99c, respectively.
The subscripts a, b and c are omitted. An electric signal from the opening degree detection device 99 is transmitted from the transmission line 98, for example, a public telephone line, to the abnormality monitoring means 101 via the exchange 100 and received. The abnormality monitoring means 101 is realized by, for example, a personal computer or the like, and individually performs level discrimination of the electric signal representing the opening degree of each gas governor transmitted from the plurality of opening degree detecting devices 99a, 99b, 99c, Range of normal gas governor opening V1
When V2 (see FIG. 3) is deviated, a display indicating the abnormal state is displayed and an alarm is issued. In this manner, in the abnormality monitoring means 101, in order to be able to discriminate the level of the signal indicating the opening degree from each of the opening degree detecting devices 99a, 99b, 99c at a predetermined constant level, in order to discriminate a plurality of signals, By the length of the detection rod 65 in the opening detection device 99 and the variable resistor 97 as the adjusting means, each line 94, 95, 96 of FIG. 3 obtained from the amplifier circuit 81 corresponding to the opening of each gas governor 2. Among them, it must be configured so as to match the characteristics of the predetermined line 94. The present invention provides this calibration method as will be described later and also provides an abnormality monitoring apparatus for the same.

FIG. 5 is a side view showing a state in which the opening detection mechanism 58 is fixed on the main valve 8 of the Reynold type gas governor 2. One end of a mounting member 68 is fixed to the casing 62. The other end of the mounting member 68 is bent and screwed onto the upper portion of the main valve 8 using a bolt 70. A pin 7 is attached to the spindle 11 via a mounting piece 71.
A lever 22 is attached by means of 2 so as to be angularly displaceable, and a drive piece 73 capable of contacting the lower end portion of the detection rod 65 is fixed to this spindle 11. When the spindle 11 is displaced up and down, its drive piece 73
The contact piece 91 of the detection rod 65, which is pressed upward by the spring 73, is displaced, the reflecting member 59 is moved up and down accordingly, and the distance L is changed. As a result, the spindle 11 and thus the valve body 10 of the main valve 8 of the gas governor 2 described later
The opening degree of can be detected.

A procedure for calibrating the opening degree detection device 99 will be described with reference to FIGS. For calibration, first, the auxiliary valve 103 shown in FIG. 9 is closed, whereby the valve body 10 of the main valve 8 of the gas governor 2 is seated on the valve seat and the gas governor 2 is closed. This brings the spindle 11, and thus the drive piece 73, to the predetermined upper limit position. Next, as shown in FIG. 6, the lock nut 93 is rotated around the shaft portion 92 of the contact member 90 to loosen the lock nut 93 from the mounting member 87. Next, the detection rod 65 is raised and the reflection member 59
Are the ends 57, 60 of the first and second optical fibers 3, 4.
To be in contact with. In this way, the one end of the detection rod 65, and thus the reflecting member 59, is set to a predetermined upper limit position.

Then, the contact member 90 is rotated so that the shaft portion 92 thereof is inserted into the mounting member 87, and thus the contact member 90 is raised to the state shown in FIG.

In the state of FIG. 7, the drive piece 73 and the detection rod 6 are
A jig 104 having a predetermined thickness d1 is interposed between the contact member 90 and the contact piece 91.

After that, the contact member 90 of the detection rod 65 is rotated and displaced downward in FIG.
To be in contact with the surface of. In this state, the lock nut 93 is tightened to fix the contact member 90 and the mounting member 87. After that, the jig 104 is attached to the drive piece 73 and the contact piece 91.
Remove from between. Therefore, the contact piece 91 has the spring 6
The spring force of 7 causes the drive piece 73 to come into contact with it as shown in FIG. At this time, the auxiliary valve 103
Remains closed, and thus the gas governor 2 is kept closed. In this way, the ends 57 and 60 of the first and second optical fibers 3 and 4 and the reflecting member 59.
The distance L between the reflective surface and the reflective surface will be set to the reference distance L1 described with reference to FIG. The reference distance L1 is, for example, 5 mm, and the thickness d of the jig 104 is
Is equal to 1.

Next, as shown in FIG. 1, the amplifier circuit 8
The voltmeter 105 for measuring the output voltage of 1 is connected, the variable resistor 97 is operated, and the voltage measured by the voltmeter 105 is set to be V1 in FIG. Thus, a series of work is completed. In this way, the opening degree detection device 99 obtains the characteristics shown by the line 94 in FIG.
This calibration work is performed for all the opening degree detecting devices 99a, 99b, 99c individually provided for each gas governor 2, and thus the characteristics of the output of the light receiving means corresponding to the opening degree of the gas governor 2 are made uniform. Calibration can be done.

The overall structure of the gas governor 2 will be described below.

Gas such as city gas is supplied from the primary side pipe line 6 in FIG. 9 through the filter 7, passes through the main valve 8 as a main unit, and the secondary side pipe line 9 to a certain amount. A gas having a secondary pressure is supplied. This Reynolds type gas governor is a gas governor for reducing the pressure from a so-called medium and low pressure of, for example, less than 3 kg / cm ² to a low pressure, and is used for a district pressure regulator. The main valve 8 has two valve bodies 10, and the valve body 10 has a diaphragm spindle 1
1 and is connected to the main diaphragm 12. Secondary pressure is introduced into the chamber 13 below the diaphragm 12. The secondary pressure control mechanism is connected via the medium pressure auxiliary governor 15 connected to the primary pressure adjusting pipe 14, the low pressure auxiliary governor 17 connected via the adjusting pipe 16, and the pipe line 18. It has an auxiliary ball 19 which is a supporting ball. The low-pressure auxiliary governor 17 is connected to the conduit 9 via the secondary pressure adjusting pipe 20. An auxiliary valve 103 that can close the main valve 8 for calibration is interposed in the secondary pressure adjusting pipe 20. A needle valve 21 is interposed in the adjusting pipe 16. In order to connect the main valve 8 and the auxiliary ball 19, the lever 22 and the hanging rod 23
Is provided, a lever 22 and a suspension rod 23 are provided, and an auxiliary weight 24 for opening the main valve 8 and a main weight 25 are mounted on the lever 22 and the suspension rod 23.

The secondary pressure control of this governor is performed as follows. When there is no demand on the secondary side, the secondary pressure is high, at this time the low-pressure auxiliary governor 17 remains closed, and the intermediate-pressure auxiliary governor 15 is 450-500.
Since the pressure is set to an intermediate pressure of mmH ₂ O, this pressure is applied to the chamber 27 below the diaphragm 26 of the auxiliary ball 19 via the adjusting pipe 16 and thereby pushes the suspension rod 23 and the lever 22. By raising, the two valve bodies 10 of the main valve 8 are raised and completely closed. Closing the auxiliary valve 103 described above at the time of calibration is equivalent to keeping the low-pressure auxiliary governor 17 in the closed state. Therefore, at the time of calibration, the main valve 8 is closed as described above.

When a demand is generated on the secondary side and the secondary pressure drops, the low pressure auxiliary governor 17 operates and the auxiliary ball 1
The gas in the room 27 of 9 begins to flow to the secondary side. At this time,
The intermediate pressure auxiliary governor 15 also starts to work, but there is a throttle by the needle valve 21 between the auxiliary ball 19 and
Since the flow rate is limited, the intermediate pressure in the adjusting pipe 16 is lowered, the diaphragm 26 of the auxiliary ball 19 is lowered, the suspension rod 23 and the lever 22 are lowered, and the main valve 8 is opened.

When the demand decreases and the secondary pressure rises, the low pressure auxiliary governor 17 closes, the intermediate pressure rises, and the main valve 8 closes. The setting of the secondary pressure can be adjusted by the number of small weights placed on the low pressure auxiliary governor 17.

FIG. 10 is a simplified sectional view of the main valve 8. The diaphragm spindle 11 is also called a center stem, and the valve body 10 is fixed here. The valve body 10 is provided with a guide piece 10a, which is guided to the valve hole, whereby the lateral runout of the spindle 11 is prevented.

FIG. 11 is a simplified sectional view showing the structure of the intermediate pressure auxiliary guide 15. This medium pressure auxiliary governor 15
It is a kind of direct-acting type governor, and the role of the intermediate pressure auxiliary governor 15 is to detect the pressure in the adjusting pipe 16 and supply the gas in the adjusting pipe 14 on the primary side of the governor into the adjusting pipe 16. Is. The set pressure of the intermediate pressure auxiliary governor 15 is usually 450.
˜500 mmH ₂ O, and the adjustment of the set pressure is performed by the tightening degree of the spring 29. The diaphragm 31 provided with the weight 30 is urged downward by the spring 29, so that the lever 32 urges the valve body 33 upward in FIG. 11. The valve element 33 can be seated on the valve seat 34.

FIG. 12 is a sectional view of the low pressure auxiliary governor 17. This low-pressure auxiliary governor 17 is one type of direct-acting type governor, like the above-mentioned intermediate-pressure auxiliary governor 15, and its role is to detect the pressure on the secondary side of the governor and to operate the valve of the spindle 35 which is a valve element. The main valve 8 is opened and closed by opening and closing the seat 36 and varying the intermediate pressure in the adjusting pipe 16. The set pressure is adjusted by increasing or decreasing the number of weights 38 placed on the diaphragm 37. A lever 39 is connected to the diaphragm 37,
The lever 39 urges the weight 38 in the direction away from the spindle 35 and the valve seat 36 by gravity.

FIG. 13 is a sectional view of the needle valve 21 interposed in the adjusting pipe 16. The needle valve 21 sets the needle-shaped valve body 40 by adjusting the valve seat 41 so as to be adjustable. The needle valve 21 plays a role when the intermediate pressure is slightly reduced by the operation of the low pressure auxiliary governor 17. That is, the fluctuation effect is prevented from being canceled by the action of the intermediate pressure auxiliary governor 15, and the main valve 8 works smoothly. Therefore, the needle valve 21 gives a time lag to the recovery of the intermediate pressure in the adjusting pipe 16 by reducing the flow rate of the gas adjusted by the intermediate pressure auxiliary governor 15.

FIG. 14 is a sectional view of the auxiliary ball 19. This auxiliary ball 19 guides the gas adjusted by the intermediate pressure auxiliary governor 15 to the lower chamber 27 of the diaphragm 26, and the diaphragm 26 is displaced up and down by the pressure fluctuation, and the main body is moved through the suspension rod 23 and the lever 22. The diaphragm spindle 11 of the valve 8 is moved up and down to open and close the main valve 8. The auxiliary weight 24 and the main weight 25 are attached to the lever 22 and the suspension rod 23 as described above.

The chamber 13 below the main diaphragm 12 of the main valve 8 is connected from the relief pipe 42 to the secondary conduit 9 via the relief pipe valve 43.

[0028]

As described above, according to the present invention, the spindle is fixed to the valve body of the gas governor, the drive piece is attached to the spindle, and one end of the detection rod whose length can be adjusted. Is fixed to the reflecting member, the other end is in contact with the driving piece, the reflecting member is irradiated with light from the light source means, the reflected light is received by the light receiving means, and the gain of the light receiving means is adjusted by the gain adjusting means. At the time of calibration, with the gas governor closed, one end of the detection rod, which is fixed to the reflective member, is set to a predetermined position, and in this state, the gap between the drive piece and the other end of the detection rod is set. After adjusting the length of the detection rod through the jig, and then removing the jig, adjust the gain of the light receiving means by operating the gain adjusting means with the gas governor still closed. Provided for each gas governor The characteristics of the output of the light receiving means in the opening detection device are made uniform, the output from each light receiving means is received by the abnormality monitoring means, the level of each output is discriminated, and thus it is easy to remotely monitor the abnormality of the gas governor. This makes it possible to prevent erroneous detection of abnormalities.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 2 is a diagram showing a simplified overall configuration of an embodiment of the present invention.

FIG. 3 is a graph showing characteristics of an opening degree detection device 99.

FIG. 4 is an overall block diagram showing an apparatus for detecting an abnormality in each gas governor 2 by using opening degree detection apparatuses 99a, 99b, 99c provided for each of the plurality of gas governors 2.

FIG. 5 is a side view showing a state in which an opening degree detection mechanism 58 is attached to the main valve 8 of the gas governor 2.

FIG. 6 is a cross-sectional view showing a state in which one end of the detection rod 65 is set to a predetermined position with the gas governor 2 closed.

7 is a cross-sectional view showing a state in which a jig 104 is interposed between a driving piece 73 and a detection member 90 of a detection rod 65. FIG.

FIG. 8 is a cross-sectional view showing a state in which a contact piece 91, which is the other end of the detection rod 65, is in contact with the jig 104 on the drive piece 73 while the gas governor 2 is closed.

FIG. 9 is a diagram showing a configuration of a Reynold's gas governor 2.

FIG. 10 is a cross-sectional view showing a configuration of a main valve 8.

FIG. 11 is a cross-sectional view showing a configuration of an intermediate pressure auxiliary governor 15. .

FIG. 12 is a diagram showing a configuration of a low pressure auxiliary governor 17.

FIG. 13 is a cross-sectional view showing the structure of a needle valve 21.

FIG. 14 is a cross-sectional view showing a configuration of an auxiliary ball 19.

[Explanation of symbols]

 1 Governor chamber 2 Gas governor 3 First optical fiber 4 Second optical fiber 5 Electric circuit 8 Main valve 10 Valve body 11 Spindle 56 Light emitting diode 58 Opening detection mechanism 59 Reflecting member 61 Phototransistor 65 Detection rod 67 Spring 73 Driving piece 81 Amplification Circuit 86 Detection rod main body 87 Mounting member 90 Abutting member 97 Gain adjusting means 98 Transmission line 100 Exchanger 101 Abnormality monitoring means

Claims (2)

[Claims] 1. A drive piece attached to a spindle fixed to a valve body of a gas governor, a reflecting member, one end fixed to the reflecting member, and the other end abutting the driving piece, the length of which is adjusted. An opening detection device for a gas governor, which includes a detection rod that is possible, a light source unit that irradiates the reflecting member with light, a light receiving unit that receives the light from the reflecting member, and a gain adjusting unit that adjusts the gain of the light receiving unit. In this calibration method, the one end of the detection rod is set to a predetermined position with the gas governor closed, and a jig having a predetermined thickness is interposed between the driving piece and the other end of the detection rod. And adjusting the length of the detection rod, and with the gas governor closed, after removing the jig, operating the gain adjusting means so that the output of the light receiving means becomes a predetermined value. Characterized by including Calibration method for opening detecting apparatus Sugabana. 2. A plurality of opening detection devices are provided, each opening detection device being mounted on a spindle fixed to a valve body of a gas governor, a reflecting member, and one end fixed to the reflecting member. The other end is in contact with the driving piece, and the length of the rod is adjustable, the light source means for irradiating the reflecting member with light, the light receiving means for receiving light from the reflecting member, and the light receiving means of the light receiving means. Each opening degree detection device is provided with gain adjusting means for adjusting the gain, and the characteristics of the output of the light receiving means corresponding to the opening degree of the gas governor are made uniform by the length of the detection rod and the gain adjusting means. An abnormality monitoring device for a gas governor, comprising means for receiving an output from a light receiving means of the degree detecting device, discriminating a level of each output and monitoring an abnormality of the gas governor.